You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
We live in a 1920s semi detatched - the front and side facades are constructed from gritstone blocks, a 75mm(ish) cavity and then a single thickness brick inner wall.
Due to the nature of the ties, we can't insulate the cavity (would leave voids)
Both the bathroom and the kitchen have long external walls on the side facade that get very wet with condensation in winter (also the steamiest spaces, natch). Both walls feel noticeably cold to the touch. Neither room gets particularly well heated (which isn't going to change!), both have extractor fans (bathroom is triggered by the lights, so on when its in use; kitchen is the cooker hood, so use is much less)
We're due to redecorate both in the near future, and I'm contemplating the merits of stripping the walls back to the brick and installing insulated plaster board to try and reduce the condensation/thermal losses. The bathroom, we could go fairly thick, however the kitchen, due to door placements, we could only maybe go 50mm thick from the brick, inc the plasterboard.
A) is it worth it?
B) Will we cause problems elsewhere - eg by moving the dewpoint to in the cavity and rotting the ties? (not something I know a lot about)
Thanks!
As for A I'd say its well worth it. I just put the insulated board over the old plaster rather than stripping back to brick, but its made a huge difference to the room. It has two exterior walls but I only did the big one. That wall used to be ice cold to the touch and now it feels warm. The room isn't as cold in the mornings (we don't have the heating on at night). Very happy. That was about 8 years ago and the house hasn't fallen down. You will move the dew point but I wouldn't be too worried.
I was limited on available thickness for part of our bathroom, and even using 27mm insulated plasterboard it made a huge difference. Just be careful with cutting/fixing, etc. to avoid cold bridging wherever possible. Also have a think about the floor, even if it's just a 10mm insulation board under the tiles (or whatever your flooring of choice is).
EDIT: In terms of dew point, etc. if you're using an insulated plasterboard or similar and install neatly then moisture shouldn't be going past this. Plus, as it's warmer, your air extraction will take more moisture out anyway so should be a dryer space. Also, if the cavity is ventilated (hopefully!) then it'll do its job and dry out.
Rembrandt to do window reveals as well.
Rembrandt to do window reveals as well.
Must have a hell of a refurb budget for that 😉
We have a similar issue at our house, 1925 semi, no cavity or minimal at best. We had thick black mould in the kitchen mainly but putting anything near an external wall was a big no no, even with ventilation it still happens.
Were five rooms in and the difference is incredible even with about 22mm insulation, make sure you do any rakes as well as our bathroom guy didn't and guess where we get the mould problem now....
Fairly expensive, its messy but worth it.
Save some money and remove the old plaster yourself, if its in bad shape its worth taking off anyway. It does give you that extra bit of room if your in a fix for space in places like a kitchen or small bathroom.
Blimey - a forum consensus! Whatever next...
Rembrandt to do window reveals as well.
Assuming that's "remember" rather than getting a Dutch painter in, what exactly should I remember? There's 2 relevant windows in the bathroom - one is a sash, so has no reveal (although adding the insulation would create a narrow one), the other does have a reveal, but there's not much space to be adding more layers in there.
Thanks
We’ve had 2 rooms done with internal insulation in our 1885 Victorian detached. Done when the rooms were redecorated. Just insulated plasterboard. Difference is noticeable. better in terms of heat retention & feeling warm, drier, and of course great surfaces for subsequent redecoration.
Over time we expect to do other rooms in the same way.
As above, 1910s terrace with double and single brick external walls with no cavity. Cold damp and mouldy and never stayed warm. Removed all the old crumbly plaster then boarded with 50mm Kings pan. Difference was immense, marginal loss of space but warm and dry. Used the insulated plasterboard upstairs but the Kings pan was much better.
am contemplating doing this (if we ever exchange and complete) on a 1950’s flat, it has cavity walls but the main lounge wall is single brick solid with tile facings and a 5m long critall window so the U value of that wall is terrible, hoping that new aluminium (if we get permission) and 40mm of insulated board will at least make that wall as good as the other cavity walls, the decision i have to make is do we do all the other walls? the quote for that will help us decide as the refurb fund isn’t infinite.
what i’m not sure about is do you make it breathable or do you seal it all off so the air gap cannot get condensation inside? (dot and dab)
i guess if you are doing an old solid wall it’s different to what you do with brick/block cavity?
we can’t insulate the cavity as the insulation will just fall down and fill up the ground floor!? so unless everyone can agree to having it done it’s never going to happen which is annoying as it’s probably the most effective and cheapest way to lower the U value.
We did it in the bathroom on our last house (1900s terrace), 50 mm insulated plasterboard. Went from cold and grim to warm and not shivering while shaving in winter.
You more or less dry line the room with the insulated plasterboard rather than the foil backed dry lining board. The Kingspan and Celotex websites have a fairly good explanation of the different layup options. Other brands of phenolic board are now available. Just check the insulation value. Rockwool and white polystyrene need about double the thickness for the same amount or insulation.
Its Wedi board for bathrooms if you are going to tile.
insulated and waterproof.
The insulation manufacturer should be able to do a calc to see if interstitial condensation is likely be a problem.