Bad bricks

[noseall]

It's full of air bubbles, it's a sponge. I know what foamed polyurethane is like, it's definitely not rigid.

It's nothing like a sponge, more like coral.

I'd just get it wet plastered anyway, can't stand dry-lining myself. Seems a shame to take a solid wall and turn it into something that feels like a newbuild flat, that sounds like a cardboard box if you tap it.

A bit like a stud wall then, only a lot more solid.

Dabbing is also thermally efficient as long as it done correctly, i.e....

Dabber1

• noseall
• 9 Dec 2018

Untitled

• noseall
• 15 Aug 2014
• 3

Plus you can't reliably fix anything to it, at least not without a major operation. Chasing out for any future additional wiring is pretty much impossible.

Nonsense.

EDIT TO ADD: The sheathing effect of the dabbed boards also means that they will serve to stiffen say a poorly constructed block wall.

 

[Ivor Windybottom]

I'd have confidence in the wall you've shown, but that isn't how the typical builder does it.

Still a pain for any fixings and future work. Obviously you can get fixings and/or bugger about in various ways. Can't beat just drilling a hole and shoving a plug in.

If the wall's moving then you definitely don't want to rely on plasterboard holding it together!

The main advantage is that it's less skilled than wet plastering.

Any insulating effect is very compromised due to the amount of adhesive you've used. It makes bugger all difference on an internal wall anyway.

Lovely solid walls here. Hit them, they go "thud" and your hand hurts.

 

[noseall]

Lovely solid walls here. Hit them, they go "thud" and your hand hurts.

Lol. So any stud walls - you rip them out and replace them with what exactly?

 

[noseall]

If the wall's moving then you definitely don't want to rely on plasterboard holding it together!

Why not? I can displace at least 3 out of six blocks near the top of an aerated block wall I'm working on currently. When it is dabbed both sides, they will be rock solid due to the sheathing effect of the plasterboard. You would not get this benefit from wet plastering - ever.

 

[MH731Z]

It's full of air bubbles, it's a sponge. I know what foamed polyurethane is like, it's definitely not rigid.

Another of those cases where it's not right but it's OK. Might look alright at first, a couple of years later there will be hairline cracks down every joint as soon as someone leans on it.

I'd just get it wet plastered anyway, can't stand dry-lining myself. Seems a shame to take a solid wall and turn it into something that feels like a newbuild flat, that sounds like a cardboard box if you tap it. Plus you can't reliably fix anything to it, at least not without a major operation. Chasing out for any future additional wiring is pretty much impossible.

I cant do we plastering myself its a skill I'm quite bad at to be honest, when I asked a plasterer for just a skim coat for that area I was quoted £500, I can only imagine how much more wet plastering would cost...

having said that, I do agree wet plastering might be better and more useful when fixing things to the wall but I need to manage the budget

 

[Ivor Windybottom]

Lol. So any stud walls - you rip them out and replace them with what exactly?

Obviously you don't, I've no idea why you thought of that. But I also wouldn't buy a house that's built like this if I could avoid it, and wouldn't turn one with solid walls into cardboard unless there's a really good reason for it.

 

[Koolpc]

Nothing wrong with using the right 'foam' adhesive for plasterboard. It does what it says on the tin!

 

[Ivor Windybottom]

There are lots of products available that are useless for their intended task. Just because something's sold that doesn't mean it's a good idea.

I've never tried foam plasterboard adhesive. But I know that plasterboard is not resistant to bending, and polyurethane foam isn't rigid. I reckon if you push on a board bedded on foam it will move. Only a tiny bit, but enough to make a hairline crack in the skimmed joint.

 

[Koolpc]

Seen it used many times. Never seen any issues....

 

[noseall]

There are lots of products available that are useless for their intended task. Just because something's sold that doesn't mean it's a good idea.

I've never tried foam plasterboard adhesive. But I know that plasterboard is not resistant to bending, and polyurethane foam isn't rigid. I reckon if you push on a board bedded on foam it will move. Only a tiny bit, but enough to make a hairline crack in the skimmed joint.

You are aware that you can get insulation backed plasterboards, don't you?

 

[opps]

Slighty off topic, but the bar manager in my local pub asked me to sort out a couple of floor boards that were bouncing where they reach the tiled parameter The cavity below is pretty shallow. I drilled series of holes, squirted in expanding foam. 3 months later, those floor boards are fine. Nah, it was not intended as a long terms fix but X amount of people have walked over it in the meantime.

 

[mrrusty]

Plasterboard's not usually attached with foam, it will be too flexible so the joints will all crack.

@Ivor Windybottom - You really should try it. The correct plasterboard adhesive foam works extremely well - it's rigid, very easy to apply, and is designed for the job. It makes a very solid wall. Where it falls down is if the wall is uneven and you want to knock the dabs to adjust the board into line - foam works best on a flat wall where each sheet can be consistently applied. - The foam tends to end up a bit thinner than a dab. You do have to watch for initial expansion pushing boards out of line a bit before they go off.

I can assure you that applied correctly the joints do not crack. At all. (the compressive strength of expanding foam is about 5 tonnes/sqm @10% compression)

"DuPont™ Insta Stik™ MP FC is available as gun and straw foam
adhesive. It is applicable for vertical and horizontal bonding
of most common building materials such as insulation boards
and plasterboards."

 

[Ivor Windybottom]

You are aware that you can get insulation backed plasterboards, don't you?

That's PIR or PUR, not polyurethane. Totally different material. Plus it's a complete sheet and bonded to the plasterboard. Between them, the sheet is rigid.

I've got no doubts about the strength of squirty foam, I've seen it used to raise sunken driveways by drilling a few holes and squirting it in. Amazingly it will lift tons of concrete and permanently hold it. But a sheet of concrete is rigid, plasterboard isn't.

Anyone who's trimmed the stuff after setting will know it's more like sponge cake than PIR (Celotex).

It's probably OK, but something rigid must be better. On the other hand, it does insulate so reduces the heat loss.