Measures working, but still more to do

Last year we spent a lot of time getting the walls of our home sorted. I dug a trench around the house and installed drainage to make sure that rainwater was taken away from the plot as quickly as possible. The walls were also stripped of their cement render and a lovely new render from Welsh Lime Works was applied.

So where are we now?

Out of the red and into the green

Well I went around the house yesterday to check moisture readings in the external walls and I am happy to announce that the levels are down from the mid 20% to around 10-13%.

So the external walls are drying out even now, despite have amount of water that was allowed into them after the cement render was removed and then the application process associated with the lime render. So great news!

However, the internal walls where concrete replacement floors have been installed are still wet. The lower part of the wall, where the waterproof render and plaster has been fitted is around 10%, but above the 1m mark where the original lime plaster is still intact is wet through (mid 20%s). I have been hoping that the silicon treatment that I installed would have had an effect by now, but it seems as if there is still water being sucked up by capillary action between the waterproofed render on the walls.

I think that I will have to inject more silicon cream into the mortar at the base of the walls to see if I can reduce the amount of water being drawn up. The water pressure that is created by replacement floors is amazing, but I have little choice as to the action I can take, bar cutting out the mortar and installing a physical DPC - lots of dust that the rest of the family might not appreciate!

So, good news on the main piece of work on the house, but still a little more to do to remove the issues created by blindly following the conventional damp industry and mortgage providers.

The importance of preparation for wood floors

Preparing floors can be time consuming and dusty task

Wooden floors are glorious things. They have beautiful feel that shows the history of the wood used and reflect the wonders of their individual growth and characteristics. However, if you are using a treatment (like the wonderful Osmo Polyx Oil) it is really important to get a consistent finish on the floor first. A typical application requires a final sand of around 120 grit.

If you don't get a consistent finish then the oil will not be absorbed evenly and this can lead to a number of problems. Recently a customer used new timber on their floor that had not been sanded over after laying. The timber had been put through a planer that had created different finishes on the planks. In some areas the timber had effectively been polished by the planer and in other areas the timber was still quite rough. The new Raw Polyx Oil was then applied.

The Raw product has a minimal amount of white pigment in it to counteract the honey effect associated with oil treatment. It is also designed to have no visible finish, thus making the wood appear to be untreated - raw, if you like.

What happened was that the rough areas allowed the product to 'pool'. This has led to these areas appearing to be milky as the pigment was concentrated in here. Also the polished areas retained their polished appearance as the oil could not be easily absorbed into the wood in these areas. The outcome has been a patchy mix of sheens and colours. Obviously not ideal on a lovely new oak floor.

So it is really important to ensure that the floor has been sanded consistently across the whole surface. Any product will then be absorbed into the timber in a regular manner and hence give an excellent and predictable finish. This is really important where you have a pigment / colour involved in the process.

So time spent in getting this right will bring rewards in the longer term, so build in the time and expense into your equations to allow for good preparation when renovating or installing a new wooden floor.

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.

Osmo White on White

Getting a lovely white finish to a floor can be a bit tricky and so here is a little tip that I gleamed from Osmo last week.

If you are wanting to get a 'pure' white finish on a floor it is better to use 'White on White' rather than 'Clear on White'. What this means is that it is better to use a white base colour and then top it with a white tinted top coat. If you put a clear on a white base then it can turn it slightly yellowy due to the oils in the clear.

So the recommended type of formula would be:

Osmo 3111 White Wood Wax  - Base Coat

Osmo 3040 White Tinted Polyx Oil - Top Coat

Note that it would be one coat of each maximum!

This combination will produce a lovely clean white finish and also quite a whitened effect.

Concrete floors - hate them!

Typical suggestion for a replacement concrete floor

My house is a very typical Victorian Welsh terrace. Solid walls made from a mix of local and imported stone, bricks around the windows, doors and chimney etc. It has also had the typical 'improvements' over time:

Replacement windows

Replacement stairs

Replacement tiles

Toilet moved inside

Rendered with a water proof concrete

Chimneys blocked and replaced with gas boiler and radiators 

etc etc

One of major changes was the replacement of the old suspended floor with a new concrete one. This is proving to be a real pain.

What happens when people replace a suspended floor is that they line the new floor with a Damp Proof Membrane (DPM) underneath and fold it up around the edges of each room. This is meant to tie in with a damp proof course (DPC) in the walls. Unfortunately this is a real weak point as injected DPCs are not very reliable (due to poor installation and not really being the ideal solution in the first place - but it is quick and cheap!) So what happens is that the damp (that was under the floor and previously being wicked away by a healthy draught under the floor boards) now has to find another way out. It does this be focusing on the internal (and external walls) through the foundations of the building. It is carried up by capillary action into the walls (this should be stopped in theory by the DPC, but often is not). If the old plaster was left there then it would travel through this and out into the internal environment (this is why internal ventilation in an old building is really important), however what happens is that the old plaster is removed and replaced with a water proof plaster. This effectively seals any water into the wall and hides it from view. Hooray!?!?

In my house what has happened is that this water has appeared above the new plaster and also crossed through it - water is a persistent beast. So it is my internal walls that are now giving me hassle. The external ones I have largely dealt with by removing the cement render and also creating a drainage channel around the house, but the internal ones!! I recently did a quick damp meter check on the walls and where the external walls are now giving me a figure of 7 - 10% damp but I am getting 30% on the internals. Needless to say the dehumidifier is running on our free PV electric during the day now to try and dry the walls out during the summer months. I will have to re-inject as well to try to slow the next batch of damp that will no doubt be keen to get into the walls. I might even bite the bullet and get a physical DPC installed. The dust, the dust!!

So as a word of advice don't install a concrete floor in an old house, refurbish the old suspended floor, insulate it, ensure that the vents are clear and working etc as it will save you a lot of headaches in the future. If you are really keen on removing the wooden floor then look at using a limecrete floor solution, anything but DPMs, DPCs and concrete!

Anti-slip treatment for wood flooring

Recently I had a query from a commercial company who had been having trouble with people putting in claims against them for injuries caused by slipping. So after a bit of research I found that slip resistance has a scale. The majority of domestic floor finishes have a rating of R9. Even many commercial products are a R9. Osmo Polyx Oil and the Osmo Pur fall into this category.

A bit more digging and I discovered that the insurance industry requires a R11 rated floor finish in order to cover injury claims against slippage. So the hunt was on to find a suitable R11 rated floor finish from an eco-friendly manufacturer.

Thankfully we are an Osmo stockist and despite a R11 rated finish not being available from Osmo UK, we managed to get a shipment across from Germany of the 3089 Hartwachs-Ol Anti-Rutsch Extra! This is a R11 finish and also based on natural oils (a la Polyx Oil). Unfortunately the paperwork that accompanies the product is only in German, but it is applied in the same way as the Polyx oil.

A permanent damp solution?

The history of my drive way next to the house has been a voyage of discovery thanks to my neighbour. I live at an end terrace and there is a shared driveway between it and next door. It is a concrete drive that butts right up against both houses.

Now this drive way was originally two garden paths and a stone wall, but it was converted to a driveway to open up access to the back. This is a fine thing, but it has been through a few changes over the years. I have been discovering these and the also living with some of the consequences.

The paths were not taken up, just tarmac put over the top. Several years later concrete was put directly onto the tarmac. Of course this should not be done as the tarmac disintegrates under the concrete, but more important for me was that the height of the roadway was now above the level of the floor in the house! No wonder we have damp in that wall.

So I have had to cut out the roadway using a disc cutter (a diamond blade worked a treat) to get a 'straight' edge. I marked out a line with chalk, but the dust from the cutter obscured this quite badly so care needs to be taken when doing this.

My attempt at a straight cut to make the initial trench at the side of the house

I then set about smashing up the concrete with the breaker I had hired. Fair Dos the breaker was great. However I discovered the tarmac. So my first pass with the cutter only got me through the concrete. The tarmac though had failed and so was quite easy to remove. I did though have to use the breaker again. After a third round of breaking and shovelling (well using a trowel) I eventually got to a difference of between 20cm and 10cm between the floor level and the outside ground. So I now have a 15cm drain between the road and the house.

The concrete road broke up nicely with the breaker

The work involved taking off the render off of the walls from this low level. Knocking this render off was really satisfying. You could also feel the walls breathing a great sigh of relief as the old render and road way were removed and bricks and stone exposed (with their sodden lime mortar!) Surprisingly the wall from the door back turned out to be a brick cavity wall! This is an 1880's house with solid stone walls at the front and back. Finding a brick wall was therefore quite strange.

The damp was in evidence when the road level had been lowered down

I then repaired the road way using a concrete mix to shore up the edges. I did this as the road despite being a good 5cm thick could have failed along the edge. I also then did a lime and cement mix for the base of the drain. This will allow any rainwater to flow down to the road and away from the house. I angled the drain so that any water is kept away from the wall. Using a lime mix was there to ensure that there was some breathability in the structure so that it was not just trapping ground water in the area next to the house. To give an extra bit of strength I used some lime tolerant mesh in the structure as this should give it a bit of extra stability and strength. The lime will also help ensure that there is no cracking since it can flex a bit unlike a pure cement mix.

The new trench was lined with mesh and then thinly covered with a lime rich cement

This shows the re-rendered wall, the exposed lower wall and the new lined trench

So the job looks OK now and the water is draining away nicely. Only time will tell if this is the long term solution to the damp in the wall, but already I can see the walls drying to the outside. Fingers crossed they will continue to dry now that they are not constantly damp from being under road level.

Paths and damp

One of the most common forms of damp in buildings can be quite difficult to diagnose. It revolves around floor levels.

If your external floor level is higher than your internal floor levels it can bridge across the damp proof course (if you have one) or if you have a solid walled buildings then the damp soil / path can help to trap moisture in the wall.

This can be a result of historical additions to the outside of the house. Often the height of the external ground has been increased by things like:

Installation of pathways
Pavements being re-laid on top of existing surfaces at an increased height
Raised beds being placed against walls
...

Is there a way out of this? Well the only real way of stopping this transmission of water into a wall is to remove the problem. This means lowering the external ground level by the wall. Ideally you need a minimum of 150mm / 6 inches of difference in height between the internal floor level / damp proof course and the ground level outside.

This can be mean digging out a trench around the house to remove the excess soil / pavements etc. If this causes a major issue externally then you will need to install a drain around the walls. You will need to backfill this with large stones so that there is adequate drainage for water to be taken away from the wall and also for air to circulate around the base of the wall and help to keep it dry.