Rubbish Mechanical Extractors

This is what an extractor fan louvre should look like when in operation. I am not sure that I have ever seen this in practice. Wracked my brains, but apart from louvres on commercial systems I cannot recollect ever seeing much more than an occasional feeble movement. Certainly on my home there is rarely more than a flutter.

So if the louvres aren't moving, then the fan is not working properly, but this is the situation with virtually all extractors in the UK. So this in turn means that we are not dealing with ventilation as we should. All the calculations in Part F of the building regs etc are just a waste of time if the equipment we use is just rubbish.

The real life situation is made worse of course if the vents are facing the prevailing winds. With such minor pressure coming from the fans any extracting doesn't stand a chance against any sort of wind. Then we also fit any draught devices that just make it even more difficult for a poor fan to extract the volume of air required to keep condensation down to acceptable levels.

So what to do?

Well, it is worth having a look at a video from Envirovent. https://youtu.be/k5rlDfWPAgw. This helps to show the effectiveness of different types of fan on the market.

This video looks at standard type fans, but you could also look at a dMEV fans. dMEV are Decentralised Mechanical Extract Vents. These work by continuously extracting air from a localised position (like in a bathroom). There are various manufacturers and types. So you can have more sophisticated ones that work by sensing factors like humidity, so as humidity increases, so the fan will respond according by extracting more air. They can also be controlled by timers & pull switches and combinations thereof.

So, if you have mould etc in your kitchen / bathroom, despite having an extractor fitted, almost guaranteed it would have been the £10 model from the local electrical factors or DIY store. So I would recommend that you look to replace it with a good quality fan that actually works rather than just making some noise.

I will be replacing mine at home very soon. I will have a standard fan in the upstairs bathroom (as this is an ensuite and also made of breathable materials) and a dMEV in the downstairs bathroom that can run continuously. The downstairs room is more prone to mould as it is less well insulated and more heavily used, hence the decision. I will be changing the one upstairs myself as it is a simple case of changing leads over from one unit to the other, but the downstairs one is currently operated by the light switch and so we will need to get a continuous live feed into this. Probably a simple job, but not being a 'sparky', I would prefer the confidence that a professional brings to the task.

So, as ever, it seems like you get what you pay for. So as a special note for people living in older properties. We have spent much of the past decade sealing up houses in the name of energy efficiency and carbon savings. This has meant that many of the sources of fresh air have gone and we are living more and more in warm, humid and still environments. This is not good for your health or for the health of the building. We need ventilation. We need fresh air. We need to remove warm moist air in order to reduce the risk of mould growth. So look to get a good working ventilation system in place at home. This starts with mechanical extract from high risk zones like bathrooms, toilets. kitchens and utility rooms.

Get good fans that actually work.

What is the Whole House Approach?

A house is a structure embracing complex systems, embodied history and knowledge, not to mention humans!

We tend to think of houses as being simple structures that provide shelter, security and a place to call home. However, they are in fact, much more than this.

First of all, houses are products of geography, history and society. Geography has dictated the form of many buildings. Think of the different materials that have been used to form buildings in the past. I grew up in Wiltshire where thatch is quite common and there are even some chalk rammed earth houses. Now living in Wales I am surrounded by stone houses.

Geography also places a different set of pressures on buildings. Exposure in areas like west Wales and Scotland is unlike that faced by East Anglia or Kent. Buildings reflect the needs that the weather and topography place upon them. 

History has had wide ranging impacts on buildings. This might be the type of human activity that has taken place in the area (farming, industry, maritime etc), the effects of war and natural disasters, ..... Advances in science have facilitated change by the development of construction materials coupled with advancing building techniques and machinery. Globalisation and the role of the market have also altered how, why, where and what we build. 

Social pressures have also influenced buildings. Where once we would never have dreamed that it was safe or hygienic to have toilets in the house, we are expect new houses to have en-suite bathrooms.

The points above, are only the briefest because the topic is huge, but the principles are there. Houses represent a physical point in time that reflects their origins, but they also then continue to amass these markers in time. People extend and demolish, redecorate, add and remove services, change functionality, follow fashion, .... Each of these changes leaves a mark.

These marks are important. They are largely guided not by specialists. but by individuals. The decisions that have been made are not always the right ones, nor are they always done to a high enough standard. The decisions and their execution are again complex in nature. They are driven by different forces: economics, knowledge, skills, tradition, fashion, material science, ....

So when are are faced with new pressures in the world like: climate change; austerity; fuel poverty; wealth creation these will have an effect, for better or worse, on our buildings. For example, the past few years the main driving factor has been the encouragement to make buildings more energy efficient. This is no bad thing, however we have undertaken this task with self attached blinkers. Everything has been designed with one thought in mind, to reduce carbon and fuel consumption. This in turn has led to serious mistakes and huge amounts of wasted resources both in terms of physical, mental and economic waste. We are now taking out Cavity Wall Insulation (CWI) where is was put into narrow cavities, or into houses in exposed areas of the country, or where is was done without undertaking necessary repairs prior to installation. I fear (and know) that we shall be doing the same with External Wall Insulation (EWI) and Internal Wall Insulation (IWI) in years to come too. All for the same basic reasons: wrong materials used, poor craftsmanship applied, tunnel vision in the design stage, time pressures, funding requirements.

So can a different Whole House Approach (WHA) work and what is it?

The WHA is all about understanding a building, assessing the risks of different solutions, addressing the needs of the occupants (both now and for the future), making recommendations that can be explained and justified, ensuring that the craftsmanship and systems used are of a high enough standard. Ideally the building is also monitored and assessed into the future so that changes can be fine-tuned and lessons learnt and shared.

Building Surveyors should be able to assess a building independently and accurately. However, we need to ensure that they are not taking the easy route and one that leaves stones unturned. It is worth reading my earlier post about the Home Buyers Report and its potential to leave important factors like damp in the hands of 'interested profit making parties'.

Owners need to understand their properties - ain't that a can of worms! Ideally this should be taught in schools, but for now we have to rely on Building Surveyors (and RICS) and the power of the internet to inform.

We also need to have skilled and knowledgeable builders, architects, planners, building control officers, maintenance teams, ....... Yet another can'o'worms! The trouble here is that it does take a really strong and courageous person at the moment to make decisions that are ultimately correct, but that currently fly against the prevailing modus operandii of the construction industry.

For this to change we need changes in regulation, standards and decision making tools. Now that DECC has gone this might mean that a lot of changes that are in the pipeline might get lost, or it might be that the new Department for Business, Energy and Industrial Strategy drives this forward with new vigour! Time will tell.

Anyhow, back to what is the Whole House Approach!!

The WHA is about looking at all the factors that effect a building. We need to address and assess the risks associated with:

Underpinning Structure - What is it? What is it made from? How well was it made? What orientation is it?

Design - Does the building work well? Is easy to maintain? Is it accessible? Is it easy to navigate? 

Social factors - Is it noisy? Do smells waft into un-wanted places? Is it easy to clean? How will any changes reflect in the appearance of the building?

Energy efficiency - Is it easy / cheap to heat? Will it require cooling? Where is the heat lost / gained?

Energy generation - Can the building generate energy? Which technology is best for particular building?

Moisture movement - Is there damp? Will changes introduce damp? How is moisture managed?

Ventilation - Is there sufficient fresh air? Is the fresh air fresh?

Material compatibility - Can we use standard materials or do we need specialist ones?

Water efficiency - Can we reduce water use?

Monitoring - Can systems be used to help owners monitor and reduce resource consumption?

Maintenance - Can low maintenance be created? How can alerts be created to trigger responses to need?

Preservation - Do certain features need to be preserved / protected?

External environmental factors - How exposed is the building? Is there a flood risk? How will it perform in a warming world with more extremes of weather?

External social factors - Is there a skilled workforce available? Are the materials available locally?

....

Starting to get the picture?

The main complicating factor is that all of these are interlinked. 

For example, by wishing to improve the energy efficiency of a wall it will generally require the addition of insulation. This then creates RISKS. Is it compatible with the existing structure? Will it effect the appearance of the building? Will it introduce damp? Will it change the way the ventilation system works? Will it need maintaining? What happens if it put in by low skilled workers? Can you preserve wanted features? When will it be done?

After all of these questions are answered it may be that the better (lower risk) solution is to generate energy instead of saving it. But this needs to assessed and a reasoned solution presented.

So will this work? 

The main point behind the WHA is one that minimises the risk associated with proposed changes. Once we can understand the risks, we can assess them and make informed and hopefully rational decisions. This does not mean that it is a recipe for doing nothing, just that we might make fewer long term and costly errors.

A WHA therefore needs really well informed professionals who are independent, have time to make recommendations, have back-up of accepted knowledge and standards, but most importantly have the support of owners of buildings who wish to create a long-term future for their investment. A start has been made on this process by the STBA and you can access their Responsible Retrofit Wheel free of charge.

Love a real fire?

Image from Burley Stoves

Wood burning stoves are gaining in popularity. Good thing too. However, you need to know more than just that you want to have a carbon neutral energy source.

Efficiency. The efficiencies of wood stoves vary tremendously. The design of stoves go from the simplest grates to the more complex second burn options. Most are now rated and so look out for those that give the better rates.

Cleanliness. Hand in hand with efficiencies go the amount of soot produced. More efficient burns create less soot, so again if you don't want to be emptying out large amounts of waste, look for high efficiency stoves.

Drying wood. Wood needs to be dry before being burned and so you may well need to store wood so that it can air dry. This requires space and some sort of system so that you can have a stack of wood drying and another ready to burn.

Source of wood. Great if you have a source of natural wood, but if you are going to be burning waste wood you need to be aware that there is a bit of work required to get it ready for burning (removing nails etc). Also different woods burn at different temperatures. Wood like oak, blackthorn are great for burning, but birch, lime and pine are not so great. Check out: http://www.firewood.co.uk/heating-qualities/

Location of stove. Ideally the stove will be away from a wall and air will be able to circulate around it freely. This will allow the maximum amount of heat to be transferred to the room.

Air for burning. If you have stove that takes air from the room you will be encouraging colder fresh air into the house (in fact you will need to have external ventilation into the room). Also if you are using the stove as secondary heating you will be drawing your heated air into the stove and straight up the flue! So it is much better to draw fresh air into the stove directly from outside using a dedicated air inlet. Many new stoves have this capacity for a direct air inlet, but the older ones do not. By using fresh air from outside you will make your stove much more efficient.

Stove fans. If you have your stove set into the chimney breast then you may wish to look at a stove fan. These are powered by the heat of the stove itself and help to circulate the warm air around the room. They are expensive, but do work well.

Sizing. Think about what you will use the stove for. If it is just secondary heating then you will only need a small kW stove, but if you are to use it for heating the whole house then you will need to think about circulation of air as well as sizing. Too big a stove can overpower a room and make it unusable (unless you are into swimwear in the winter!) It may be better to have two smaller stoves in separate rooms etc. So care is needed here as it can be a bit of a balancing act.

Flue liners. There are two main grades of liners. Personally I would go for the higher grade as you will be peace of mind and a longer guarantee.

Installers. Always use a HETAS installer.

Carbon monoxide sensor. All stoves should be monitored by a working carbon monoxide alarm. No point having a lower carbon future if you are not here to enjoy it.

Sweeping. Check with you installer that the stove can be swept easily. This will need to be done annually on average.

Chimney pot. The pot should reduce the amount of water able to enter the system, so ensure that you have a cowl of some description. Do not fit cowls with fine grating as they can be blocked more easily. Again your installer should be able to advise.

So, have a think about these factors before you buy and fit a stove. Good luck!

Maintenance and the consumer society

One might think that with the growth of consumerism that we would naturally consume more maintenance products for our homes, but the trend seems to be the opposite.

The rush to be at the front of the queue for the latest gadgets etc does not sit well with the need for the regular and mundane nature of building maintenance. Checking whether you have cracked render, failed silicon around the windows, leaking gutters etc is not as glamorous as a new internet accessing tool.

So I often find that some houses with easily fixable problems (like many damp issues) get to the state where a 'damp proof expert' ends up recommending an expensive (and completely inappropriate) solution. These homes are often stuffed to the gunnels with disposable electronic kit, so there is not a lack of money, just a lack of priorities.

The 'quick fix' nature associated with modern consumerism doesn't help here either. Once people see that they have a problem any solution must be quick, cheap, no hassle, immediate, ... Unfortunately, due to the delay in acting they have often missed the boat. If maintenance is done regularly then you can use quick fix solutions. For example:

If you see that your silicon has failed around the windows, then it is a quick job to remove the old and replace with new. This will stop any more water getting into the structure. Simple. However, because people don't do this, the first they will know will be when damp has penetrated through the structure and the plaster inside has failed. This then becomes a job that might involve replastering, redecorating etc.

Exmaple #2: If you see that the ventilation grills on your ground floor are becoming blocked, just clean them up. Simple. If you don't then your solum (underfloor area between the wooden floor and the earth) won't work properly and eventually the floor joists will start to rot etc. This then becomes a major job. It will also take a nasty turn, as the builder coming in will fill your mind with having the floor replaced with a concrete one. This will of course be maintenance free!!! Naturally the new concrete floor with cause a range of new damp problems, ..........

So take a break from the computer / curved screen TV / smarter (than 6 months ago) phone and get outside and have a look at your biggest ever investment and give it a few precious minutes of your time. This will save you a lot of heartbreak, money and time resources in the long term. A few basic tools will allow you to do most of the work yourself (or it will be cheap for a good handyperson to fix for you). Houses are not as addictive as modern consumerist stuff, but they can a real drain on your resources if you ignore them for too long.

I would recommend checking the following:

Windows and door seals (esp. those facing the prevailing winds)

Guttering

Renders / pointing (again esp. those facing the wind and rain)

Drains around the house (to ensure that water is being taken away from the walls)

The roof (to spot any broken or slipped tiles)

Vents and extracts (clear to ensure that they are working properly)

I reckon that a thorough check will take around 5 or 10 mins. 

Then it is a case of keeping your eyes, nose and ears open for any changes. A new drip might be the first sign of a guttering issue. A small damp patch might indicate the need for a check of the seals around the window. A musty smell might alert you to a blocked vent, ....

So when you look at it this way, actually you can fit in all the consumerist stuff that you like and some basic checks on your home. For more guidance on maintenance, especially on older properties have a look at Cadw's Maintenance Matters website.

New Solid Wall Insulation Guide

Bristol City Council came to the Sustainable Traditional Buildings Alliance (the STBA) to address the issues associated with the Solid Wall Insulation (SWI) works that they were doing. The video and associated tools (that can be found at https://warmupbristol.co.uk/content/planning-guidance-your-home) have been developed to help locals find out about solid wall insulation (SWI) and the issues associated with it.

As you will know we are board members of the STBA and so have a keen understanding of the issues around SWI. So we recommend that anyone thinking about SWI should have a look at the video made for the Bristol as certainly many areas of Wales are in a similar climate / weather pattern to those living over the channel.

Getting the balance right is really, really important and the whole house approach is one that we have been delivering on for many years. With Bristol taking the lead we hope that many councils in Wales will learn from this ground breaking work and adopt a similar approach.

We really need Building Control, Planners as well as Architects and Builders to get onboard with this knowledge and concept. Without their buy-in it is difficult for owners of houses to enact on the best advice. Our focus on energy only is ruining houses and homes and we need to stop, take a breath and really look at each house individually.

Assessing the structure, materials, occupation, context and character of a building is MORE important that just looking at how much energy it is predicted to use (by using inaccurate EPCs). We need to ensure that the integrity of the house is improved by addressing ventilation, material compatibility etc otherwise we will end up damaging the health of the structure and its occupants. That is a waste of resources, money and ultimately will not address the underpinning threat of climate change.

So if you are thinking about refurbishing your home and want an independent assessment of what to do, what the risks are, what materials will minimise impacts on your health etc etc then give us a call at the Eco Home Centre.

What constitutes a 'healthy' home?

Health is really important to all of us, yet many of us live in houses with poor internal environments. Some of this is our own fault - we clean using dangerous chemicals; we allow properties to get into a poor state and hence introduce damp from rain; we don't ventilate properly; etc. However, some of it down to the structure of the building. So I thought that it might be worth investigating the idea that using health as opposed to pure energy efficiency could be a way forward for improvements in the housing sector.

So what are the key health factors that could be used to drive new specifications for home improvements?

Allergies

People seem to be getting more sensitive to substances, many of which are airborne. So there is a need for better Internal Air Quality (IAQ) in our homes. Having filters in ventilation systems is an obvious way of improving the situation for cleaning any air coming into our homes, however most properties do not have whole house ventilation systems, but there is a trend towards positive pressure ventilation in retrofits. These units can have filters fitted, but it does mean that they have to be cleaned / maintained on a regular basis and so this means that we have to have a system in place to ensure that this actually happens (otherwise it is waste of money and resources).

Many materials continue to off gas substances throughout their lives, so it usually better to use natural materials that have been treated with natural preservatives / protecting coats.

The main source of allergies, though comes through from our foods and the effects of our lifestyle choices. This could be the type of cleaning materials that we use, whether we smoke in the house etc.

However we can reduce dust circulation by using radiant wall heating rather than conventional radiators or underfloor heating.

Respiratory diseases

Respiratory problems are caused by a range of root causes many of which can be tackled during refurbishment. Issues like high / low humidity, mould and dust can all be effected by what we do to our homes.

It is really important that we manage ventilation in our homes as this helps to control humidity, but it is equally important that we allow any breathing walls to continue to do so. Sealing up older 'moist' walls can introduce damp and hence mould etc. Having a relative humidity of between 50 and 60 per cent minimises the risks associated with dust mites etc and this range can be maintained by the use breathable solid walls. We must also be careful when installing insulation, as poor fitting / specification can introduce cold spots and this in turn can easily create damp / mould issues.

Automatic ventilation control systems that run off information like relative humidity and CO2 levels can really assist with maintaining a good internal air quality. These can be installed where there is a good airtightness in the building and ideally systems would also have heat recovery built in.

Temperature related troubles

Overheating and underheating can cause or exacerbate serious medical conditions, so again we must ensure that properties do not get too hot, or too cold. So design is really important to make sure that properties can cope with the projected changes in climate which suggest that our weather will get more extreme in the future, especially with hot conditions. Unless of course the Atlantic Conveyor gives in and we might then become much, much colder in the winter.

So must ensure that properties are designed for both. Using high thermal capacity insulations like woodfibre boards and batts can assist with this. Being able to create homes that can easily and cheaply maintain a comfortable 19 degrees C in both summer and winter is important.

Highly efficient heating systems need to be used that are appropriate for the type of house, so care is required to specify the best type of system. Some houses only served by oil and electricity, others gas etc, so the most efficient systems need to be specified and this might involve additional works. For example ground source heat pumps (GSHP) only work well at low temperatures and so a well insulated house with managed ventilation is required here. A very efficient GSHP in a poorly insulated and draughty home will be very inefficient.

Mental health

Now this is a real bag of worms. Issues like stress can come from a wide range of factors that can be designed out (or into) our buildings. Common factors that effect stress at home include:

Money worries - making our homes cheap to run is really important (as long as we don't cause lots of 'unintended consequences' at the same time). So installing systems that improve energy efficiency, reduce water consumption, minimise maintenance costs, prolong maintenance intervals etc. is really important. Renewable energy systems that attract support can also help to relieve financial pressures by providing some free energy, but also a small income. However, it should be remembered that people make choices when it comes to spending their money and it may be that the best ones are not always taken.

Families - families don't always get along and having separate spaces can be useful. Knocking through reception rooms to make large spaces may not be the best solution. Sound proofing between rooms is also important to create more private space. Having bedrooms that are acoustically isolated can make sleep better and this can be really important.

Neighbours - again neighbours can be a source of comfort or stress. Whichever it is, having good acoustic barriers between the two houses is important. It is also important that any thermal improvements to one house do not cause problems with any adjoining property. So care needs to be taken here.

Natural light - a lack of natural light effects many people, especially those suffering from SAD and so it is important to ensure that light is maximised. This might mean using sun tubes, roof windows etc.

Worries about safety and security - using good quality doors, windows and fixings, combined with clever design can create homes that both feel, and are, more secure. 

Alleviation of niggles - of course there are no end of these, but some are avoidable: Alleviating pressure drops in hot water when more than two outlets are being used; use of long life bulbs to reduce need for replacement; easy access to water stop-cocks if there is a major leak; isolation valves on water outlets for easy routine maintenance; use of siphon toilets rather than valve to stop constant leaks; use of metal rainwater goods to reduce water damage from leaking or damaged plastic ones; use of breathable paints on breathable walls to reduce re-painting requirements; no drylining allowed to reduce issues associated with just hiding problems etc etc.

Conclusion

When we start to think about our homes in more detail one realises that we need homes that feature:

• Good, well controlled, ventilation (e.g using CO2 and RH controls)
• Appropriately insulated both against heat loss but also heat gain (e.g  use of wood fibre insulation)
• Minimised the use of water (e.g pulse shower heads, variable siphon flushes etc.)
• Take advantage of any appropriate renewable energy generation potential (e.g FiT and RHI measures)
• Minimised use of energy (e.g LED lights)
• Have good acoustic insulation both between houses and within them (especially bedrooms)
• Have a mix of private and public space 
• Have sufficient natural light (e.g using sun tubes etc.)
• Are free from risk of damp and mould (using correct breathable materials)
• Use natural materials that are less likely to off gas toxic substances (e.g wood)
• Use materials cleverly to minimise maintenance requirements (check compatibility of materials)
• Use good quality materials that provide long term solutions to safety and security (good quality doors, windows and locks)

Now all of that is a tad more involved than indiscriminately slapping on EPS external wall insulation and changing a boiler, however if we start to think more about maintaining a good, healthy internal environment then maybe we can reduce costs on the health service as well as providing better housing for the great British public.

The British Thoractic Society estimates overall costs to the country of £6.6 billion due to respiratory disease (or which Gov. says £1 billion is spent annually by the NHS on chronic obstructive Pulmonary Diseases)

The NHS has figures of around 31,000 cold related deaths in 2012-13.

The NHS also has a plan in place for heat related illnesses. (pdf format)

The NHS also spends around £16 billion on stress and anxiety related illnesses annually (pdf file).

So improving our homes will not eradicate these costs, but it will have some effect. So we can either look to continue doing 'improvements' that only tackle a small fraction of the issues facing our stock (and even this we are doing badly in many cases - and this causes more stress and more long term financial costs to the country) or we can start to create a nation of healthy homes.

Damp proofing a typical Welsh terrace wall

Typical streetscape in Cardiff

Can you stop stone and brick walls from getting damp?

The simple answer is YES, but there are a range of issues surrounding the question and the answer!

The main issue around whether a wall is damp or not is that diagnosing damp is an art not a science per se. Common damp meters use electrical resistance to measure damp and this is fine for timbers, but for walls it requires a lot of interpretation. High readings can come from salts in mortars, old lead based paint etc, so not always water. So where you take measurements can radically affect the advice that you are given. So some companies who are trying to sell you damp proofing measures can use these meters to show that you need treatment when you might not.

So that's the issue with defining whether you have damp, but assuming that you do actually have a damp problem the next issue is where is it coming from.

We have all heard of rising damp, but many houses in Wales suffer from penetrating damp. This is water that is blown, or diverted into the structure. This can be through cracks in pointing, cracks in render, leaking rainwater goods, blocked guttering, failed seals around doors and windows, ...

Damp can also be caused by condensation. This might be due to poor heating, ventilation, high humidity from indoor activities. Again this needs to be assessed by looking at heating and ventilation strategies and infrastructure. Do the windows have trickle vents, have the chimneys been blocked??

Rising damp might be due to a range of factors including external ground levels, the presence of replacement concrete floors, blocked under floor ventilation, ... 

As you can see, damp can be difficult to diagnose. However, it is really important to ascertain where the source of any unwanted water is coming from.

Once you know what the problem is, you can start to find the cure. However, the cure will be influenced by the history of the building and the materials that were used to built it in the first place. This means the make up of the basic structure and also the materials used to repair, maintain and develop it over time. This building pathology work is key to refining the diagnosis and will hence help lead to an appropriate solution being found.

I cannot go into any great detail here as each building is different and requires specialist individual advice. However, the question was is it possible to damp proof these old buildings. The answer you might remember was yes, so what are the solutions?

1. Rising damp

If you do indeed have rising damp then you might need to:

• Lower the external ground level
• Re-instate ventilation under the floor boards
• Remove cement render from the outer walls
• Re-point the bricks / stone with a lime mortar
• Re-render using a lime render

All of these are potentially permanent solutions, however they are fairly major bits of work, so most people just want to inject something into the wall. This is potentially possible and it depends on a range of factors, one of which is whether the wall is made from solid brick or stone. These walls are fundamentally different in their nature and it is easier to apply modern injection treatments to brick walls. 

Damp that is rising in a brick wall can be treated quite effectively using creams like DryZone. However even here you see companies injecting the damp proof cream into the bricks rather than the mortar. So with care this type of product can be part of a solution (but not if your damp is due to condensation or penetrating damp). However it won't work in stone walls (unless you have an even mortar bed at the correct height - like in ashlar walls).

Stone walls are fundamentally 'moist' in nature and so need a more holistic approach that is based on material science. The solutions here are much more likely to follow the bullet pointed measures above. It might also need to be combined with addressing ventilation issues, as stone walls need to dry out by the movement of water from the water to the outer and inner surface. 

2. Condensation

This tends to be more due to high humidity in the building and so a balance needs to be found between energy efficiency, ventilation, insulation and behaviour. It may be that a house needs positive input ventilation, or that the old chimneys need to be unblocked and vented, trickle vents on windows need to be opened, humidity controlled extractors fitted, or just a clothes dryer installed in the garden / room with an extractor fan. 

3. Penetrating damp

Penetrating damp is generally caused by issues around poor maintenance of a property. However, it can be down to the use of inappropriate materials like cement render. Seals like silicon around doors and windows fail over time and rainwater runs down the surfaces and straight behind the sill. Cement render (is fundamentally inappropriate, but nevertheless covers the majority of stone and brick houses) cracks due to its brittle nature and traps water behind it. Gutters and downpipes need to be clear otherwise they can easily poor high volumes of water against (and into) walls. Poor drainage around the building can lead to water sitting against walls,  I could go on.....

As you can see, diagnosing damp and finding the correct solution is a bit more involved that just pumping in a load of chemicals. However, pumping in chemicals and using water proof cement is what we do in the UK to the vast majority of our solid walled houses. In fact many mortgage lenders insist on this type of damp treatment. What a shame, it is generally a complete waste of money and resources. A typical damp treatment costs around £4 to £5,000. Don't be fooled by guarantees and assurances, many are meaningless. A recent customer had a injected DPC installed and when it failed dismally she was told that it had been installed correctly and so she couldn't claim against the warranty!

We would always recommend that you use your money wisely and this means that it is better to find a permanent solution to damp. This requires time and knowledge to get to the correct diagnosis, It is not a quick trip around with a damp meter and a bill of £5,000. The answers are there, but you will generally need some independent guidance to find the right ones for you and the house.

Be Positive on Ventilation

From http://www.housebuildersupdate.co.uk/ the illustration shows air being drawn into the house from the eaves and then pumped around the 'whole' house and the warm moist air being pushed out of the building envelope 

Positive Input Ventilation (PIV) systems are now starting to be much better known. This may well be due to the profits that the companies are making from the installation of these types of systems across the UK by the social housing sector.

Many problems have been encountered by this sector and the private sector by the installation of energy saving measures. Sealing up houses with draught proofing, insulation, double glazing, new doors, removal of chimneys etc has meant that the warm moist air that we generate in our homes gets stuck inside. This high humidity means that the excess water has to go somewhere and this tends to be onto cold spots in the fabric of the building. The levels of condensation have radically increased and this leads to mould issues as well as potential rot etc.

So, the industry have come up with a technological fix in the form of PIV.

Basically the simplest form of PIV is where fresh air is drawn into the building using a fan and then pushed out (generally from a single point) into the house. The fans are designed to run constantly and so are low energy consumers and quiet (but I would always check their wattage and db levels before making your final choice) The lower humidity (and cooler air) then effectively 'waters down' the higher humidity air constantly by forcing it out through any cracks / trickle vents etc that are in the building.

Having a lower humidity in the house means that walls can dry out slowly and condensation problems can be eradicated. Lower humidity area is also easier to heat and so perversely the house can become warmer by having fresh air pumped into it. However there are some potential issues. The cool air has to come in somewhere and this immediate area will be cooler due to this. So it is important to locate the input vent well. The higher pressure created by the fan will force air out from the easiest locations (out through extraction fans, trickle vents, ill fitting windows etc.) and so the benefits of installation might not be felt throughout the house. This is especially important when one thinks that most of these are installed through the first floor ceiling and many houses have most of the humidity in the ground floor kitchens, bathrooms etc. Having doors open creates better air flow but might not be practical where noise, smells, privacy etc require doors to be closed. So care is required when assessing the suitability of the product to your particular situation.

PIVs can be fitted as a DIY project, but there are a few horror stories where people have found that it is better to bite the bullet and get one of the manufacturers to install it for you. At least then you get piece of mind, a guarantee / warranty etc.

Whilst I see PIV as a potentially viable sticking plaster for homes, I would always aim to tackle the fundamental causes of damp / mould by using appropriate materials and ventilation strategies. However, in an imperfect world, the cost of installing a PIV system (around £700 - £900 fully installed price or £300 just for the machinery) may well be sticking plaster that you need.

There are, of course, variants within the PIV world, so you can have multiple output vents, integral heaters, automatic controllers, etc, etc. Of course, the more you pay then the better the controllability of the system, etc. So again you will need to assess which system suits you best. The specifiers / engineers from the various companies should be able to assist with this choice.

The best well known PIV systems come from Nuaire and Envirovent, but all the main ventilation companies produce their own versions.

Good luck.

Where has that damp smell gone?

No need for these now!

The was always a certain smell when we came back home. That slight dusky smell that reminds you that there was damp in the house. Well, I am glad to say that when we returned from being away at Christmas there was no such gentle reminder.

The mould that has been growing (thanks to the original builders who left the house renderless and with some major defects exposed to some pretty awful weather in the late summer) has been stopped in its tracks. Now, all I need to do is to repaint all the internal areas that have lost their paint / been affected by mould etc.

I am really pleased that our efforts (and that of Welsh Lime Works) have paid off.

In summary we have:

1. Created a drain all around the building so lower the external ground level - this will allow any moisture from the ground to be vented off before reaching internal floor levels

2. Opened up a blocked chimney on the first floor to create a better airflow through the house (the ground floor chimneys house wood burning stoves and so are already open)

3. Removed the cement render from the solid walled and early cavity walled elements of the house and replaced this with a lime putty / limestone dust render. Finished with a white limewash (applied in a hot mix)

4. I have also reset all the guttering to ensure that it is not leaking anywhere

So effectively the house is now functioning as closely to its original design as it is economically viable to do (note that we have not replaced the cement floors with the original suspended floors).

We have experienced some pretty wet weather at times since the work was finished and it should be noted that some areas (concrete block substrate) is still drying out, but the internal walls are now dry and the render is slowly releasing all the trapped water to the outside. 

I had imagined that the drying process would take a lot longer, given that the walls were exposed for so long and that the limewash was only put on late last year, but the project has worked really well and we now have a dry and smell free home. So all bodes well for the future as, apart from routine maintenance on gutters etc, the actual structure of the building is now working in a way that will keep the whole house dry inside for many decades to come. I am expecting that I will need to re-limewash every 6-8 years one the southern and western elevations, but more like every 10-15 years to the north and east (and this is down more to issues of traffic fumes rather than the weather).

Given that I have seen replacement cement render failure in a significant number of solid walled houses within a year of application I think that the added expense of doing it right will soon pay off. It really is a false economy to use cheap materials when all you do is store up more hassle and expense for a future date. So, if you have an old house with a damp problem why not give us a call and we can help you out.

Extractors and wind

Most extractor fans come with a basic louvres system to reduce back draughts

Most houses have extract fans fitted to them, mostly in our bathrooms and kitchens. However, we rarely think about which way they are facing. Most commonly they are fitted to the nearest wall, simple.

The UK is one of the windiest countries in the world and so the chances are that the prevailing wind will have a large influence on the effectiveness of the extractor, especially if it is facing west. Anyone who has a west facing extractor will be very aware of the level of noise generated by flapping louvres and also by back draughts and the inability of the fan to clear the room of water vapour. So, if possible fit fans away from the prevailing wind so that they can function properly and quietly.

Fitting fans to the lee sides of a building is not always possible, so what to do then?

There are a couple of solutions, firstly you could fix an in-line back draught shutter system. I haven't tried these myself, but they are on the market and should provide you with some protection, however if the fan is on and the wind blowing then my money is on the wind winning! One also fears that they too might suffer from acoustic issues.

Back draught shutters can be used to create a better solution but may still rattle around and also be blown shut when trying to extract

The system that I have used at home is to replace the louvres with a louvres and hood combo. This has altered how the system works quite dramatically for us. The two bathrooms are much quieter and the fan seems to be more effective.

The basics are that the fan can now work without fighting the wind so much and also that the protection stops the rattling of the louvres as the pressure changes due to the wind are now just coming from below. It also has the advantage of protecting the vent from the rain more.

A simple hood to go over the louvres can help reduce noise and also protect against wind driven rain

So it is worth having a think about extractors and how well they are working and what, if anything, can be done to improve their efficacy.

Ventilation vs Energy Efficiency

Ventilation does not mean uncontrolled draughts!

Ventilation is key for all buildings, after all we do need a bit of the fresh air stuff to stay alive! However for older buildings it is even more important. Solid walled buildings should be regarded as having 'moist' walls and hence they dry to the inside as well as the out (assuming that they have not been covered with cement render!) They therefore allow moisture into the internal environment and this needs to be wicked away along with all the moisture that we bring into our homes.

To illustrate this one study found that in a house we produce the following daily:

1.25 litres per person (just by breathing and sweating)

2.40 litres by showering, bathing etc

1.75 litres from a gas oven

1.00 litres from plants (assuming 25-30 plants per house)

....

So we are looking at around 10 litres of water per day from a family of four. All this water needs to be removed from the house and this requires ventilation.

Understanding how this works is really important, but actually very difficult. Where does the fresh air come from? Draughts around doors and windows? Chimneys? Punctures through the walls that have been poorly sealed? Where does it leave the house? Mechanical extracts? Chimneys? Trickle vents? Windows? Lofts?

Housing Associations and others are now wising up to the need for ventilation (after all many of their complaints are about damp and mould). Most are now fitting 2 x low energy vents in houses that run constantly. These only cost around £5 a year to run and can help tremendously with ventilation, but still people will turn them off! This is because people associate ventilation with increased energy consumption and hence costs.

Energy efficiency though is affected by poor ventilation. If walls are wet due to poor ventilation then the walls will be less efficient (by a factor of around 30%). So actually having good ventilation can help with energy efficiency. However most importantly ventilation is important for the health of the occupants and the health of the building itself. Without ventilation we are more likely to end up with mould and damp issues and this then leads to additional expense dealing with this. So it is a false economy in not venting well.

Ventilation is therefore linked to energy efficiency in several ways
So how to go about this?

Well there is no easy answer as each house is different (construction, levels of moisture, knowledge of occupants, lifestyles etc etc). So the best way is to use tools that measure what is actually happening and then automatically adjust ventilation rates.

Modern systems monitor and control a range of factors like temperature, humidity and CO2

These systems are not cheap and generally require a whole house solution with heat recovery (MVHR). These systems require vents to be placed in each room for either extract or input (or both). These are then combined (via ventilation ducts) in a central unit where the outgoing warm moist air help to pre-warm the incoming fresh air. These systems can work really well, but they need the house to be well sealed before they are fitted. They also require the ducts to be passed through the house etc. So these are quite complicated systems, but certainly the most effective as they help save the warm air in the house and therefore are more energy efficient.

Older houses of course are more difficult as they are harder to make airtight. However due to improvements over time many of these houses are now lacking in ventilation. People have fitted doubled glazed windows and doors (many of which have not had trickle vents specified), chimneys have been blocked up, suspended floors have been replaced with solid, lofts have been insulated, hatches draught proofed etc.

This has meant that whilst many houses do not have the required airtightness for efficient MVHR they are lacking in the required background ventilation to remove the 10 litres of water a day needed. Rock and a hard place territory!

So the exercise becomes a little vague and distinctly difficult, especially where people are not used to having (or paying for) pressure tests on their homes. So we are in the territory of 'guestimating'. This is not ideal, but it is really poorly understood area of housing. So you may well find that you are the best person to make decisions on this, after all you will know how bad issues like condensation, mould and stale air are in the house and whereabouts it occurs most and when. So spend a little time thinking about where any problems are and what the root cause may be.

Windows and trickle vents
Chimneys and vents
Draught proofing measures
Extract fans and their direction of venting
Floor ventilation
Airflow in and between rooms (is furniture hard against walls? Is there an airgap at the top or bottom of internal doors? Are certain areas sealed off from the rest of the building?)
Functions of rooms (bedrooms, kitchens and bathrooms are subject to high humidity)
Thermal bridging / cold spots (these attract condensation)

Uncontrolled ventilation via major draughts around doors and windows, floors etc is not the answer though. This can be a real drain on resources as you cannot adjust the airflow to meet the ventilation needs of the building, so make sure that any major draughts are dealt with properly, but be aware that by reducing the uncontrolled airflow that you should be thinking about installing controllable airflow. For example, if you are replacing some old draughty windows then replace them with well sealed units that have adjustable trickle vents on.

Many social housing providers now also fit Positive Input Ventilation systems to reduce humidity levels in their houses. These systems can be simple and easy to install in houses with lofts. Basically they pump air from the loft into the house constantly and the warm moist air is pushed out of the various holes in the housing envelope. They have had a variety of reviews, but those houses that suffer most from high humidity / condensation issues seem to see the best results. I may well try a system in my house and then I can speak with a bit more authority!

Personally I think that buildings need to have:

- extracts in the main moisture generating areas, i.e. kitchen and bathrooms (these should be through walls that are not subjected to the prevailing winds and where this is necessary they should have vent covers installed).
- background trickle vents in windows
- where no trickle vents then 2 x background vents should be installed, ideally these will be heat recovery units that can exchange warmth from the stale air and impart it to the incoming fresh air
- all chimneys should be vented (both at the top and at each breast)
- ideally the whole wall structure should still be breathable
- suspended floors should be vented correctly
- all loft space should be vented correctly
- potentially a Positive Ventilation System installed

This should be treated as guidance to minimise the risks associated with poor ventilation. Most importantly remember that ventilation is not an 'enemy' of energy efficiency. It is a requirement of a healthy house.

Check your extractors

A problem that is easy to miss

Many homes now have bathroom extractors that feed through the loft space and out through vents. This system has some advantages over systems that go straight through walls, but having just been in a house in Penarth there are some disadvantages as well!

The vents are commonly joined together using tape, but this tape is subject to a wide range of pressures and temperatures which can cause some cheap tapes to fail. What sort of tape do you think is used for most joint sealing? High quality tapes designed for high temperature range conditions or standard duct tape?

So this is the problem, What happens if the tubes that are meant to be feeding warm moist air to the eave or roof vent are actually feeding this same air into the cold loft space? Lots of moist air condensing on the cold felt and timbers.

The rafters in the attic I was in were very damp and it felt very muggy, so drastic action to reduce the amount of water in the structure is needed. Having put the extracts back together I also noticed that the well insulated loft space had been done in such a manner to block the eave ventilation. So this had compounded the problem.

Ventilation is often seen as the antithesis of energy efficiency, but actually you need good ventilation to keep buildings and people healthy. There is a balance to be struck. Maintaining good levels of ventilation is as important as creating an insulated fabric, especially in older buildings where the actual breathable fabric may also need its own ventilation to keep dry.

With most housing problems it comes down to maintenance and being aware of how your building works. Neither of these two factors are glamorous, but they are both essential if we are to have a healthy built environment. So check your vents, especially in areas where you rarely go.

One last note - try to fix vents on elevations that are away from the prevailing winds - the wind will just blow the louvres shut and make it ineffective. You might also think about alternatives to the £20 standard vents. How about one with a cover? Or one that is controlled by humidity levels, or potentially the ultimate where you have a room based heat recovery system!

Damp proofing cellars

Some old houses have partially buried walls

Like dealing with solid walls you have a couple of choices here when dealing with rooms that are below ground.

Choice 1 - Work with nature
Choice 2 - Try and work against nature

I am a Choice 1 type of guy, as nature will always find a way of getting through our defences. Ask King Canute!

So we are looking at solid walls that are porous and a subterranean location that may well be permanently damp. How to keep the cellar dry?

Well, this is a difficult aim to achieve with 100% success rate and I think really depends on each households sensibilities and access to a range of resources.

If you find that the walls are not very damp and that you are using the space as a typical cellar function (i.e. there is no pressure on keeping the room totally damp free) then the walls may well be easily treated by using a breathable finish on the walls and ensuring a good air flow. So leaving the walls bare (or painted with a lime / clay / chalk paint) and having a good draught will allow any moisture coming through the walls to be vented away before presenting any problem. Note, though that furniture etc should not be placed too close to the wall as this will restrict air flow and could lead to mould formation.

If you want to use the room as a more conventional living space then keeping it dry gets more important. Having lots of ventilation in this type of room then gets more difficult as we are not so fond on a keen breeze around our ears! So how can we allow the walls to breathe whilst keeping damp at bay?

The way the English Heritage recommend is to use a dimpled membrane. Basically this is a plastic sheet that has dimples in that create a vented space around the wall. See below:

So the plastic keeps the damp away from your new wall, but what happens to the water?

Well this is where individual factors come into play. If the walls are really wet and literally running with water then you will need to install an internal drain rather than relying on ventilation only. This drain can be directed straight into the main drains, or it might need to be fed into a sump and then pumped out (via an automatic pumping system).

So the 'Heritage' system is a bit of a hybrid that wants to work with nature, but has to provide some very clear guidelines in which elements are not acceptable! Purists will no doubt say that it is case of using very breathable materials, drains and ventilation, however I feel that it is down (as ever) to the individual site conditions, usage patterns and sensibilities of the client.

MVHR insulation

I was in a meeting for the Existing Homes Alliance Cymru and we had a good presentation on the Project CALEBRE research from Loughborough University. One of the issues that they had in their work reminded me of another couple of cases I have seen with the installation of MVHR in homes. MVHR is Mechanical Ventilation Heat Recovery, so a system that ventilates your home with fresh air, but does so by using the warm and moist extracted air to pre-heat the incoming air.

One issue is that of insulation. In the Loughborough case, and in the two I have seen, the insulation was really poorly fitted around the ducting. It was there, but the corners were not covered properly and the pipe lengths were not wrapped up and sealed properly. This of course means that the warm air that you need to pre-heat the incoming air was not as warm as it could have been and also the then pre-warmed air was losing some of its heat in the loft space. So take care when having MVHR installed and make sure that you check the quality of the installation afterwards.

Two other issues emerged from the Loughborough study that are also really important.

1. It was found that the system was not calibrated correctly for the house as the installer did not check this until they were called back to sort the insulation problem. So it sounds as if this is not necessarily done as a matter of course. So ask your installer to check the settings once the system is up and running (with the insulation correctly fitted).

2. The cost savings that can accrue from using a MVHR do not kick in until you have a really airtight house. So unless you have an airtightness level of around 3 cubic metres per sq m per hour or better you will not get any carbon benefit. Having spoken to Ventilation companies they tend to state that MVHR can be installed in houses with an average 7 - 10 cubic metres per sq m per hour. Whilst this is true they can be fitted, it will not give you any cost or carbon benefit, so it is not worth while. Most new houses are built to a standard of 10 cubic metres per sq m per hour and so using MVHR in retrofit is really tricky to get right.