Job to small to get a plaster out, what to use!

[Dan]

Very good advice. Plaster board adhesive is great for setting boxes into walls where the background is weak or the existing plaster dodgy. Never tried mixing it with cement to be honest but might give it a go!

Don't mix Gypsum products with cement. They cause a chemical reaction and deboned.

 

[Barry White]

Don't mix Gypsum products with cement. They cause a chemical reaction and deboned.

This is not my field Dan but its common practice to add gypsum plaster to internal cement rendering or plastering its even used with lime and its known as gauging.
I have done this myself on the advice of a plasterer.

 

[Dan]

This is not my field Dan but its common practice to add gypsum plaster to internal cement rendering or plastering its even used with lime and its known as gauging.
I have done this myself on the advice of a plasterer.

Meh, a plasterer lol

"a chemical reaction occurring between the cement based adhesive and a plaster substrate, a known problem know as "Ettringite Failure".
Preperation - Pva Versus Primers | Always Use A Primer When Tiling, And Not Pva - http://www.tilersforums.co.uk/threads/pva-versus-primers-always-use-a-primer-when-tiling-and-not-pva.2511/

We have chemists on TilersForums who make barriers to prevent this because it used to be such a common problem. Plasterers being the worst culprits lol

 

[Wilko]

The interior of my house was stuffed up with care by previous use of PVA. Tiles all fell off the walls (exactly as described in the tiler's post) and one can peel the paint off the walls in sheets. The walls were plastered brilliantly and then given a heavy coat of PVA. The paint / tile glue never penetrated in any way and the wall reminds me of teflon coated fry pan for smoothness and non stick. Soooo much grief ...

 

[Barry White]

Just had a read Dan have to say I nearly fell asleep. Just wondering why all the plaster thats on top of cement rendered walls has not fell off and plaster on brick and mortar, concrete blocks etc. Like I said I am no Expert in this field but live in a home now worried about all my plaster falling off

 

[Barry White]

Did try the pva before painting once. Walls are only good for wall papering after that unless you sand them. Carnt beat milky matt paint on bare plaster IMO

 

[Dan]

Just had a read Dan have to say I nearly fell asleep. Just wondering why all the plaster thats on top of cement rendered walls has not fell off and plaster on brick and mortar, concrete blocks etc. Like I said I am no Expert in this field but live in a home now worried about all my plaster falling off

Because if it has been done right an acrylic primer would have been used to stop them mixing.

 

[Dan]

The two that don't mix is calcium sulphate and cement.

Cement based adhesive on calcium sulphate (gypsum) screed - http://www.tilersforums.co.uk/threads/cement-based-adhesive-on-calcium-sulphate-gypsum-screed.7346/

Happens on screeds, concrete, plaster and render and the fix is simple, buy a 12 quid bottle of liquid (primer) instead of 3 quid (pva).

But obviously that's more expensive than doing the whole job again inc thousands of pounds worth of tiles and whatnot.

Plasterers always being to blame usually. Sometimes a DIY tiler mind.

Either way, don't rely on anything you mix together that contains those two.

 

[haptism]

Gyproc Easi fill is what you need, plastered half my bedroom wall with it, sets quick, sands well easy to mix, use as little or much as you want.

 

[sparksburnout]

Blimey all we wanted to do was set a back box into a dodgy wall. I sand/cement rendered my sitting room walls and then finished with a topcoat of thistle board finish, lovely job even if I say so myself. 18 years later it is still looking great. Mind you not been in there for a week or so, probably won't be able to get the door open now for a pile of render behind it..........

 

[haptism]

How about barbecued meat and shoe polish, might look a bit iffy but it smells good, knarf knarf

 

[Richard Burns]

The formation of expansive ettrignite particles in high sulphate containing cementitious products is generally associated with heat treated concrete and does not usually cause problems in non heat treated materials.

 

[sparksburnout]

The formation of expansive ettrignite particles in high sulphate containing cementitious products is generally associated with heat treated concrete and does not usually cause problems in non heat treated materials.

Thank God for that, I was worried about getting to sleep tonight.