Plasterboard in Bathroom and Kitchen

[lastbuilders]

Hi,
I am doing a timber frame self build at the moment and have a query about the plasterboard in the bathroom and kitchen. I got plasterboard delivered along with the frame that is 12.5mm plain plasterboard. I have been told that you need to order stronger plasterboard to support cabinets in kitchen and special plasterboard in wet areas such as the bathroom?
Can anyone give me pointers on this? I have been told that an option is to put a sheet of ply behind the plasterboard in the kitchen for cabinets or to use plasterboard such as Gypsum Sasmox which is a lot stronger than standard. The studword is at 400 centers which I think may mean I don't need to ply or stronger plasterboard.
Any pointers would be appreciated as I am currently doing the first fix and will be slabbing soon. Also any sites with guidelines on slabbing would be appreciated as I am hoping to do this myself.
Thanks
Lastbuilders

 

[Carpenter]

Use Gyproc Moisture Resistant board (12.5mm thick) in bathrooms and shower areas. Use timber grounds behind any fixtures- either fix 4x 2" timber noggins between the studs to allow you to get a fixing or sheet behind the whole wall with plywood- althought this is wasteful of material and OTT. You will also need to incorporate timber grounds where you intend to put up shelving, shower trays, WC cisterns, heavy fixtures, lighting etc. It would be worth your while consulting an experienced carpenter before you start slabbing- errors and omissions at this stage are messy and difficult to fix afterwards.

 

[Touch Wood]

The green plasterboard also works very well under the floor tiles as it moves a lot less than plywood, so less cracks. There is a special knack to it so give me a shout if you are interested.
Sasmox or Fermacell are good alternatives to the plywood and plasterboard combination.

 

[tradesman]

If the studs are 400mm apart there should be no problem with the 12.5 plasterbard.it would be no harm if you put some extre cross pices between your studs at a height of 1900mm to take the wall units. that way you allways have a good fixing even if you have a narrow unit.

 

[Touch Wood]

Hello,

I seen your message in the thread that refers to using moisture board on the floor instead of plywood. I have always used 6mm plywood and a flexable adhesive and have had no problems so far. However, I am going to be re-fitting my main bathroom and the part I am dredding most is pulling the old tiles up along with the plywood underneath.

So, I am looking for alternatives for when I re-lay the tiles. I would imagine it would be easier to pull back up in the future, would you agree? Also, what is the knack in using it for floors?

 

[Touch Wood]

They checked hundreds of bathrooms that were 10 years finished in Finland and many of the tiles had cracked when they had used Plywood, this is the system they now use in Finland.
Cut the plasterboard and lay it dry at a 45 degree angle to the tiles, leaving a 10mm gap around the walls and 5mm between plasterboards.
Then lift each plasterboard and put expanding foam under each board in the following manner; I put 6 S shapes of foam on each full sheet, two on the top, two in the middle and two on the bottom a line of foam around the perimiter.
Lie the sheet on the floor, put a screw in two corners,
Don't drive these screws home yet as they are only to hold the sheet in place while the Foam goes off. The foam levels off any inconsistencies in the floor.
When the foam is dry put in screws every two inches and cut away any foam that comes out between the joints.

Fill the joints between sheets with joint fill plaster and scrim, sand down and you have a perfect level smooth area for laying tiles.
We used a Scandinavian product from Mira to put a waterproof breather membrane under the tiles and to stop the tile adhesive moisture being sucked into the plasterboard. This gives better adhesion.

 

[Carpenter]

Touchwood I think your plasterboard detail is interesting- I've never come across it before. I know plasterboard is sometimes suggested as a method of upgrading the fire resistance and sound performance of a floor. However I see one problem with your detail. You still need ply under the plasterboard so the overall floor build-up is quite thick and needs to be integrated into adjoining floor levels. If 19mm ply is fixed down to joists with screws and allowed to acclimatize before tiling everything should be ok, especially when a flexible adhesive is used. However your idea is worth considering.

 

[Touch Wood]

You are right, we took up the floorboards first.
UF heating cable can be added between strips of green plasterboard (2nd layer) and cover the cable with levelling compound to give a warm floor with thermal mass that doesn't get cold too quick.
Then tank the whole floor with Mira products to get a wetroom/UF heating combination.