Bathroom walls and floor and Granfix - TilersForums.com

[zzr-matt]

Its been a few years since I was last on here but I'm back as I have another bathroom to do This time I'm using 300 x 600 porcelain tiles. The local tile place is a Granfix stockist. They used to be Mapei so previously I used Primer G, Keraflex Maxi and Keraquick with latex additive. Whats Granfix like compared to Mapei?

This one has a selection of issues:
1. The walls are 75mm light weight blocks with a 10mm render with a 3mm skim on top. Unfortunately the skim is not stuck to the render and just comes away. The render (not sure if thats the correct name) is hard but feels a bit dusty to the touch. Much like if someone had just blown a load of building dust over it. Once I have scraped all the skim off I assume I can prime this and tile straight on?

2. I need to build a small section of stud wall in a shower enclosure. I was going for aquapanel onto the studs, tape the joints then tank the area before tiling. Does that sound ok?

3. The flooring is a mixture of P4 / P5 chipboard on joists at 450 centres. I was going to go over this with 12mm ply screwed to the joists and chipboard below but from what I have now read on here no more ply 6mm may be the way to go? Does this need to be glued and screwed?

Can anyone recommend the best Granfix adhesive to use for the above?

 

[White Room]

You say lightweight blocks, do you mean thermolites..

 

[zzr-matt]

yup that kind of thing. Easy to cut with a hand saw. The render has a very strong bond to the blocks

 

[White Room]

This is my personal view on those blocks, they can move and the render should be a weak mix which why it may show signs of dusting if it's a strong mix of render it can crack with the blocks....either way I would trying to remove the render and dry wall for the tiling IMHO.

 

[zzr-matt]

Im not sure if render is the correct term. It may well be browning?

To remove that will require some heavy sds action as its damn well bonded to the blocks. Im concerned that will destroy the integrity of the wall which wont be improved enough by a sheet of drywall?

No sign of cracking thus far at 30 years old if that makes a diff?

 

[White Room]

If it is browning which would have used for those kind of blocks and if you remove the finish you don't tile on top of gypsum undercoats primer or no primer also there are weight issues concerning gypsum plasters which is a max 20kg m2.

Your tiles are porcelain, how thick are they and do you have the means to check the weight of them.

 

[zzr-matt]

Makes sense, I hadnt appreciated you cant tile onto the browning etc. The tiles are around 8mm thick.

Can i just board over the browning or have i got to strip it all off?

 

[bugs183]

Just stick to Mapei as you've always done, i know no reason for you to switch to Granfix, other than cost, and it's not worth swapping cost and quality to save a few quid.

 

[zzr-matt]

If there was somewhere local who stocks mapei i would stick with them!

 

[White Room]

Makes sense, I hadnt appreciated you cant tile onto the browning etc. The tiles are around 8mm thick.

Can i just board over the browning or have i got to strip it all off?

How many m2 are there if you had strip the plaster....