Thread: Steps to take in removing old plaster

You don't say whether it is a brick or weatherboard house.....but something suggests to me that it is weatherboard. True?

Removing old plaster is going to be very messy.......first thing is remove the skirts and architraves. Then lay some drop sheets down over the entire floor. Starting from the top of the wall then just flail away....I suggest that a wrecking bar would be helpful here.

Once you've lobbed all that in a skip.....something that will probably take a couple of days......you can insulate.

You probably would not have any sort of vapour barrier between the outside layer (weatherboards?) and the lining so you should fit something like Sisalation Tuff Stuff between the studs and against the outside lining...because you can't get it between the frame and the outside you'll have to cut and fit into each cavity between the frame......then you'd need a R1.5 wall batt for insulation. Alternatively you could do the vapour barrier/insulation trick in one go using a product like Air Cell or Protherm.

Then you can gyprock over the top...if you need to batten (although I'm puzzled as to why) then you can use metal furring channel which is simply screwed to the frame...

Check out Rob's www.how2plaster.com for some more info

Yes it is weatherboard! Do I really need a vapour barrier? I thought batts in the wall cavity would be ample. I think the battening out of the room is possibly just to level it to hang the plaster?!?

Donna, you definitely need to keep the lathes on the wall, on alot of the old houses noggins were used very sparingly and if you remove the lathes you will remove the structural strength in the walls i.e, in the worse case you could end up with the roof caving in.

One of my customers many years ago did just this. Got a phone call about midnight one night, him and his brother had decided to get stuck into a third of the house with half his footy team mates to remove all the old plaster. While one of the guys was outside he heard a groan, looked up and part of the roof had started to sag abit. One more wall and they would have worn the roof. So over I go, we finished up putting new noggins and studs where needed after supporting the sagged parts then fitted new plaster, cornice and painted.

That was 12 years ago and the house is still standing.

Hope it helps.

Ross.

i have never thought of battening out walls.
It would make it easier if your walls are hardwood.
BTW, what is the best way to attach plaster to hardwood?
cant get a screw it the bloody stuff.

bugsy, the plaster screws should have no problem going into a hardwood frame. If they dont go in first time, reverse the driver then drive the screw back in.

Donna, It seems like you are getting mixed information here.

For my money, I would be going back to clear frames, and working from there. It will be very difficult to insulate the walls with the lathes in place.

Did the plasterer explain the plaster and lathe method to you? In case they didn't, I will give you a quick outline. The method predates the current gyprok and earlier fibrous plaster sheeting. Once the house is framed up and weathertight, the walls are covered with thin timber battens called lathes. There is a small gap between the lathes. The plasterers then mix the plaster on site and render over the lathes, forcing mixture through the gaps between the lathes to bind it to the wall frame. To achieve a smooth surface, the wall is trowelled to the best possible finish, and sanded.

In this method, the timber lathes are an internal reinforcement skeleton for the plaster, and there are no external fastenings showing at the face. With fibrous plaster, the sheets are preprepared in the factory and incorporate a substantial amount of fibre internally as reinforcement. Gyprok is a sandwich of plaster mix between two layers of card, acting as external reinforcement. Both fibrous plaster and Gyprok sheets are trimmed to size and then nailed or screwed into place, and then the fixing holes and panel joins are filled with plaster compounds and sanded flush.

With plaster and lathe, the lathes that I have come accross were about 25mm x 6mm, with the gaps between about 6mm also. While the lathe setup would help to lock the studs in place and minimise flexing while the nails were sound and secure, they would do little on their own to brace the wall structure and prevent collapse.

As I mentioned earlier, it would be very difficult to retain the lathes and effectively insulate the walls. For this reason, I would slowly strip the plaster and lathe off part of one wall initially, maybe one third of it's width maximum. In this way, you can find out whether there is adequate bracing and noggins in the framing, or have a chippy confirm this for you. Only proceed to strip the rest of the walls when you know that the frame will cope.

Regarding the vapour barrier, you really do need to have one. The weatherboards should keep moisture out, but they swell,shrink, warp and they rot. Sooner or later, enough moisture will get through somewhere to dampen the insulation or the back paper layer of the gyprok, which will allow the sheet to distort and become weak, and probably pass a water stain to the painted surface. The best way to fix the barrier between the studs would be trim it to about 60mm wider than the stud opening and sandwich it between the stud and a Masonite packer strip, securing with staples at 150mm spacing through the sandwich. Bulk insulation can then be placed between the studs and against the vapour barrier.

Most houses old enough to have plaster and lathe will not have a straight and uniform frame, as in the p&l method, the plaster thickness can vary to hide frame defects. If you gyprok straight over the frame, the sheets will try to follow the contours of the frame and they won't give a flat wall. To avoid this, its possible to batten the wall, and by reccessing the battens into the frame or packing them out as appropriate, you can get the wall to finish flat and vertical. Check the window frame depth when determining your battening strategy, its a lot easier if the inside edge of the window is flush with the surface of the gyprok, otherwise you need to plane down or build up the frames to suit.

Originally Posted by fozz

bugsy, the plaster screws should have no problem going into a hardwood frame. If they dont go in first time, reverse the driver then drive the screw back in.

thanks,


also what about going for 13mm? thicker plaster instead of the 10mm while you have the chance?
I hear this can help with noise and is not much dearer