New Build Wet Plaster or Dot & Dab on thermalite

[GHDirect]

I have been 3.5 years building my retirement bungalow out of traditional material.

Inside is Thermalite blockwork throughout.

Its not a passive house but I have tried to build in good standards and its well insulated. 

As an engineer I want flat walls and square corners but if I do it I'll be another 3.5 years.

The industry is saying Dot & Dab (which I can put up) but buy in the plasterer skill.

I am drawn to a wet plaster being a 10 mm render then 3mm skim as there is no air gap.

However cost and time are key considerations.

Any views or pro's cons welcome.

 

 

 

 

[ProDave]

The big issue with dot and dab is the risk of creating a "plasterboard tent" with the top of the gap open to the cold roof space. There have been plenty of thermal image pictures posted before about this.

 

If you are going to dot and dab, then parge coat the walls first to seal any air leaks and then pay attention to seal any gaps along the to edge to the roof space.

 

You could consider the modern method of making a service void. Screw 50mm by 25mm battens vertically to the wall and fix the plasterboard to those. It really makes running services easier. Use 50mm deep battens where pipework will run. Again seal the top to the loft space. A service void avoids the need to chase the walls for cabling and socket boxes and makes future alterations a lot easier.

 

Whatever you do, get the plasterboard skimmed for a better finish rather than just tape and fill the joints.

[nod]

48 minutes ago, GHDirect said:

I have been 3.5 years building my retirement bungalow out of traditional material.

Inside is Thermalite blockwork throughout.

Its not a passive house but I have tried to build in good standards and its well insulated. 

As an engineer I want flat walls and square corners but if I do it I'll be another 3.5 years.

The industry is saying Dot & Dab (which I can put up) but buy in the plasterer skill.

I am drawn to a wet plaster being a 10 mm render then 3mm skim as there is no air gap.

However cost and time are key considerations.

Any views or pro's cons welcome.

 

 

 

 

If you use wet Your stuck with High suction browing

 or gypbonding the whole surface

[PeterW]

Alternative is use foam to glue the boards on if the walls are pretty level - DryFix is the trade named one but there are others

[nod]

4 minutes ago, PeterW said:

Alternative is use foam to glue the boards on if the walls are pretty level - DryFix is the trade named one but there are others

That would be a long job

Drywall adhesives fine

But you must have a solid line of adhesive around all perimeters of walls and frames and sockets 

and as Dave has already pointed out Tape finish is rubbish 

[Nickfromwales]

You can D&Dab and leave the boards 1/4" short of the ceiling and internal corners. Then get a fine nozzle for a low expansion foam and go around afterwards, when the dab has died fully, to fill and seal up the junctions so you don't suffer any serious convection heat loss. D&Dab is rarely done properly so you'll need to be in attendance when this is being done if you decide to sub it out

[PeterW]

19 minutes ago, nod said:

That would be a long job

Drywall adhesives fine

But you must have a solid line of adhesive around all perimeters of walls and frames and sockets 

and as Dave has already pointed out Tape finish is rubbish 

 

DryFix is the foam bonding that can replace D&D - it still needs a skim coat and it’s not just for TE boards. 

 

We’ve done a couple of small rooms with it and I’m impressed as the boards feel very solid. 

[Nickfromwales]

7 minutes ago, PeterW said:

 

DryFix is the foam bonding that can replace D&D - it still needs a skim coat and it’s not just for TE boards. 

 

We’ve done a couple of small rooms with it and I’m impressed as the boards feel very solid. 

Walls have to be pretty spot on with no snots to use the foam. It's a baptism of fire if you've not used it before, especially if doing the whole house. 

D&Dab is easier if your used to it, but there's nothing stopping you from finding a gang that use the foam. 

[nod]

2 hours ago, Nickfromwales said:

Walls have to be pretty spot on with no snots to use the foam. It's a baptism of fire if you've not used it before, especially if doing the whole house. 

D&Dab is easier if your used to it, but there's nothing stopping you from finding a gang that use the foam. 

Think it would be very exspensive and difficult to use on a full house

Rrminds me of the poly cell  tubs for covering artex cielings 

[PeterW]

We’ve priced it up and for speed it’s as cheap if not cheaper than D&D as it works out about £1 per panel fitted. It can also be skimmed an hour later - that’s a big difference and it feels much more solid. 

 

That said, only got about 80sqm that is on block, the rest is on battens anyway. 

[MikeGrahamT21]

love the video they've done for the DryFix! Though as an addition to it, i'd be using a spirit level!

 

Very mixed opinions on the whole foam fix, you can get fire rated versions now, like DryFix which would be best. I remember looking into it for external wall insulation, and everyone said cement based adhesive, though there were plenty of big manufacturers using foam fix, i went with cement in the end.