Another ply question

[ds1980]

In process of a loft conversion. All new stud walls etc. bathroom ceiling is normal 12.5 mm plasterboard. External dormer wall is done in thermal plasterboard (polystyrene backed) one wall with 12.5mm plasterboard. Shower enclosure and wall is done in 22mm ply. Don't ask the reasons it's what I've got. All is reversible at present but a ball ache!! Plumbers and builders have said its all fine but I questioned the ply element as I remember reading stuff when doing our wetroom. Floor is tongue and groove 22mm chip with 5.5mm ply going down. Question is should I change all the ply for tilebacker board or is it workable? Sorry been a long day!! Tiles are porcelain 10mm (60x30) for floor and ceramic (40x25) 8mm for walls

 

[cam_low]

Walls change for backer board such as hardie

floor needs cement boards glued and screwed none if this 5.5 ply malarkey.

Porcelsin tiles ? Ask to see Tilers previous work in the flesh.

 

[ds1980]

Porcelain Floor Tile - Porcelain Floor Tiles - Floor Tiles -Tiles & Floors - Wickes
White Satin Ceramic Tile 25x40cm PK10 - Ceramic Floor Tiles - Floor Tiles -Tiles & Floors - Wickes


tiler is me and father in law. Tbh I trust him more than anyone he's been doing it 50 odd years but I know that doesn't make it right. you don't get problems with his work. He wanted to use aquapanel in shower. Chippies said ply would be fine and theyve done dozens of lofts like it again it doesnt make it right. Can I put backer straight onto ply? I think if its only 6 mm it should be fine. Assume other areas are ok?

 

[cam_low]

Tonight you are the second person who seems to know the right way to do it but just needs a little reassurance.


What happens when you soak timber in water? Expansion contraction, rot, bad smells? Ply in a wet area is totally unacceptable.
Over board with hardie and tape joints.
floor requires 6mm hardie glued and screwed. Ensure there is minimal deflection in the floor as possible before fixin hardie.


tiling has moved on ten fold since the days of ply and pva. (Never use pva but acrylic primer diluted to suit)

Get ur old man on here to sign up. Never to old to learn !

 

[ds1980]

? Aren't I asking how I solve the plywood problem? Didn't I ask if I can screw Hardi onto ply? Chippies put the ply in. Spent time to ask to try and resolve. Don't want to take it all out out but if I should I will no bother old man wanted to use cement board. Still assume rest of the plasterboard walls are fine? Will cement board floor ta

ps he hasn't got a mobile so I'm pretty sure he doesn't know how to use a computer but ill tell him ;-)

 

[cam_low]

Plasterboard walls are fine. If you re-read you will notice I said to overboard ply with cement boards and tape the joins (fibatape)

good luck.

 

[cam_low]

There are other options in the over boarding for walls option ie Marmox and Kerdi which are lighter and dust free so ask more questions if needed!

 

[ds1980]

Been looking at 4mm marmox will this be ok. Tight on room. Put it up before using washers is this still the case?

 

[ds1980]

ok have added 6mm prowarm boards to the plywood walls. Just wanted to check my work. Soory bit long......

Have fixed with drywall 40mm screws through to the stud work in majority of areas. Have had to just go straight into ply in a few areas (5%) but they seem nice and tight. Ive read i shouldnt use these screws but we used them in our wetroom and havent had any problems yet? Have used 40mm m6 washers with them all and about 20-25 fixings per board roughly.

I need to tape the edges and joints. ....what tape should i use? can i just use plasterboard scrim tape? Am thinking it would probably be worthwhile to use waterproofing tape or alike in the corner and on the bottom edges of the shower?

Due to our shower enclosure having very little tolerance we are having to tile onto the shower tray rather than behind it. Is there anything else ill need to do this being the case? i have a feeling im going to go a little mad on silicone!

Prowarm (6mm) is going onto the floor. I was told to secure in four corners with same fixings and lay on bed of adhesive. Will be priming the floor with acrylic primer. It is 22mm T&G chipboard. The shower tray will be fixed using the same adhesive also. Looks like i should use a flexible cement based bag adhesive?

Other walls are plasterboard so hopefully just need to prime with the same stuff i do the floor (acrylic?) and tile using same adhesive?

Tiles being used are listed above.

Any help most welcome

ds1980

thanks

 

[Perry]

There are other options in the over boarding for walls option ie Marmox and Kerdi which are lighter and dust free so ask more questions if needed!

and also waterproof unlike hardi cement board