Bathroom walls and floor and Granfix

Z

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?
 
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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.
 
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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?
 
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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.
 
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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?
 
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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.
 
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You may have a couple of choices, one is to hack off the whole lot and dot and dab plasterboard to the walls...or perhaps mechanically/screw battons to the wall so you can screw plasterboard to the battons.

There are other methods but that means going into the realms of metal systems.
 
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Here's a massive picture of a cross section of the wall. You can see where the skim has blown off the face of the backing. Its hard to scratch the surface of the backing with a screwdriver. Does it look like render or browning?
wall.jpg
 
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So if I scrape off the blown skim and then prime with Primer G or similar then I should be good to tile?

Any advice on item 2 / 3 in my original post?
 
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I would try and get as much of the skim off, if you have a wallpaper steamer use that and keep it on the plaster for a while and will loosen it off and prime.
 
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zzr-matt said:
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?

Thats fine

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?

Is the chipboard 22mm thick and you have no bounce on the floor

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

The addy would be a single part flexible.
 
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If your going to use ply 18mm would be my choice, British Standards recommend a minimum of 15mm....you could even rip up the old chipboard stick a few extra noggins in and use 22mm ply.
 
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Understood. Should I be tanking the shower area? 1 wall will be aquapanel, and 2 walls the render mentioned above. I was going to tape and cover all joints with single part flexi adhesive.
 
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The aqua panel is not waterproof just water resistant, if your going to tank the shower area use 12.5mm plasterboard and tank that...should save you a few bob.
 
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Hi chaps, one of the rendered walls is savagely out of plumb. The top of the wall is around 30mm further in to the room than the bottom. I was going to plasterboard this with the board making contact at the top of the wall, and then varying thickness's of horizontal battens at 450mm spacing going down the wall. Is that the easiest way given that I probably cant dot and dab as there is nothing for the adhesive to bond to?
 
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Why not dot and dab strips of plasterboard to the wall let the addy go off then dot and dab the plasterboard onto the strips. You can plug and screw as well if you wish. Be easier to keep the wall flat and plumb
 
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My 1 day a week glacial progress continutes.

All the skim is removed and the wonky wall has been d and d and mech fixed. Ive then applied a mapei tanking kit in the shower area so finally its time to buy the tiles and addy.

The tiles are from the tile depot and are 300 x 600 mm voranda porcelain.

Id like to buy adhesive and tiles from the same place so it seems to leave me either own brand ronnie or a granfix adhesive. Any recommendations on either of them?

Do i have to prime the tanked area before tiling or only the non tanked?

Cheers for all the help so far.
 
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Bathroom walls and floor and Granfix
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Bathroom Tiling Advice
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