Internal Insulation for solid walls - a mini blog

RenovationMan

whasup wrote: »

That's fine. It's for you to make your mind up. I speak from a great deal of (professional) experience in renovating and refurbishing period properties. Sadly, many of the people I meet in my professional capacity have learned most of what they know from books. I learned mine from hands on research and years of taking buildings apart and undoing the mistakes of 20, 30, 40 years ago - the cement years.

Don't get me started on cement. The person who originally renovated our house used cement everywhere and I'm slowly and painfully removing it. At the minute we're removing cement pointing from the interior walls - luckily about 60% of the walls were plasterboarded so the original lime pointing remains underneath, but the rest were left bare as 'feature walls' and awful thick grey cement pointing was used. I'm using a lime putty mix to replace the cement and it looks so much better as well as being far better for the walls. It almost seems a shame to cover the walls up because they look so nice, but we're loosing too much heat through them.

Once the weather picks up I'll be able to get outside and make a start on the external pointing, but it'll take me years to all the cement out of the house.

bobhawke

RenovationMan wrote: »

There has been a huge amount of discussion around putting insulation into older houses that have solid walls and I've read articles that champion both sides of the debate and I have personally come to the conclusion that Breathable is the way to go for our home. Naturally, everyone should DYOR and come to their own conclusions.

I saw several articles that stated how difficult it was to prevent internal water moisture (condensation) going through the insulation and condensing on the cold walls behind, causing damp and the resultant mould growth and damage to stonework and especially beams/floor joints. The articles all stated that even with the vapour barriers on the back of celotex or Kingspan (the silvery material), taping the joints between abutted celotex boards and even adding a separate vapour control layer, moisture can get through over time as the seals deteriorate). Contrasted with this is breathable insulation that stops damp from being trapped behind the insulation (the insulation forms part of the wall) and allows any moisture in the walls to vent back into the room.

The information that really got me on board with breathable insulation was in "The Old House Handbook", which described how rising damp was caused in old houses by the application of a damp proof membrane and concrete slab into the ground floor, forcing ground moisture along the underside of the impermeable sheet and up into the walls.

It's a brilliant book and I highly recommend it to anyone who has an older house.

I will buy that book and have a read. I have damp problems in my house, ground floor flat. Doesn't help that neighbours have flooded the place a few times in last 10 years.

RenovationMan

Well, time for a mini update...



I've chiselled out all of the cement pointing:


and re-pointed with lime mortar:



and so I'm now in the postition to start levelling the wall with lime hemp plaster, which I'll be cracking on with over this weekend.

jamesingram

Some interesting discussion here on similiar topic that may be of interest to you Ren.man http://www.greenbuildingforum.co.uk/forum114/

RenovationMan

I spent part of the weekend 'dubbing out' the hollows in the stone wall with lime hemp plaster. The plaster was pre-mixed and came in plastic bags, which I just knocked up before use. The hemp and lime mix is an interesting product and it was a bit like smearing horse manure on the wall, though without the smell.

As well as dubbing out the hollows I plastered a small section in the corner of the room as an experiment. I've scored the surface for the next layer and I'm just leaving it to dry out to see how it gets on.

After a day the plaster is a bit dryer and feels like wheatabix rather than horsemanure. I'm a bit dubious about it to be truthful but I'll hold off commenting until it hardens completely.

RenovationMan

My dubbing is now finally dry (it takes forever with lime products) and so I spent the whole day yesterday putting on the top coat of hemp lime plaster. I've got another day of it today and it should be finished.

At the moment the lime is a sandy colour, but when it dries it turns white. It's nice to have put a bit of insulation onto the wall already with the hemp, albeit not very much (even in the areas where I have dubbed out and the plaster is 4" thick)! It's a start though and once this is dried I'll have a flat and level surface to attach the breatheable insulation to.

RenovationMan

I haven't updated the blog for a while as I've been busy at work and doing DIY!

I have completed covering the external wall with the lime/hemp plaster and it's now hardened and is ready for the breathable insulation. I'm still pondering whether to keep the stone window reveals or to cover them with insulation/plaster with 'bullnosed' corners (curved).

RenovationMan

I have almost completed the acoustic/thermal barrier on the connecting wall. I just need to batten the final section once I have completed the breathable insulation. The acoustic insulation is 30mm rockwool slabs which add a good thermal element but is great acoustically. This is important because on the other side of the wall is a livingroom and so we don't want late night TV watching in one room to encroach on bedtime in another.



At the same time I'm taking the opportunity to change the electical wiring from the old colours to new and to fit fire rated LED spotlights in the room. The next job I'll be doing is to fit acoustic insulation into the ceiling with acoustic firehoods over the spotlights.

RenovationMan

I'm just having a bit of a break after finding a big hole in the corner of the room behind the floor joist and just above where the boiler flu goes out of the wall (the bedroom is above the utility room). To be fair to the plumber, he did say that he was no builder and just stuffed the hole with rock wool once he had finished. I just didn't realise how large the hole was, or how deep it was!

After sticking my head down betweeen the joists and looking into the hole I could see that the backside of the external facing stone, plus a lot of light creeping through the gaps in the mortar. So much for energy efficiency and draft reduction.

I've just spend about 2 hours shaping blocks of sandstone that I have in what I call 'our reclamation yard' and what my missus calls 'the eyesore behind the garage'. I pointed the interior of the exterior stone to stop the light (and drafts) coming through and then bricked up the opening, filling the gap between the internal and external courses with the bits of rubble from the shaped sandstone and a lot of dried lime/hemp plaster I had knocking about.

I fitted the stones and pointed them with lime putty and once that's dry I'll render over the top with hemplime plaster. All of this should help significantly with our drive to reduce our heat loss, heating bills and carbon footprint.

SteveH2

Hi - I just came across this thread and can see you are likely very busy but am facing a similar scenario and would love an update on this project if you have the time (or indeed see this post).
Best wishes