Internal Insulation for solid walls - a mini blog

Fred_Bear_2

RenovationMan wrote: »

We're not allowed to insulate externally as the building is listed and we live in a conservation area. We are therefore forced to use internal insulation, which is a shame because we then face the problems of moisture in the walls and we lose the thermal mass of the sandstone.

To fix the first problem I have been looking at breathable insulation that will allow any moisture in the walls to pass through the insulation and into the house, to then be extracted via a Heat Recovery Ventilation system (TBA). After researching and subsequently discarding many products such as sheeps wool, hemp batts, etc. due to the thickness required to hit current building regulations, the expense and the hassle involved in their installation, we have found a breathable PUR board similar to celotex/kingspan boards but with evenly distributed holes filled with a vapour permable mineral.

The boards are called IQ Therm and manufactured by a German company called Remmers. The boards we will use are 80mm thick with a thermal conductivity of 0.031 W/mK. The boards are installed and then covered with the manufacturer's breathable render and painted with breathable paint. The render will have the same suface quality as the existing internal plasterwork and the manufacturer's breathable paint can be used on the IQ-Therm product, lime mortar and gypsum which means that we won't have to touch any of the internal dividing walls other than to give them a bit of a skim and paint them.

Hi Renovation Man,
I have exactly the same situation as you (apart from having 225mm solid brick walls). I took advice from 5 architects and energy experts at the National Self Build & Renovation Centre in Swindon and received 5 different opinions, some totally opposite re breathable/not breathable. After my own research I decided, despite the high cost, to use the Remmers product which combined high insulation values without excessive thickness. But I eventually decided against this when I learnt that nothing can be fixed to the wall afterwards. As the insulation will hopefully be in place for decades, this seems a severe limitation to me.
Fred

Fred_Bear_2

I hadn't noticed that this thread was so old and that Renovation Man disappeared long ago. I hope he was successful.

EricMears

His last posting was 'only' 18 months ago. Plenty of people go that long without posting although (alas) we don't seem to have many like that in this section

ed110220

I'm not sure if it is helpful to your project, but I've done DIY internal insulation of system-built walls (1940s British Iron and Steel Federation construction), which are often grouped with solid walls.

The main difference was that in my case the insulation could be put into the existing thickness of the wall rather than losing roomspace.

What I did was to strip out the original wall lining and studwork, install 70mm Kingspan/Celotex foil-backed insulation board, leaving a 50mm gap behind for ventilation, then build up the new studwork in front of it infilled with 50mm Kingspan/Celotex between the studwork, then plasterboard and skimmed over.

You can see about it here: Internal Insulation Project of BISF Bedroom by Ed

Kernel_Sanders

EricMears wrote: »

His last posting was 'only' 18 months ago. Plenty of people go that long without posting although (alas) we don't seem to have many like that in this section

So Eric, which contributors here would you prefer not posting for 18 months?

EricMears

Kernel_Sanders wrote: »

So Eric, which contributors here would you prefer not posting for 18 months?

Don't worry - you're not one of them.

MFW_ASAP

Hi Guys, I am still here (RenovationMan) just under another username. I had other stuff to do on the house and as that room was a 'spare' and so free from hassles by the missus, I left it for a long while. I'm back doing it now and so will provide an update.

As you can see from the earlier pictures, I had battened out one of the internal walls and filled them with acoustic insulation. I had also filled the ceiling void with acoustic/thermal insulation. I've now covered both with woodwool boards that are great for carrying a lime plaster and also have an element of thermal and acoustic insulation. The LED spotlights are also fitted and are very bright, considering they all amount to 30 watts (6x 5w GU12 LED bulbs).

I decided against using the remmers product and instead removed all of the plasterboard in the room and replaced it with insulated woodwool and also fitted a 100mm woodfibre board to the inside of the external wall. The walls and ceiling are now ready for lime plastering, but first I need to fit the flooring. I'm pondering fitting underfloor heating in the house and would be interested in any views from members here on the energy efficiency pros and cons of UFH vs Radiators.

I'll take some more pics of the room to show progress this weekend (providing I can remember the photobucket password!)

As an aside, the room has no heating except for what rises from the floor below and it is significantly warmer than the other rooms in the house due to all that insulation.

MFW_ASAP

Looking back at the start date of this thread, it's shocking that I still haven't finished this room! I really need to get cracking as it'll be 2 years in next month!!

In my defence, it did take ages to strip off all of the 'dot and dab' plasterboard and fit the woodwool and as I work away from home all week, I only have the weekends (and often I prefer to spend the time with the family).

Excuses, excuses!

colinm

I just wanted to add my experience with solid wall insulation.
I live in a 19th century cottage, built of god knows what - stone, brick, clay...probably anything they could lay their hands on! Fortunately not listed or in a conservation area, so I wasn't restricted with planning (although did get written permission from local authority before I started work).

I considered internal insulation, but also suffer from rising damp. For this reason, and the upheaval, I decided on external insulation. The exterior of the house was also a bit of a mess and needed attention.

I went through the Green Deal to get it done, and contacted a local supplier to do the EPC and quote for the job. I went with them, and although it did take about 6 months from start to finish, I am over the moon...the insulation looks amazing, the job was done very professionally, over half the cost was subsidised and I got £650 cashback. I decided to pay up front rather than use Green Deal finance, which was not only an expensive loan, but also a horrendous mess.

Most importantly, the house feels noticeably warmer. My boiler is on less, and although we have had a mild winter, I normally get through on average 250 litres of oil per month during the quarter period Nov-Mar. To date I reckon I've used about 300 litres in total during the same period. With oil at about 65p/litre I estimate that I've saved around £455. I paid about £2500 for the insulation after cashback, so I'll have a return after 5 years. (I have rounded here a bit, so not precise numbers).

So in summary, no regrets...the house looks better, no mould in any rooms from condensation on the cold walls, and my heating bill has reduced dramatically. Hope this helps anyone considering wall insulation.

SRB

Who did you use for your external wall insulation, colinm, and how did you get it subsidised? Sounds like it's what I should be looking towards (solid walls in Suffolk)