How do I use Wedi board on dot and dab wall?

[glass256]

Hi all, I am in the middle of renovating my bathroom. First of its kind for me! The walls were are all Plasterboard with tiles around the room up to shoulder height when standing in the bath tub. 2.7 walls on a wooden stud work frame, 1.3 walls relying on dot & dat adhesive against the grey breeze block wall.

So far, sanitarywares removed except for bath. Plasterboards also removed up to tile height for most of the walls with just the bit around the bath left. It just occurred to me that the bath is enclosed (in L shape) by plasterboard with dot & dab adheisive so no studs to fix the Wedi onto.

My uneducated guess would be to leave the existing (already hard & flattened) adhesive on the wall, add more all over the place and press the Wedi against it. The existing adhesive is effectively acting as the stud work to keep the board level. I don't know if normal plasterboard adhesive will stick the Wedi to the wall.

Is this the way or it has to be done differently? If so how please?

Do I use some sort of edge banding on the corners to make it more rigid?

When I install the bath, can I screw a wooden baton against the Wedi board to level & strengthen it at the wall?


Also
Thanks very much

 

[Ben-gee]

I would chip off the existing adhesive .

If the wall is flat and truish, acrylic prime the wall and then trowel it up with notched towel using tile adhesive and notch up the back of the wedi too- in other words treat it as a big tile.
Use a straight length of CLS to bang the board back firm and level - when addy dry, put a few screws and wedi washers - a couple per board at top to stop “peeling” - not really needed but do it anyway!

If wall is far out then use tile adhesive in dot/dab fashion as you would with plasterboard- in this case note where dabs are and definitely use screws washers through dabs once adhesive is set ( more screws in this case)

 

[glass256]

I would chip off the existing adhesive .

If the wall is flat and truish, acrylic prime the wall and then trowel it up with notched towel using tile adhesive and notch up the back of the wedi too- in other words treat it as a big tile.
Use a straight length of CLS to bang the board back firm and level - when addy dry, put a few screws and wedi washers - a couple per board at top to stop “peeling” - not really needed but do it anyway!

If wall is far out then use tile adhesive in dot/dab fashion as you would with plasterboard- in this case note where dabs are and definitely use screws washers through dabs once adhesive is set ( more screws in this case)

Attached is a pictures showing all the walls. Stud work on two of them but I may need to add more to it.

There seems to be a lot of acrylic primers. Any specific one?

I was hoping that I would only need to use the Wedi for the cut out area (right to the floor). Maybe go a little bit further just above riser shower rail. What you described above will mean I should really take the board complete off the widow side. I have to admit, that's a little daunting for my diy skills..... Could I not just get away with lots of adhesive behind the Wedi and hitting the board back as indicated .... the existing dabs helping to keep it flush the the plaster above?

By the way which adhesive will I be using between the board and the wall or does it have to be a Wedi specific adhesive?


Thanks

 

[Ben-gee]

If you can’t be bothered to do it properly that’s up to you, but don’t expect me to say yeah that’ll be fine.

 

[glass256]

If you can’t be bothered to do it properly that’s up to you, but don’t expect me to say yeah that’ll be fine.

ok, I might as well take it off i.e. long wall and one with shower riser.

Which type of adhesive between the breeze block and wedi? I’m assuming its will have to be one go mix considering the size of the wall to do?

Also not sure which primer

Thanks

 

[glass256]

Should the Wedi start from ceiling to floor or top of bath? I am assuming this will affect how I install the bath to make it sturdy.

Do I have to create a complete Wooden frame round the bath or rely heavily on adding batons to two sides screwed into the Thermalite block?

Thanks