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Cold outside walls
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sean
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 42219
Location: North Devon

Posted: Fri Mar 11, 05 2:21 pm Post subject:
Screwfix do various types of insulating 'stuff', they might be worth a look.

judith

Joined: 16 Dec 2004
Posts: 22789
Location: Montgomeryshire

Posted: Fri Mar 11, 05 2:36 pm Post subject:
Insulated plasterboard or Celotex will help, and won't take up as much room as a stud wall with insulation. Check the condition of the external pointing - you may be getting damp, and therefore cold, coming in through cracked/missing mortar. A large quilt / tapestry / curtain hung on the wall would help a bit.

moogie

Joined: 02 Feb 2005
Posts: 525
Location: Near Bridgend

Posted: Fri Mar 11, 05 4:01 pm Post subject:
Does any one know how long it takes damp treated walls to dry out once they have been injected/tanked? I had mine done about 14 months ago and they are three foot stone walls and they haven't dried out yet - are they meant to take that length of time or should I get the builder back in? Any suggestions?

tahir

Joined: 28 Oct 2004
Posts: 45670
Location: Essex

Posted: Fri Mar 11, 05 6:04 pm Post subject:
I've no experience but that sounds way too long, any ideas anyone?

Treacodactyl
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 25795
Location: Jumping on the bandwagon of opportunism

Posted: Fri Mar 11, 05 7:20 pm Post subject:

treehuggermum wrote:

Quote:

treehuggermum wrote:
Bad how?
Someone will always say something is bad for some reason. In the case of cavity walls, there are claims that is causes or makes problems with damp worse.

Oh I see, I still think it's a very good idea, not least because it apparently saves between �70-�100 a year in energy bills, so will pay for itself in 12 to 18 months.

[/quote]

Figures for energy saved are a little optimistic, IMHO. I think it would save 10% of the energy lost so it wouldn't save that much.

I've had it done but I have also noticed that when the holes are drilled in the outside wall the hammer action tends to break off brickwork that falls into the cavity and bridges the gap. This could then cause damp but may not be a high risk.

Wall ties should be at an angle or design that stops water passing the gap.

Gervase

Joined: 17 Nov 2004
Posts: 8655

Posted: Mon Mar 14, 05 2:57 pm Post subject:

moogie wrote:

Does any one know how long it takes damp treated walls to dry out once they have been injected/tanked? I had mine done about 14 months ago and they are three foot stone walls and they haven't dried out yet - are they meant to take that length of time or should I get the builder back in? Any suggestions?

If they're stone walls, make sure that whatever's on the outside is breathable and that the drainage is adequate.
Too often you'll find a modern impermeable cement render on a stone wall and, as you've got no effective damp-proof course or cavity (as you have with modern brick walls), they will wick moisture from the substrate and the only way it can escape is into your house. Modern materials and stone houses don't sit happily together if you have any risk of damp.
Consider using a breathable lime-based render instead, and think about having a french ditch running the length of the wall outside, set below the level of the interior floor - modern perforated drainage pipe is ideal - so that surface water gets taken away from it.
If it's been injected, though, I'm afraid you may have to live with it as the damage has been done - though you might consider taking action against the firm wot did it, as injection treatments for stone walls are not a good idea, and if they advised you otherwise they're cowboys!

judith

Joined: 16 Dec 2004
Posts: 22789
Location: Montgomeryshire

Posted: Mon Mar 14, 05 3:17 pm Post subject:

Moogie, I must say that I agree with Gervase - a standard injection treatment for stone walls sounds very odd indeed (we have an electro-osmotic system for our thick stone walls). And if they are tanked on the inside, you shouldn't be getting any damp inside at all, otherwise the tanking isn't doing its job properly. Exactly what did your builders do?

Assuming all is well, however, 14 months doesn't sound too long for the walls still to be drying out, although I would think you would notice the difference by now. Have you tried running a dehumidifier to speed up the process?

tahir

Joined: 28 Oct 2004
Posts: 45670
Location: Essex

Posted: Thu Mar 17, 05 12:57 pm Post subject:

Finally got something for you from a member of the AECB (Association for Environmentally Conscious Building):

Dan wrote:

That's a really good question, that is.

The best option is exterior cladding, because it maximises the thermal mass of the brickwork (ie. the bricks will absorb heat and gradually release it back into the house, maintaining an even temperature). Exterior cladding can be done with PIR foam boards such as Kingspan, which are then rendered over for weatherproofing. This is a good website for info on this:

https://www.theyellowhouse.org.uk/

The problems with this technique are that it can be difficult to get the detailing right around windows and doors; there isn't always room under the edge of the roof for the walls to gain thickness; and it's not always appropriate for old terraced or semi-detached houses.

Internal insulation can be easier, but involves a fair amount of upheaval. It's ideal to do if a house is being completley refurbished. Skirting and ceiling coving have to be altered or replaced, radiators may have to be moved, and there's not much point to interior wall insulation if you're not also going to lift the floorboards and insulate all the under-floor cavities, as if that's left undone, there's a cold-bridge formed by the void.

Again, PIR foam board can be used, then plasterboarded over - it's nasty stuff but it's effective. Plasterboard with a built in polystyrene backing (e.g. Gyproc Thermal Board Super) is probably the best option in terms of ease of application and price, and it comes in various thicknesses, but polystyrene is a very energy intensive material to produce, and won't biodegrade - same problems as PIR foam.

Another option is timber studwork with cellulose (recycled newspaper) insulation fitted into it, which can then be plasterboarded over. This is excellent in terms of embodied energy and toxicity, but the problems are that it takes a fair bit of work, needs a ventilated air-gap between it and the brickwork, and to be effective needs to be at least 100mm thick, which will take up too much space in a lot of houses.

One technique which I'm working on at the moment, and which I'm sure can be successfully used on interior brick walls, is a straw/lime/clay render, similar to the one Keith Hall describes applying to a straw bale house in his article in BFF 14, page 58.

This can be applied straight to bare brick, up to two inches thick, and is at once a plaster finish and an insulant. It's not possible to acheive a perfect flat finish as with traditional plastering, but it's fine provided you like the look of slightly wavy, lumpy, undulating walls. It would be very messy, fairly labour intensive to produce, and possibly quite time consuming in the application, but I still really like the idea.

I've seen it done in France, and I'm waiting for the exact recipe - I'll post details here once I've tried it.

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