exterior render using uniibond to prime bricks

[tiger]

:RpS_scared:I have started to render an exterior wall and used a normal unibond to prime the wall before applying the the scratcoat 4-1 with an addmixture of waterproofer, I have been told that because the unibond is not a waterproof type that it could lead to problems with integrity of the finished render due to the unibond reacting with the wet cement and not staying dry.
I would appreciate any advise please. :RpS_scared:

 

[henry]

Well tiger if your going to have problems it will be with slumping if your pva has seal the wall. Some how carnt see it happening. Any way years ago before we had all the modern renders ,pva was king used for everything . Ive seen dashing and rendering I did 20 years ago still on ,looking tired as it would. we used pva on them jobs.
You could even mixed neat cement and pva as a sluury coat .
It is the cracking what maybe a problem.

 

[tiger]

Thanks Henry, what is the waterproof pva used for anyway and do you think it best to continue the rest of the walls without any pva?

 

[Blade]

Agree with Henry , they say in theory Pva can emulsify if it gets constantly wet , but ive never had a problem with it , we use SBR if specified , which , aparently stays set !

 

[lucius]

There are other problems with it something to do with alkaline which ive posted on before info i got of another forum but to be honest ive just walked past a flank end i rendered in 1982 and the building inspector made us PVA it which was new to us and a load of rubbish, old London stocks drop of water and away you go anyway its still on the wall and looking good.

 

[spunky]

Why are you priming the wall mate?

 

[plasterjfe]

Lord above:glare:

 

[S a plastering]

if anything it should be eva why you priming the walls anyway dont understand

 

[ajplastering]

yea, i though you just wet brick then put on scratch coat - why pva or sbr???????????????