plaster advice

[vik2001]

Hi
im going to get my whole house plastered. i need to know when the plasterer comes in so i am knowledgable.
above my window frames is a mix of wood and bricks, so when he plasters around that can he get the plaster on the wood. he said to me if he uses pva directly onto the wood then renders followed by a skim it will hold?? is this correct?

also i have a wall, that has been glossed. how do i prepare this wall so it can be plastered?

 

[roy c]

Get another plasterer if he says he can pva wood and then coat it and skim it!!!!! Years ago we used to knock plaster board nails into any wood and leave them about 3/8 of an inch proud and then render over it so the sand and cement had a key. Nowadays you put expamet (expanding metal) over wood, two layers of it, and that gives the s/c grip. A gloss wall ,I would score it up with a stanley knife or grinder, depending on what is behind the gloss and then I would mix some sand and a strong unibond mix together(3-1) and paint it over the scored wall maybe 2 coats, then leave over night to dry. Then just before skimming it I would put a coat of unibond on (3or 4-1) and let it pick up then skim it.... Hope this helps..

Good Luck.....

 

[vik2001]

ok thanks
i queried this with the plasterer, and he showed me the pva he uses by everbuild and it says on the back that pva can be applied onto wood. he said he would apply it neat so s/c sticks. the wood is only really around the windows, and where the skirting boards are.
should i ignore what he says... would bonding go on better???

also if some1 can answer, when putting fresh plaster board ceilings directly onto joists, is it better to use screws or nails??

 

[noseall]

the reason you can use pva on wood is because pva is wood glue!

this does not alter the fact that the wood will expand, when wet and contract or shrink when dry.

you will end up with hollow plaster that will almost certainly be vulnerable to movement and subsequent cracking.

 

[vik2001]

ok let me put this in perspective. the walls in the bedrooms are bricks, but the bricks have been built up on top of a strech of wood to make up the wall. so basically the brick wall sits on the wood. the wood is only 2.5 inches high, and this is where the skirting would go after, but would it be ok to render the wood using pva, and then render over the bricks above also??

 

[roy c]

You don't put pva on wood and render!!!!! And if the skirting goes in front of the wood why would you want to render it anyway? In your first post you said the wood was above the window and a mix of bricks, that was the post and questions I answered. A "piece of wood" above a window is called a lintol.....

 

[roughcaster]

Roy's correct Vik,,,,,you did say it was above the window frame!! but I would still use wire lath over any wood that is going to be coated over.

Roughcaster.

 

[roy c]

Thanks rc I thought I was going around in circles for a minute