Plastering with one coat..

[ray316]

l'm plastering my chimney breast wall to cover where the coal fire was.
l have boarded the opening up and it needs building up by 50mm to get it flush with the walls.
l,m using one coat plaster and have put two coats on and have a final 10mm coat left to do, what l would like to ask you plastering experts is how do l get a smooth flat finish the same level as the walls l'm plastering up to.
As you can tell l'm no plasterer and this is my first attempt, the area is 4x4ft.

 

[Richard C]

Most undercoat plasters are applied to a thickness of 10-15mm maximum with 2-4mm finish skim & one coat can go up to 25mm but 50mm is way too thick. If its plaster board you’ve used you may well have exceeded the maximum weight you can hang off it & it may not stay flat for long. Why did you batten & board the opening so far back from the face of the wall?

Getting it flat & smooth finish on plaster is where the skill comes in & should not be underestimated; the forum archive has many threads giving hints & tips but the thicker you apply it the more problems you will have as a novice. Personally I never use one coat as I don’t like it; it takes an age to go off & never looks as good IMO.

 

[plstering]

id use gypframe and 12.5mm board 2coat skim sorted

 

[1john]

If you are 50mm out you need to start again 50mm of plaster is way to much to hang off of plasterboard.

 

[ray316]

If you are 50mm out you need to start again 50mm of plaster is way to much to hang off of plasterboard.

l did'nt use plaster board, l used screws to put osb board on batten built frame then put one coat plaster on in coats..

 

[plstering]

one coat on osb board wind up

 

[ray316]

one coat on osb board wind up

No wind up... what can happen by using osb board instead of plaster board, it seem to have gone on ok.

 

[Richard C]

one coat on osb board wind up

No wind up... what can happen by using osb board instead of plaster board, it seem to have gone on ok.

I’m conscious of your tiling post but, oh deary me, if that’s what you’ve done it’s a non starter I’m afraid. Plaster & any sort of timber do not go together; timber absorbs moisture from the plaster & expands, then the plaster sets, the timber dries out & shrinks back, the plaster cracks & falls off; it could take weeks (or even months with 50mm one coat) but it will happen. You may as well rip it down now & start again with plaster board cos it aint gona last long before it all cracks & falls off.

 

[ray316]

opps l'm papering over the plaster will that hold it together so the plaster does not crack and fall off

 

[Richard C]

opps l'm papering over the plaster will that hold it together so the plaster does not crack and fall off

Very unlikely.

 

[ray316]

opps l'm papering over the plaster will that hold it together so the plaster does not crack and fall off

Very unlikely.

Also a wall mounted electric fire is going up here with the brackets to hold the fire screwed into the brickwork, the electric fire has a wide span & depth . l cannot be doing with taking all my nice plaster work back down , when in time we decorate again and it cracks/falls off l will. Will the electric fire by ok wall mounted on wallpaper/plaster then the osb, any fire hazard here..

 

[roughcaster]

one coat on osb board wind up

No wind up... what can happen by using osb board instead of plaster board, it seem to have gone on ok.

 

[danielrobson]

dont want to sound thinck but whats osb board??

 

[Monkeh]

dont want to sound thinck but whats osb board??

An idiot trying to speak English.

OSB is Oriented Strand Board. Often known as sterling board.

 

[danielrobson]

thanks mate
i defenatly would not plaster to wood