What ratio ?

[brimplas1]

I do a lot of damp coursing in old brick houses and scratch with a 3-1 mix and top with a 4-1. But the house I am on at the moment has I kitchen extention out of a dense concrete block. Will my mix have to be weaker so it doesn't blow ?? Ta for any help

 

[Arti]

I would say so. But then again I only use renovating plaster so it wouldn't matter

 

[Builderboi]

Dense blocks can take a stronger mix than old bricks.. That sounds too strong on the old substrate

 

[brimplas1]

I agree pal but that's the spec of the manufacturer of the additive .

 

[CTPlastering]

Ive used that for the dryzone spec and soverign .... We thought it was abit strong like .......

 

[carlos]

Me I follow the spec and f**k it.

 

[BigK]

Too strong imo. It's all very well following specs to cover your back like but a lot of them are absolute bull.
Did anyone know gypsum won't guarantee any of their products on knauf or siniat boards?
I wonder why that is.......[emoji6]
Skim won't stick on MR board..[emoji42]
Need we go on?

 

[carlos]

I know what your saying. In the damp game it goes like this.

Damp firm inject.

Plaster replasters to there spec 3:1 blah blah.

There's a damp problem again 18 months on. Damp firm take
A sample of plaster to the lab.

Lab show mix is 4:1. Blame the plasterer and invalidate the warranty.

That's the trouble with altering the spec.

 

[Builderboi]

Seems they are relieing on the cement to do the damp proofing rather than the chemicals just my opinion

 

[carlos]

Yep seems like that. If the new dpc works and you treat the wall with an effective salt neutralizer, why can't you dab or hardwall?