Rectifying Render

[CeeVee]

I scratched on an extension with my nephew a few months ago, then left him to top it with his mate about a week later.

The owner of the property is very overbearing and insisited he PVA'd the scratch before it was topped :RpS_scared: :RpS_cursing:

Obviously the top has now blown, so we're off to rectify it.
What would you suggest? Take off the top coat and rendaid before topping? The whole thing now has PVA on it so I ain't gonna just go over it.

 

[flynnyman]

I doubt the pva would of caused it to blow, if it was scratched properly and the mixes were right it should of been sound.

 

[DannyMac]

I agree with flynny. It's something else that's caused it.

 

[lucius]

Would normaly agree but the amount of rain we have had lately may have caused the PVA to emulsify with the top coat getting saturated.

 

[CeeVee]

Yeah my experience from years ago is that it re-emulsifies and seperates the top from the bottom, so I just never do it.

Apparently today I find its just patches.
Its a restaurant, and I've seen the tw@t hanging ducting out of windows before now.

hhhmmmm......

 

[DannyMac]

Would normaly agree but the amount of rain we have had lately may have caused the PVA to emulsify with the top coat getting saturated.

But it doesn't just sit on top of the scratch, it will soak in. Unless of course he's put it on almost neat?

 

[spunky]

How can pva remulsify and have the strength to blow rock hard sand cement

 

[spunky]

If it did remulsify wouldn't it just soak into the scratch coat

 

[CeeVee]

Scratch coat is supposed to be waterproof isnt it? I mean the admix ie. Rendamix gets it part way there doesn't it?
Thats always been my understanding...that PVA is good on porous walls for skimming as it soaks in, but the scratch coat of render has a waterproofing agent, so it just sits on top.

 

[Curry]

When you take it off leave a piece in some water to see if there is a coat of pva. If there is tell the bloke to do one.

I think your right CV. The waterproof has stopped it from soaking in.

 

[DannyMac]

Why hasn't it all fallen off then?

 

[bubbles65]

If you're satisfied that the scratch coat is sound, just scrub off what you can then top it as you normally would...........I would be asking the nephew what mix he (or his mate) made it, and what additives went into it :RpS_thumbup:

 

[CeeVee]

Both fair points!

 

[Arti]

Think this is a case for D.I Nailswater..get on the bat phone marra..........:RpS_thumbup: