Refurbishing en-suite with new shower cubical & retiling honeycomb plasterboard wall

I am planning to upgrade my en-suit room 1.5 m x 1.6 m. Ripping out old shower unit and the wall tiles surrounding the shower cubical.

I will be fitting new shower enclosure 900 x 800 mm with new tray, retiling with ceramic 250 x 400 mm the shower area as well as the three full walls and half of the fourth wall that has window.

Problem is I have honeycomb (Paramount) plasterboard wall on two walls and other walls are hard (brick) plastered wall.

Question: if I damage the honeycomb plasterboard during removing of tiles, what plastering material should I use to patch any damage?

Before retiling I will be preparing the wall with tanking material.

Question: what is the best tanking product and sealing the tray to the wall surround?

Other walls (currently not tiled) have matt paint and I will be tilling these walls.

Question: how best to prepare the wall before retiling?

What is the best powder adhesive and grout product I should use? The walls have about 3 to 4 mm deeps (above the buried CH pipe work) so I will be using the buttering process and probably tile levelling kit with 5 mm spacer.

I am retired and want to save money by doing this project myself. I have read a lot about tiling, the above questions have not been answered properly.

The paramount board is fairly easy to deal with. Completely remove the plasterboard. Hack away the carboard with the back edge of a handsaw. This sounds daft but really works. Then gripfill CLS onto the back edge of the plasterboard that you are left with and screw on new P/board the next day.

As above to repair the paramount board but replace with Wedi or Jackoboard which will save on tanking ( just the joints)!
Sealing the tray - Dow Corning
Paint/emulsion must be fully removed and walls primed with an acrylic primer before tiling.
Look at the thread for adhesives and grout under their own section to see which is the most popular brands of powdered adhesive products.
For walls a 3mm joint is maximum you want to go with.
Good luck and enjoy!

Waluigi said:

The paramount board is fairly easy to deal with. Completely remove the plasterboard. Hack away the carboard with the back edge of a handsaw. This sounds daft but really works. Then gripfill CLS onto the back edge of the plasterboard that you are left with and screw on new P/board the next day.

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Thanks for the sound advice. This is a brilliant idea if the existing plasterboard is totally damaged during the removal of the tiles. If the plasterboard is not that bad, what plaster (one -coat or bonding plaster) should I use, before tanking? If i have to renew the plasterboard, what are the best water resistance plasterboard?
Thanks

timeless john said:

As above to repair the paramount board but replace with Wedi or Jackoboard which will save on tanking ( just the joints)!
Sealing the tray - Dow Corning
Paint/emulsion must be fully removed and walls primed with an acrylic primer before tiling.
Look at the thread for adhesives and grout under their own section to see which is the most popular brands of powdered adhesive products.
For walls, a 3mm joint is maximum you want to go with.
Good luck and enjoy!

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Hi John - thanks for the advice on all the questions. Can I rub the paint/emulsion with a sander to make the wall rough with sufficient keying surface for priming and tilling or do I have to totally remove the paint to original plaster surface? I will have a look at the other section for the adhesive and grout.

I’d remove all!
Once you start you’ll be surprised how easily it comes off.

timeless john said:

I’d remove all!
Once you start you’ll be surprised how easily it comes off.

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Thanks, John - i will see how i get on once i have started the project.

One more question. I will be tanking the shower area then I will be left with half of the paramount plasterboard wall that has been painted and two walls (brick) plastered wall again painted with matt emulsion. Do I have to use a different type of primers on these three walls (plasterboard & plastered)? I will be scrapping the paint off.

You can use the same primer however primers do vary and sometimes they are diluted in different ratios with water/neat depending on the substrate. Also the amount of coats required.

Waluigi said:

You can use the same primer however primers do vary and sometimes they are diluted in different ratios with water/neat depending on the substrate. Also the amount of coats required.

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Thanks for the confirmation. I am still waiting for a delivery of the shower tray and the unit. My current shower tray has been raised due to fitting kitchen type waste (big U connection), probably this is what was available in 1975. I am planning to install the tray on the wooden floorboard. What plywood and cement mix should i use? Marine plywood for 800 x 900 tray is very expensive (£40 to £50).

That was a bloody good year

Anyway, yes your best bet would be some 6mm Hardiebacker onto your boards if you don’t want them removed or if you remove them, some thicker tile backer board or to be perfectly honest, standard 18mm ply wood be fine.

Virtually all manufacturers recommend S&C, a weak mix 6/7 parts sand to 1 part cement. Some recommend a plasticiser. I probably prefer a rapidsettingAdhesive over S&C personally. I’ve trialed both methods many times and Rapidflex tips it.

Waluigi said:

That was a bloody good year

Anyway, yes your best bet would be some 6mm Hardiebacker onto your boards if you don’t want them removed or if you remove them, some thicker tile backer board or to be perfectly honest, standard 18mm ply wood be fine.

Virtually all manufacturers recommend S&C, a weak mix 6/7 parts sand to 1 part cement. Some recommend a plasticiser. I probably prefer a rapidsettingAdhesive over S&C personally. I’ve trialed both methods many times and Rapidflex tips it.

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Thanks, Waluigi, I saw Hardiebacker made by JamesHardie at top tiles and they do both 6 mm and 12 mm, but it says it only used for wall or floor tiles and it is very brittle. If I use this product, i assume i have to seal the gaps of T & G of the floorboard and make sure the floor is flat as the Hardiebacker is very brittle. Do I then just screw Hardiebacker to the floor without adhesive in-between. What if the floor is not flat? If the floor is nearly flat, say with a tolerance of 2 to 3 mm, can I screw a thin plywood to the floor and then screw Hardiebacker and then apply Rapidflex adhesive (what thickness??) and lay the tray. I know the tray will be slightly high, but I can run the water resistance vinyl click flooring under the tray and seal. If the floor is totally out then I might use the standard 18mm plywood as you recommend by removing the portion of floorboards.
Thanks for your advice on using rapidflex over S&C, what thickness should I use and which make to you recommend? What are the best slow setting (as I am a beginner) grey waterproof adhesive and grout I should use? Thanks for your time.

I have now started my en-suite refurbishment project.
Shower cubical out and old tray still in position.
Tiles removed and am lucky the damage to paramount plasterboard is to a minimum. Slight depression from 1 to 2 mm skim plaster coming off.
Going to remove the old adhesive by wetting with water.
Paint removed from one wall (brick and plaster).
I will use old tiles to check how good I am at cutting tiles. I have an electric tile cutter machine and manual kit.
Question:
What filler should I use to fill small damage to plasterboard? can I use the tile adhesive I am going to use for tilling? The plan is to use slow setting adhesive from Wicks or Weber make, any good suggestion.
Thank the shower walls only with Aquaseal kit and remaining walls (plasterboard and brick/plaster wall with acrylic primer. Which is the best make primer?
I will start to tile once the walls are prepared. Still, need to decide on the best slow setting advisive and grout.
As i am using 400 x 250 x 7 mm ceramic tiles from B&Q with 3 to 4 mm spacer. Are the use of leveling spacer good to use for beginner DIYer?
For plumbing, I am going to use compression isolating valves in the system for ease for future maintenance.
I still have to take the tray out and see the condition of the floor. The old tray has been with sealing strips which very watertight. has anyone use this and which is a good make that i can tile over it?

I still need to think of installing the tray to the wooden floor.
What is the best sealer to use around the gaps and between the tray and the wall? Dow Corning was mentioned above, but what spec.
See photos of my project.
I will keep posting until i finish the project but need some professional advice on the above question. Many thanks for spending your valuable time.

DIY Worker said:

Thanks, Waluigi, I saw Hardiebacker made by JamesHardie at top tiles and they do both 6 mm and 12 mm, but it says it only used for wall or floor tiles and it is very brittle. If I use this product, i assume i have to seal the gaps of T & G of the floorboard and make sure the floor is flat as the Hardiebacker is very brittle. Do I then just screw Hardiebacker to the floor without adhesive in-between. What if the floor is not flat? If the floor is nearly flat, say with a tolerance of 2 to 3 mm, can I screw a thin plywood to the floor and then screw Hardiebacker and then apply Rapidflex adhesive (what thickness??) and lay the tray. I know the tray will be slightly high, but I can run the water resistance vinyl click flooring under the tray and seal. If the floor is totally out then I might use the standard 18mm plywood as you recommend by removing the portion of floorboards.
Thanks for your advice on using rapidflex over S&C, what thickness should I use and which make to you recommend? What are the best slow setting (as I am a beginner) grey waterproof adhesive and grout I should use? Thanks for your time.

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Hi Waluigi, any professional advice on the above question will be welcome.

I have run into a problem. After marking the hole for a waste drain on the floorboard and checking under the floor, I find that there are two supporting joists across running very close to each other and sitting on a brick wall . There is no room to drill through. The drain is sitting right over a middle supporting joist and i do not want to cut the joist half way to weak its structural strength and would be difficult for maintenance. So now decided to raise the tray over the floor with raiser kit. My tray is Pearlstone resin based with a rough surface (stone & resin) at the bottom. manufactures instruct to use 6 adjustable legs to be screwed to the tray. Is this a good raiser kit compared to stick on pads, but the surface is rough? Also, see what how the pipework have been fitted into the Paramount board. i now need to repair this by fitting a small plasterboard, with filler and then tanking with Aquaseal tap & primer
. Extra work