Cavity wall mainly, you may/may not have read/noticed my eco heating thread, now insulation! making said house as well insulated as possible is obviously an objective too.

now we’ve had had some initial feedback from the full structural survey (full report due next week) and there were a few comments about damp and wall ties. The house is 1920’s so has old style fairly porous bricks and mortar.

I’ve looked around and read about rising damp actually being pretty rare and it’s more often than not something else and damp proof injection being a pointless waste of money and voodoo. I’ve also read about Cavity wall insulation and bridging issues and that some are worse than others for it depending on construction type.

Now I want to insulate (without internal studding robbing space due to the house not being that big) but I’m wary about damp and wall ties issues.

I’ve heard horror stories, calls of scaremongering and talk that some are better/worse than others for this and that, but no specifics (that I’ve found anyway)

anybody have any real work experiences with this sort of thing?

Consider external wall insulation and re rendering if the outer skin is potentially porous

sorry should have said, the house is in a National park with strict planning. Rendering the house and changing the external appearance of the house is very unlikely to be an option.

modern levels of heating + old cold walls = damp.

warm air with humans in, and all of their pesky breathing, cooking, and drying clothes on radiators, carries a lot of moisture.

where this warm humid air meets a cold surface (your old cold walls), you will get condensation.

this problem is made worse if you’ve got modern non-breathable plaster and or paint.

if you have cavity walls, insulation will help with the damp (the internal side of the wall will be less cold – so produce less condensation).

but, your 1920’s house might be a bit early, you may not HAVE cavity walls…

(there are a lot of us facing this very same problem; how to insulate an old house)

I looked into this several times and came to the conclusion that the risk of getting a big damp problem outweighs the benefits of saving energy. Apparently the worst situation is an exposed location with a wall facing the direction of prevailing winds and rain which is our exact situation so I decided not to risk it.

The house does have cavity walls, I’m no builder or structural surveyor or anything, but I can spot a cavity wall. It’s a very similar construction to my current place built in 1910.

I want to insulate for obvious reasons BUT! I don’t want to cause myself even more problems by doing it

hmmm confused!?!??

but, your 1920’s house might be a bit early, you may not HAVE cavity walls…

Ours is turn of the century and has cavities. I know that with 100% certainty.

I’m not really sure on this one but you have an external wall that is suffering from condensation and damp because of a lack of insulation AND cold bridging. Wouldn’t the cavity wall insulation having an effect on the general condensation but without any change to the cold bridging problem be an improvement?
I’m sure you read plenty, but here’s some more.
The argument is relatively simple in that anyone with an interest in one product is going to issue scare stories about the competition.

My girlfriend flat and my sisters house have both been affected by damp recently, in both cases this was caused by bridging between the outer wall and the lathe and plaster inside the flat/house.

Basically as the properties have been modernised over the years (double glazing fitted, central heating installed and the likes) bits of plaster and rubble had fallen down and built up in places between the outer wall in inner plaster.

After seeing how little material was required to generate damp patches i wouldn’t be considering anything that was going to fill that air gap.

If the insulation of a specific area was causing a problem then the only thing i have seen that I would consider would be the foil, plastic bubble wrap type stuff but to install that properly you would essential need to rip out all the current plaster then install it across the uprights and plasterboard over the top. The combined thickness would be about the same as lathe and plaster and it also acts as a barrier between the outside wall and plaster to prevent future bridging. The obvious problem with this is the expense and whether you are likely to recoup the outlay in reduced heating or feel a major benefit within the property.

Ours is turn of the century and has cavities. I know that with 100% certainty.

Our 1910 house definitely doesn’t have cavity walls so age can’t reliably act as a guide to whether they are cavity walls.
What does your surveyor recommend as far as remedying the damp problem goes? He should be able to suggest a way forward and give you some idea of the cost.
Most damp is condensation (especially if it comes with black mould) or penetrating damp rather than rising damp.

Our 1910 house definitely doesn’t have cavity walls so age can’t reliably act as a guide to whether they are cavity walls.

Pass.

But I know mine does because I have fed an extractor fan exhaust through the small gap (they aren’t full size cavities) and I ended up with hands that looked like they had been mauled by a bobcat.

We’ll get the full details next week. I think the damp probably isn’t that serious and can be resolved. the place has been empty for a few months so that’s probably not helped.

what I’m after more than anything is advice/pointers on cavity wall insulation in older houses which have more porous materials than modern houses and have a greater potential for damp issues, old slate DPC is never going to be good a as a modern unbroken plastic DPC etc….

now I’ve heard roc wool is bad for bridging
but then there’s foam, polystyrene balls + ??

Just had people around looking at our house and insualting the cavity. They want to use an insulation that contains silicone and therefre doesn’t track water back to the internal leaf – quite how true this is I haven’t looked into it yet.

Rising damp is a bit of an excuse passed off by many people in the past but most of the time is a crap dew point in the build, por ventilation or crap detailing during construction phase ie window reveals

I’m sure the current “damp” is nothing to really worry about and can be sorted.

any idea what it’s called Taff?

just did a quick Google and could find anything similar other than sheet stuff which needs installing at build time

Same situation here, bought a? circa 1920’s house. Ordering a survey this afternoon, but it needs a CH system. Going for 270mm in the roof no problem, has Double glazing. If it does have a cavity I’m still out on that decision. Will ask a few trusted friends.

Found this (though scotland)

http://www.energysavingtrust.org.uk/Home-improvements-and-products/Home-insulation-glazing

I had silicone coated rockwall blown into the cavity in my place. No moisture tracking that I’ve noticed so far (well, no damp walls or mould) after a couple of years.

We do get condensation upstairs on the bottom inch or so of the windows (they are double glazed), but only in the room we are sleeping in. The walls themselves are now much warmer to the touch so I don’t think any moisture would condense on them.

We keep a couple of upstairs windows on the locked but open a-jar to help ventilation and any inside drying washing is in a room with a de-humidifier to minimise the moisture in the air.

Just found this an interesting read, a good few comments about windows and VDPC which is pretty interesting.

cheers catnash I’ll have a look at that in a mo

[Edit] oh and they seem to recommend poly balls too
lots of talk about shoddy installs with loads of gaps which cause a lot of problems not the insulation itself

Fundamentally, I’d just not have anything in a cavity … i cant see past how you wouldn’t get some sort of capillary effect with any substance, be it some fancy material which claims not to track damp or otherwise.

How thick is the surface on your walls at the moment? If you were to remove it back to the brick, how much space would you gain, and how thick would your new stud be? Its not necessairly going to make a massive indent into the rooms … things like kingspan between the studs would better than nothing.

Hmmmm, can’t decide on cavity wall insulation either.

There seems to be lots of for/against arguments and a lot of ‘against’ arguments can perhaps be attributed to insulation put into a house that it wasn’t suitable for, vent bricks being blocked up, general poor install of insulation.

I think for the moment I am going to stick more insulation in the loft. It’s pretty spartan at the moment. We have a shallow pitched roof, so I am going to double up the insulation at the edges as it is largely unusable space that isn’t currently boarded up.
The rest of the loft space is boarded up, but I am not sure we need all that storage space, so will probably take up 1/2 the boarding & add to the insulation there. If the insulation looks ropy underneath the boards, I will replace the insulation or top-up under the boards that I am keeping in place.

I’ll definitely do loads in the loft for sure
probably under floor boards too
walls still?????

where’s the best place to get it from to take advantage of any/all subsidies? I assume not B&Q

I’m happy to fit it myself

just checked B&Q actually sell subsidised rolls ready to go at the same price and the ones via the energy company’s 8)

^^^^ yeah, B&Q rolls are very cheap. I might have to drag my OH’s dad along to get the rolls in the back of his Doblo…..