Loft stilts can help increase levels of loft insulation

One of the major reasons why people don't insulate their lofts to the recommended 300mm depth is because they have used the space for storage.

This means that very often the loft has around 100mm of insulation and then boards on top of that which are piled high with old clothes, items waiting to be re- discovered for the Antiques Roadshow, etc. This level of insulation is not ideal and should preferably be increased to the 300mm. Loft insulation companies, however, are not in the business of moving things around for people, so if they find a full-ish attic they will not insulate it.

An easy DIY solution is therefore required. Thankfully there is an easy way to lift the storage level to give you the insulation level that you and your house deserve, whilst also maintaining a solid storage platform. Loft stilts are available from most large DIY stores. There are a few UK made manufacturers:

http://www.loftleg.com
http://loftstoragestilts.com/

So get ready for winter by ordering in some insulation (preferably some natural ones like hemp, sheep's wool or some recycled ones like Warmcel (paper), Non-Itch (plastic bottles) or Innotherm (cotton)), some loft stilts and some screws!

Remember if you do want some natural / recycled insulation, give us a call as we have access to some great trade deals. 029 20373094.

Smoky Chimney Solved

Last week I had my two chimneys lined as they were not drawing very well and some smoke was leaking into the upstairs room via the old chimney breast.

The house originally had three additional fires, one in the kitchen (removed when the extension was added) and two in the upstairs bedrooms. The upstairs ones have been blocked off. One bedroom has had its fireplace removed completely and the wall re-plastered, the one in the front bedroom is still open and is 'sealed' using a chimney balloon. This background is important for what happened next.

I booked in a specialist company to install the chimney lining. I was sure to pick the stronger liner with the 25 year guarantee (904) rather than the 10 year one (316) . Why would you want to save a couple of pounds on a radically inferior product? So note, the 10 year guarantee chimney liner is the industry standard!! So remember to ask for a 904 liner and get something that will last 2.5 times longer, otherwise you might be getting it all done again before you know it.

The liners were fixed to both downstairs wood burners and signed off with their HETAS certificates. Job was a good one.

With great expectation we lit the fire for the first time this week as it was a little colder outside, but mostly because of the fun of having a new chimney liner. It was with horror then that the house started to fill up to smoke. Arrgghhh.

I quickly traced the source to the upstairs front bedroom. All the doors / windows in the house were quickly opened fully. Boy did it smell! So called the installers, they suggested that it might be a 'cold chimney' where there was a thermal block and the smoke was backing up in the liner. Get it really hot and it should work again I was told. So I stoked up the fire and kept fingers crossed. It did slowly get better.

So a few days later, it was time to try again to see if the problem was still there. Sure enough it was, but this time there was much less smoke, but it was still originating from front bedroom. Back on the phone to the installer and they booked to come down in a couple of days time. That day was today and they took out the liner to see if there was a split in it. All fine. All connections tested again, all fine.

So the diagnosis? Well the only explanation was:

The new liner is touching the inner walls of the chimney and this was burning off the remnants of the tar / ash etc of the upstairs chimney and this was then creating all the acrid smoke that was then being forced down the blocked chimney and into the room. All makes sense, so they kindly swept the chimney to remove the excess tar etc and then we blocked the upstairs chimney flue from the bottom using glass fibre insulation. Any tar being burned off should therefore not have enough oxygen to burn and also any smoke should be stopped from entering the room by the compacted insulation. Once the tar in the immediate area of the new flue has been 'burned off' the problem should be over.

So a bit of an adventure, but having had a roaring fire in the stove this afternoon (despite it being nice and warm in Cardiff) I hope that the problem is over for at least 25 years!

So the advice is to think about what any lining might do the internal surface of the chimney and also to remember to ask for a 904 rather than a 316 liner.

New eco-products give hope!

The Dutch Postcode Lottery and Cradle to Cradle competitions have had some amazing finalists this year.

The winner this year's Postcode Lottery Green Challenge was BioMason’s CO₂-free brick production process, which uses bacteria to ‘grow’ bricks! Can't wait to see these around, especially given the amount of embodied energy in a conventional brick.

The other finalists in the American Cradle to Cradle competition include:

• Mushroom^R Insulation – a green replacement for plastic foams, which combines agricultural byproducts with fungal mycelium to ‘grow’ structural rigid insulation
• Bellwether Materials’ Softbatts – sheep’s wool insulation
• GR Green Building Products’ Green Cedar^TM and Green Slate^TM – synthetic roofing and cladding materials made from waste limestone and recycled plastic milk bottles and shopping bags
• Dutch Design Initiative’s reinforced wood wool cement board (pdf link)
• Ecococon’s straw panels
• Haplobuilt’s Haploblocks – a small scale prefabricated building system (pdf link)
• Ecor^R Universal Construction Panels made using waste cellulose fibre.

Great to see such a wide range of ideas being brought forward to help reduce our embodied energy associated with new builds, extensions and also some refurbishment.

Hot loft conversion this summer?

When we think about insulating our lofts we only think about keeping them warm in the winter. However, with summers projected to get warmer, we also need to start thinking about keeping them cooler in the summer.

So insulation works both ways, yes?

Well yes and no. Never easy is it!?

In the same way that solid walls help to reduce overheating by absorbing heat during the day, similarly higher thermal mass insulations are better at keeping peak heat down in spaces like lofts. So effectively if you have a choice between two different insulation materials that have the same final insulation values (for winter heat retention) then the one with the great mass will be better at reducing summer heat and keeping a more constant temperature in the room.

This means that one might be comparing a modern phenolic board (which will be more efficient per cm depth) and a deeper natural insulation. The obvious comparison is between these modern boards and a more natural wood fibre board.

Wood fibre has a higher decrement value (how much it slows peak heat). So each 1 cm of wood fibre will delay peak heat by 1 hour. So during the longer summer days, even a 6-10cm board will remove the peak heat of the day from your loft space.

To illustrate this decrement effect a study from Delft University of Technology in the Netherlands examined two similar houses, each with a roof U-value of 0.21W/m2K – one insulated with lightweight fibreglass and the other with denser cellulose. Both were oriented to the south and remained unheated during the study period, throughout which outdoor temperatures fluctuated by 25C. While the temperature in the fibreglass-insulated house varied by 13C, it fluctuated by just 3C in the cellulose-insulated house. When the temperature outside dropped to 10C, the inside of the fiberglass-insulated house measured 14C, yet it was 18C inside the cellulose-insulated house.

This flattening out of temperature fluctuations in a great advantage in their areas of houses that are most prone to high temperature variations. Worth thinking a bit differently then!

Last note, if you are concerned about head-height, you are correct, it might not be the best sole solution, but using an amount of higher density insulation would still be advisable. 

If you are able to lift the roof level, then using wood fibre sarking boards can be a great way of getting the same effect.

An old bay exposed

The render under the window was harder to get off. Attached to cement blocks that we used to fill gap when bay removed

The front of my house is flat with one large window downstairs. I sort of knew that it was likely that originally there was a bay there given that they exist on other houses in the street. However, it was only when I removed the render from the front (in my bid to stop the rising damp issue) that I confirmed its past existence.

The whole system is a bit of a mess, surprise surprise! The old foundations for the bay were still there, but there were no new real foundations for the new wall. The new cavity wall has been made from a concrete blocks and rendered. A vent was also installed to keep the structure drier (and of course colder!)

To deal with the issue I have, to date, removed the top layer of render and re-applied a lime render. This was mixed with a little cement to help with curing times. I have also installed a render drip to keep the water a little away from the 'foundations'.

The finish has been matched to the treatment used on the rest of the wall (stone), so this is a lime wash finish.

Next job is to remove more of the current 'foundations' and then re-build them with a little more structural integrity.

Ideally I shall re-instate the bay as it would add some character to the front of the house, create a nice seating area next to the window and also allow us to make a more thermally efficient structure. But this might be a longer term 'aspiration'!

Flat roof under pitched roof - An insulation tale

Several years ago, we had an extension put onto the back of the house, over an old flat roof. However the extension didn't cover the whole of the flat roof, so we had a pitched roof put over the remainder so that it gave a more reliable rain shield.

The builders insulated the new roof, but of course they didn't remove the old flat roof first! The insulation was just piled up over the old felt and left. The room underneath this is the bathroom and I had been wondering why it was still quite cold. Lots of insulation in the roof, so should be warm etc. So I had a look. It was then that I discovered what had happened.

So effectively what I had was a vented flat roof with a load of insulation above it. This meant that the wind was venting the old flat roof still and so I was only really benefiting from the amount of insulation that was in the flat roof structure!

So one of my jobs has been to remove the insulation, then remove the flat roof, inspect the insulation in the old structure (I wasn't expecting much!) and then do some remedial works. Fun, especially since the new roof only gave me around 1.2 metres of headroom at the apex. Being a 1.9m tall person, I was expecting a bit of a squeeze. I wasn't disappointed!

So I set about cutting out the old roof with my reciprocating saw and drill. What a lovely job. I had to cut out large rectangles of felt and chipboard to expose what lay beneath. I did this as close to the edge as height would allow to ensure that the final solution would be accessible as possible.  Anyway, as expected I uncovered a right old mixed bag. Some spaces between the joists had 5cm of insulation, some a collapsed 10. Some, none at all. No wonder is wasn't too warm in there.

The solution needed to be thought through, but was in the end, basic. The warm moist air from the bathroom will primarily vent through the extractor, but will also partially vent through the ceiling and insulation (just like in a standard loft). The insulation therefore had to allow this into the main pitched roof space and so I also needed to keep the eaves clear to give the required draught in the void (this avoids the risk of any condensation forming on the now cold underside of the pitched roof). So effectively I just piled up the insulation, that I had removed prior to starting, on top of the exposed ceiling boards to a depth of around 30-40cm and kept the required 5cm gap at the eaves for the ventilation.

Not so worried about autumn and winter's imminent arrival now, though will keep a check on the moisture issue since the insulation that I re-instated is recycled plastic rather than my preferred warmcel insulation. I would have preferred the recycled paper since it is breathable and hence any excessive moisture would be more easily transmitted through it than the plastic. Still another job done.

Cracks removed and new unconventional render applied

When doing my holiday work, one of the objectives was to remove the micro-cracks in the cement render on the house. These hairline cracks are terrible for letting rainwater in and then trapping it in the structure. Hairline cracks are really important to remove, especially on walls facing the prevailing winds (as the wind drives the water into the cracks) and also where any excess water is running down the face of the wall.

Oddly enough large cracks are less troublesome most of the time as any water can also evaporate off as well as seep in, however with the hairline cracks the evaporation is effectively eliminated.

Given that I wasn't prepared to remove all the 1970's applied cement render I merely wished to remove the cracks by widening them and then re-rendering using a breathable render. So I cut away the existing render using a disc cutter, then hacked off the render either using a bolster or the breaker that I had hired.

Of course what I exposed was more problematic than originally thought. The cracks were being caused by two factors. Firstly I found that the roof lead was channeling some rain water behind the guttering and into the wall, so I repaired this. Secondly, the wall underneath was not tied in very well (it was an extension at some time) and that past work had used a galvanised mesh to tie the render together. The mesh had of course rusted and hence helped to cause the crack.

I used a mix of hydraulic lime, sand and a splash of cement to do the repairs and to fix in the lime resistant mesh. The following day I mixed up the amazing Insoplast Insulating Plaster to render the repair. This will be treated with a breathable silicate primer and paint at the weekend.

The reason for using the Insoplast was not driven by primarily by its insulating properties (although these are a real bonus), but due to the fact that it doesn't require a wet substrate. It is put directly onto a 'dry' surface. This meant that I didn't have to introduce any moisture into the wall.

You can see from the above that I did two cracks in the wall. I also ended up doing the lower level of the wall. This was because I found that the lower render was very loose, and although not blown in the classic sense, it certainly had lost any real effectiveness. I again used the Insoplast plaster here and a stainless steel drip bead. Galvanised drips will slowly rust and blow the plaster, so even though the stainless was more expensive, it will save money in the long term.

Fingers crossed this work will help to keep the wall dry, a little bit warmer along its base and be flexible enough to stop any more cracks occuring.

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.