Single skin brick wall - plastering solution recommendation

[larkim]

Old gas fire was condemned, so being middle class we of course opted to hav e a wood burning stove installed.

House is a 1905 single skin detached with suspended floor in the lounge, bu t installation was fine enough despite the old fire being off-centre in the existing fireplace, so the fitters needed to move everything to the left a bit.

On cutting out the new hole, what we thought was detached plaster underneat h the lining-paper covered wall, the fitters exposed what appears to be a c hipboard lining with apparently a tar used to adhere the chipboard to the w all. As he pointed out, not exactly the most fire-retardant covering to ha ve in a house...

So we will be having the whole wall stripped back and re-covered reasonably quickly in the new year. Not DIY, but wondering what input I should / cou ld have on the spec of what is put in place.

It?s a fairly significant wall which faces broadly ESE, running for about 8m on a long thin room. There is one wooden double glazed window on that wall, plus a radiator (and the fire place), the main window in the ro om though is single-glazed original glazing, and the floor is suspended wit h bare floorboards. It is the coldest room in the house (before the new fi re is working) and can get a bit of a draught going if the wind is in the ?wrong? direction.

Assuming we don?t really want to lose floor space (so I?m r uling out creating an air-gap with a batten frame etc), and at the moment a re constraining ourselves to thinking about only having that one wall re-do ne, what are the recommendations for materials assuming we get everything r emoved back to the brickwork? Are we likely to be creating ourselves some damp issues if we go for a top end insulating plasterboard etc?

Any pitfalls that I?m wilfully or unwittingly ignoring?

Thanks in advance for any tips!

Matt

[stuart noble]

ave a wood burning stove installed.

but installation was fine enough despite the old fire being off-centre in t he existing fireplace, so the fitters needed to move everything to the left a bit.

ath the lining-paper covered wall, the fitters exposed what appears to be a chipboard lining with apparently a tar used to adhere the chipboard to the wall. As he pointed out, not exactly the most fire-retardant covering to have in a house...

ly quickly in the new year. Not DIY, but wondering what input I should / c ould have on the spec of what is put in place.

or about 8m on a long thin room. There is one wooden double glazed window on that wall, plus a radiator (and the fire place), the main window in the room though is single-glazed original glazing, and the floor is suspended w ith bare floorboards. It is the coldest room in the house (before the new fire is working) and can get a bit of a draught going if the wind is in the ?wrong? direction.

ruling out creating an air-gap with a batten frame etc), and at the moment are constraining ourselves to thinking about only having that one wall re- done, what are the recommendations for materials assuming we get everything removed back to the brickwork? Are we likely to be creating ourselves som e damp issues if we go for a top end insulating plasterboard etc?

If you can get even an inch of celotex on the wall, it should make a huge d ifference to comfort levels.

[tabbypurr]

ly quickly in the new year. Not DIY, but wondering what input I should / c ould have on the spec of what is put in place.

ruling out creating an air-gap with a batten frame etc), and at the moment are constraining ourselves to thinking about only having that one wall re- done, what are the recommendations for materials assuming we get everything removed back to the brickwork? Are we likely to be creating ourselves som e damp issues if we go for a top end insulating plasterboard etc?

PIR is the answer. Celotex, Kingspan, etc. Insulating plaster is more money and less insulation - and IIRC may also be polystyrene foam, much more fla mmable than chipboard or anything on Grenfell.

Damp shouldn't be a problem if the insulation is on the interior and coated with ali foil on the warm interior side.

NT

[Iggy]

replying to larkim, Iggy wrote: All you need to know is that you're screwed. Either you stay with gas (the woodstove guys will understand) and throw-in a new stand-off liner or the chipboard has to come out (wherever it is) for the woodstove. A woodstove will require air-gapping and insulation from combustibles and require fireproof materials from start to finish in its chimney flue zone.

A gas fireplace is VERY different and very much your kitchen range, which may not have ANY exhaust or "chimney". If the woodstove's going to happen and there's no turning back, for some unreasonable reason. Then, things like Concrete, Fire-Brick and Refractory Mortar have to replace the tar and chipboard. The woodstove won't work out as planned, it can be returned and refunded.

[Andrew]

If the whole wall is covered with chipboard stuck on with bitumen then I guess this was done to deal with a problem of penetrating moisture through what is presumably a 9 inch solid wall. Leave it in place.

Removing all the decoration and overlaying with another layer of 'celotex'-type stuff works wonders.

Also consider stopping the wind-chill effect of a northerly wind on the exterior brick face with sonething like this

[Andrew]

PS. Don't bother with using this stuff on a cavity wall. It's only use is to reduce water penetration into the outside face of a solid wall which then suffers from the wicking effect of a cold wind.

Wilko sell a similar product made by IKO, but that is solvent- based and cheaper.

[larkim]

Woodstove is in and certified. Chipboard was pulled back to the required d istance from the fireplace chamber etc. so no issues there.

COnfirmed with them that all building regs are satisfied, and checked this out myself with ref to minimum distances etc.

So thankfully we?re not screwed. Gas had to come out as it was cond emned in any event.

All I?m interested at this point is what solution to use for the wh ole wall, now we?ve resolved one part of it.

[larkim]

We?ll gain some space with removing the chipboard lining. Wonderin g whether to go all the way back to the brickwork across the whole wall, if sections of it aren?t lined with the chipboard (not pulled it all back yet so not sure!)

[Iggy]

replying to larkim, Iggy wrote: Thank you that's very helpful, I'm glad the woodstove worked out so well. Frankly, I'd say leave it alone and just patch what was disrupted, since it hasn't been a problem yet and the interior facing of an exterior wall doesn't protect anyone, anything nor fix the rest of the room.

Although, if you're concerned, then Cement Backerboard (i.e. Hardie or Aquadry brands) with Insulation Board (i.e. Celotex or Jablite brands) behind would be your only best choice in addressing increased comfort, water vapor control and fire safety. Those would be mounted separately or together with Masonry Screws drilled into the brick's mortar joints.

[tabbypurr]

nably quickly in the new year. Not DIY, but wondering what input I should / could have on the spec of what is put in place.

?m ruling out creating an air-gap with a batten frame etc), and at the mo ment are constraining ourselves to thinking about only having that one wall re-done, what are the recommendations for materials assuming we get everyt hing removed back to the brickwork? Are we likely to be creating ourselves some damp issues if we go for a top end insulating plasterboard etc?

oney and less insulation - and IIRC may also be polystyrene foam, much more flammable than chipboard or anything on Grenfell.

ated with ali foil on the warm interior side.

That advice would leave an impermeable barrier on the cold side of the new insulation, a recipe for damp & mould. I would not do that.

NT

[Brian Gaff]

Why is one window single glazed. Seems a bit daft. I'm a bit confused as to why the whole wall needs to be redone. Could you not just remove the dodgy insulation close to where the wood burner and its associated bits need to go?

I do have my doubts about wood burners, somebody close to me has one and the smell and smoke from their chimney is very much reminding me of the bad old days of smog's. Brian

[larkim]

We've just not bothered stumping up the cash for replacement windows as the existing timber framed and float glass single glazed window look nice and are in keeping with the rest of the house. We just suck up the heating cost for aesthetic.

In terms of removing the rest, now that we know there is a bitumen and wood coating to the walls in that room, it seems sensible enough to consider that in the event of an electrical fire for example this would be much more flammable than most other constructions so wanted to replace. And in addition we need to redecorate the remainder of that wall in any event now that the new hearth / stove are in place so it was more a case of "doing a job properly", and if that involves removing all of the existing (but previously un-known) board from the walls then that's what it will take.

I'm not particularly concerned about making significant improvements to the insulation of the room, though if there is an opportunity to do so I wanted to investigate what the options were and whether there were any downsides that I was unaware of (e.g. creating damp where we have no damp, needing to comply with building regs, etc etc).

If its just a case of get the builders in and let them take care of it, we're happy enough with that as a solution!

[RJH]

Yes, I'd recommend celotex. 50mm has turned one of the coldest rooms in the house to one of the warmest. 25mm - makes a difference, but on hindsight I wish I'd gone 50mm.

The science on this is - complicated. Plenty of info available online. An anecdotal tip would be to take the board below the room's floor/ceiling.

Although it all looks a bit of a dog's breakfast, I don't see how adding insulation to the inside creates a greater risk of mould - heat from the inside is more likely to stay inside, reducing any bridging.

[Andrew]

Not if you tape all the joints of the celotex. This will be another impermeable barrier on the warm side which is what you need. Also needs to be hermiticaly sealed all round the edges too.

Celotex is closed-cell anyway. It is impermeable.

[tabbypurr]

sonably quickly in the new year. Not DIY, but wondering what input I shoul d / could have on the spec of what is put in place.

??m ruling out creating an air-gap with a batten frame etc), and at the moment are constraining ourselves to thinking about only having that one w all re-done, what are the recommendations for materials assuming we get eve rything removed back to the brickwork? Are we likely to be creating oursel ves some damp issues if we go for a top end insulating plasterboard etc?

money and less insulation - and IIRC may also be polystyrene foam, much mo re flammable than chipboard or anything on Grenfell.

coated with ali foil on the warm interior side.

new insulation, a recipe for damp & mould. I would not do that.

It would need to be sealed impermeably and stay so for life to work. Expect ing that from tape with the usual house movement is more than optimistic.

far from. quote:

I just watched this video

whic h shows 4 material samples sat on boiling water jars for 30 mins, and three of them transmitting significant amounts of vapour. The 4 materials were foamglass, PIR, perlite and rockwool. Only the foamgla ss didn't transmit significant vapour.

What would I do? Probably scrape the surface of the joints with an angle gr inder so damp can get out, and make the warm side as near impermeable as I could.

NT

[tabbypurr]

really it isn't, but it's not obvious. Most people seem to think damp gets in from the outside.

NT

[RJH]

Perhaps I should have added that *I* find it complicated :-)

A while back I made the mistake of reading this:

and in particular this:

Everything seems to be an indeterminate risk, benefit, un/intended consequence or cost.

And while I'd agree that damp in most circumstances comes from inside, understanding how it moves through an unventilated building takes some doing IMHO.

[Andy Burns]

"This video is unavailable"

[Brian Reay]

I'd look into 'dry lining', ideally with some insulation, and a vapour barrier.

I appreciate you don't want to sacrifice floor area but the heat loss though a single skin wall must be scary. Plus it seems there is a radiator on that wall- a 'short cut' for escaping heat.

Consult a reputable contractor- they may have some ideas re 'tanking' the wall, insulation, vapour barrier, dry wall. That should keep the insulation dry.

[tabbypurr]

d coated with ali foil on the warm interior side.

ets in from the outside.

terature-review.pdf

Yes in that whatever approach you take there are ways for things to go wron g. But the simple act of placing your VB on the warm side wipes out the ove rwhelmingly largest risk. Since things going wrong is still a very slight r isk, insulating in a way that can be undone if essential has its merits, a principle I've followed here.

All I can do is disagree. The physics is known and not complex, what gets p eople sometimes is that it's not what people tend to initially imagine. In short, damp moves from the interior to the exterior and evaporates.

NT