Cavity Wall Insulation for a Victorian Semi?

My house is a semi built in 1873, from Yorkshire stone.
It is a devil of a job heating it and keeping the heat in.
I'm getting the existing poor quality double glazing replaced next summer, but I am also considering cavity wall insulation.
I'm not sure how effective CWI is in house such as mine, and also the effect it has on resisting or promoting damp penetration.
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On 05/10/2010 21:19, S R wrote:

No reason for it to not be effective, assuming you have a cavity to insulate! Many properties of that age will have a solid wall construction.
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Cheers,

John.

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On 05/10/2010 21:19, S R wrote:

If your walls are two feet thick then they are almost certainly rubble filled. Such walls have voids but AIUI cavity wall insulation is not effective. Two feet of wall is a better insulator than 9 inches of wall but it is not comparable with a modern insulated wall.
If the wall is substantially thinner you will need to establish what there is between the inner and outer courses. 1873 is early for proper cavity walls in brick built houses. I would have thought a cavity would be unlikely in a stone built house of that age but I could be wrong.
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We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Roger Chapman
Not by much, it isn't. Once the heat starts travelling through it, it just keeps going. A 2' stone wall is nearly as bad as a single skin of brick.
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On Tue, 05 Oct 2010 21:19:12 +0100, S R wrote:

Get in touch with the local council environment dept. who will come round to check whether you are eligible for a grant. Mine has solid (brick) walls at the front and cavity at the back, but they drilled the wall and found that the gap is too narrow. :o(
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Jim S
Tyneside UK
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In what way is it poor quality?
I ask because as long as it is a) not rotten b) seals work c) no howling gales through it d) windows not broken or steamed-up (which can be fixed) then windows are windows and the money may be better spent elsewhere...

... such as after finding out you do not have a usable cavity wall (sufficient depth, free from obstructions etc) that you could insulate on the inside via sticking insulation on the walls or building a free- standing timber frame inside into which you stuff insulation and dryline (plasterboard).
The reason I say that is double glazing is quite expensive (payback period is 50-100yrs over single glazing and even longer if you already have double glazing), and insulating solid walls on the inside is also rather expensive. If you DIY it will still be costly re materials, redecorating etc - but the difference is you reduce your heating bill really quite significantly. If you are spending 800/yr on heating- alone now, it is quite conceivable you could reduce that to 300 as well as feeling somewhat warmer. Payback period would be quite long even though.
You can insulate on the outside, but unless that is rendered it can significantly change the character and may be prohibited if a Gr-II listed building etc. If possible, however, you can the thermal mass of the inside as long as you can stuff enough heat into it in the first place. You would use polystyrene stuck to the wall with plastic pegs, with an expanding mesh, and a render coat over the top - or something along those lines.
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replacing dg is unlikely to yield any useful result unless its so broken its howling.

You need to find out what construction your walls are. Dont assume theyre all the same, old houses can have several different wall types. Measure the wall thickness, and drill a little test hole to see if there's a cavity in there, and if so of what depth. Also let us know fi the stone's rough rubble or sawn blocks.
If there's no cavity there are other options.
NT
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S R wrote:

There are a number of factors here, the first one being you can't have CWI if the back of the stone is undressed - if the stone is not uniform at the cavity side, it creates voids and this is where damp gets in - CWI cannot cause or perpetuate damp unless it's not completely filled. No reputable company would touch it with a bargepole if the stone's undressed.
Second is cavity width - it needs to be a minimum of 50mm all over for it to be effective, any less and it's highly unlikely anyone would take on the job.
If the stone is dressed *and* you have a wide enough cavity, then yes, it will create a more comfortable home - the heat stays in longer, meaning the boiler has less work to do, plus it takes less heat and energy in warming up in the first place, with the added bonus of it working in both directions - it keeps the house cooler in summer too.
--
Phil L
RSRL Tipster Of The Year 2008
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