How thick can plaster be

[el_caro]

Not as thick as some hey.

I have a brick wall that has been extended and is not straight. It has a bow in it of about 30 - 40 mm due to the extension. I want to plaster and tile the wall and would like to get it straight. Can it be plastered in the low area up to 40mm thick say down to about 10 mm at the ends of the wall? I thought maybe plaster in 2 goes and let the first one cure a bit before the final rendering.

Any thoughts

Cheers
Juan

[pawnhead]

Yeh you'll need a couple of scratch coats.Usually no more than about 15mm thick, or it just falls off under its own weight. Before it's totally set, run score lines all through it so it provides a good key to subsequent coats.

[memphis]

is the wall already plastered? why not do a basecoat of cement render to get the wall straight, then put on the thin plaster coat.

[juan]

The wall has had the original plaster removed and then the wall was extended about 1.8 m in length and that is where i was not as careful as I should have been.

So if I understand you I should put on a coat of cement render to correct the hollow and then scratch it up and let it set before getting in a real professional to do the finish coat and skim coat? I am trying to keep cost down.

[rod@plasterbrok]

You could consider using battens on the wall and line it with either villaboard or wet area plaster board.

The battens can be packed out straight and level.

If you were not tiling I would suggest sticking on blocks of plaster with cornice adhesive or masonary adhesive to level the wall then stick on plasterboard onto the leveling blocks. See and example here http://www.how2plaster.com/stickonplaster.html

Tiles should not be applied to plasterboard or villaboard walls where the board is stuck onto masonary. For a tiled wall the plasterboard or villaboard must be mechanically fixed with screws or nails with no adhesive behind the tiled area.

I have posted this option for the benfit of others with a similar problem.

[juan]

Sorry Rod but I do not want a false wall with villaboard, want the real thing.

Cheers

[rod@plasterbrok]

[sydneymick]

technically cement should not be more than 15mm thick but thats never followed really.
I agree with the post a bit higher. 2 scratchcoats. as a filler.
first apply by trowel and pass a straight edge over the bricks in the high spots to ensure no cement is higher than this point. Try not to coat to thick. it may look good as you walk away but over next few hours, its own weight will pull down onitself causing some uneven, bubbled areas which could drum.
as it dries, pass something rough like a broom or the trowel edge at 90 degrees. the next coat will now have something to bond to.
if the brick extension is diffrent types of bricks, it may be a good idea to put some mesh over the joins (nail a sheet on). This way as the bricks expand at diffrent rates, your chances of cracking is minimised.

Good luck

[juan]

Thanks for that. I will go down that track.

[bricks]

I've seen it done in two goes with a chicken wire type re-enforcing mesh nailed to the wall.

[Quikcote]

I've seen it done in two goes with a chicken wire type re-enforcing mesh nailed to the wall.

Yes, Ive worked on houses where it was a wooden stud wall, tar paper and chicken wire and two/three inches of render. Very basic.

[Grunt]

How thick can plaster be

Not as thick as some around here.

[rmartens]

This reply is maybe too late but you are right in the method you are trying. Sometimes you can apply a coat of mortar on the whole wall and thick on the area that needs building up. What I would do is get a long box rule about 3.5 metres long and run it horizontal the length of the wall and then you can see exackly where you are at.
When the wall hardens fill up the slacks applying more the the end that needs a big build up and come back to it in maybe a few hours. If I were to build up thick render I would not make the mixes no weaker than 6/1/1 6 sand 1 cement 1 lime and even if you apply more lime that is good say 6/1/1.5 lime even if this reply is too late it would be good for the next job