1920s brick cavity wall - dot and dab plasterboard

[johnhenstock83]

afternoon,

 

I'm after a bit of advice before I do anything stupid.

 

1920s house with brick/brick cavity walls (approx 50mm cavity, uninsulated), structurally sound, inner brick work seems pretty decent for what it is (no huge lumps of mortar "dripping", almost no missing mortar between bricks etc.). the story is quite long, but the short of it is that for this project, there's not much money, so getting someone in to do the work (e.g. hardwall + skim) is simply not an option. I suggested dot and dab plasterboard, as there is a lot of DIY resource and the cost of materials is almost nothing.

 

now I know dot and dab can look great and give you that straight wall finish, but I've done a bit of research and I'm in two minds about it. half the people swear that I'll end up with drafts, mould and falling pieces of wall, let alone damp behind (and as a result, IN) the plasterboard. the other half does it all the time, it seems to be the "standard" method aside from hardwall etc.

 

the room it will go in is made up of 3 external walls (first floor), but is a bedroom, hence no huge amounts of humidity. it's also uninhabited during the day and there are large windows for ventilation, let alone a capable radiator to keep it nice and warm. the ceiling is also properly insulated (and I mean properly: 300mm mineral wool, cut to the mm, laid exactly as required by the manufacturer), so I'm hoping this means there won't be an issue with heat, ventilation or excessive humidity.

 

will I regret getting it dot and dabbed? will the void between plasterboard and brick become this hidden from sight amalgamation of cold, humidity, drafts, mould etc.? or is it all overblown?

 

thanks

[nod]

In your case dot and dab would be better than hardwall 

Insulated boards would be better than standard wall boards (pink backed)

[joe90]

I dot and dabbed insulated plasterboard in an old cottage with solid 9” walls and it was the best thing I did for a 100 year old place. If dot and dab is done properly then draught will not occur, plus you said the brickwork was sound!

[johnhenstock83]

is there a dot and dab pattern that ensures a good fit? for example, not just dabs of adhesive here and there, but also a continuous line around?

 

thanks

[joe90]

@nod, your the best for advice on this!

[syne]

On 17/10/2023 at 11:26, johnhenstock83 said:

is there a dot and dab pattern that ensures a good fit? for example, not just dabs of adhesive here and there, but also a continuous line around?

 

thanks

Knauf have a bunch of technical documents on fixing and adhesive pattern, it was recommended  to do a continuous border around the perimeter of each board and 9 dabs inside iirc.  this was for insulated board, but would imagine something similar applies to normal pb.