Hanging plasterboard on various walls

[ladwey]

Hi - I'd like to ask a bit of advice about hanging plasterboard, as I've heard conflicting things. I'm renovating a house that's about 130 years old. I've built an extension and taken down and added some internal walls. For the new stud walls I've sheathed them in OSB withacoustic insulation inside the cavity.

There are three kinds of walls I'd like to ask about: old external walls, old internal walls, and new external walls.

1. The old external walls are a skin of brick on the inside and mortar and flint on the outside. The old plaster/render was all blown inside and I've taken it off. Can I SBR then dot and dab plasterboard onto the brick, or is that a problem since they aren't insulated cavity walls? There's one upastairs corridor where width is at a premium; because the new sloped roof outside meets the external wall there, only the top foot or so is directly expised to the outside, if you see what I mean -- I'm particularly concerned about what to do here.

2. The old internal walls are also brick, and I've removed the plaster/render where it was blown. Is dot and dab ok here, since the boards won't be covering a cold wall? They're extremely uneven, so battening would be a real pain.

3. The new extension walls are thermalite blocks with an insulation-filled cavity. I've battened some walls out where pipe work needs to be accommodated. Is ordinary plasterboard ok on these battens? And is dot and dab ok on the remaining walls?

Thanks in advance for any help!

 

[Wayners]

Charlie DIY on YouTube has covered different ways to board old buildings.
I think first one he done was insulated board stuck with board adhesive.
Don't think he liked that system.
Last one I done I used insulated plasterboard stuck on with foam and then mechanical fixings through which were plastic.Timco plastic insulation fixings.
I also used screws and wedi washers in places.
All depends on walls but without a cavity a membrane, wooden batten, insulation and foil board screwed is another.

Internal walls have dpc?
Foam on plasterboard I've done.
Do you need walls to breath?

New build dot and dab board but make sure all 4 sides around board edge has adhesive of your get draft behind board.
I'm not expert on this so look up

 

[^woody^]

Use foam adhesive - the type specifically for boards.

Ease, speed, less mess and no thermal bridging from adhesive spots.

 

[ladwey]

Thanks for this all. Three more questions then:

1. Can foam adhesive expand enough to get round very uneven old walls? I understand dot and dab can go 25mm thick, which is what we're dealing with in some places

2. Do I need insulated / foil backed plasterboard on the uninsulated external walls?

3. Do I need to SBR before using the foam?

 

[Ivor Windybottom]

Get proper old-fashioned wet plaster, onto the brick.

Only dry-line if necessary - you only need to dry-line the thermalite block, which plaster would fall off.

Solid walls are vastly superior to dry-lined, especially if you ever need to chase out to fit something in future. Or in fact if you need to screw anything to any wall, ever.

 

[^woody^]

Thanks for this all. Three more questions then:

1. Can foam adhesive expand enough to get round very uneven old walls? I understand dot and dab can go 25mm thick, which is what we're dealing with in some places

2. Do I need insulated / foil backed plasterboard on the uninsulated external walls?

3. Do I need to SBR before using the foam?

Yes, the adhesive expands a bit then stops unlike the other foam that keeps expanding. You don't need sbr, but you do need to water mist the wall and board. Follow the instructions.

You don't need foil backed board for masonry walls.

 

[ladwey]

Ok great - so it sounds like

- dot and dab ok for internal solid walls / cavity thermalite walls, BUT foam or battens preferable

- foam and insulated plasterboard OR battens, PIR, and plasterboard for external solid walls

When do you need to use the foil backed board, out of interest? And are any of the above suggestions any different for bathrooms?

 

[noseall]

Get proper old-fashioned wet plaster, onto the brick.

Only dry-line if necessary - you only need to dry-line the thermalite block, which plaster would fall off.

Solid walls are vastly superior to dry-lined, especially if you ever need to chase out to fit something in future. Or in fact if you need to screw anything to any wall, ever.

Line them with 18mm ply first. Vastly superior to anything plugged and screwed.

 

[^woody^]

When do you need to use the foil backed board, out of interest? Amd areany of the above suggestions any different foe bathrooms?

Typically, timber frame external walls, bathroom ceilings where there is a cold roof void above, under flat or piched roofs, sometimes kitchen ceilings.