Tiling onto plywood

[flyfisher]

I've just moved house. In my previous house I had someone build me a fully tiled shower cubicle about 15 years ago. He used 18mm WBP on a 4x2 frame, a 1200x900mm shower tray with 3sided upstands under the tiles. Unfortunately, I don't know what adhesives or surface preparation he used for the tiles.

It has never leaked and none of the tiles have ever cracked or fallen off in 15 years of almost daily use.

So it can be done . . . I'd just like to know how!

 

[kilty55]

I've just moved house. In my previous house I had someone build me a fully tiled shower cubicle about 15 years ago. He used 18mm WBP on a 4x2 frame, a 1200x900mm shower tray with 3sided upstands under the tiles. Unfortunately, I don't know what adhesives or surface preparation he used for the tiles.

yes it can be done as can tiling direct to chipboard etc etc etc the list goes on

doesnt mean its correct though.....the failure rate in these types of prepared jobs is higher than it should be and as pros we cant be seen to be endorsing these methods as its our reputations that will suffer.

 

[flyfisher]

That's fair comment and I entirely understand a professional's position about using the latest and greatest.

My reason for being here is as someone who has taken on a large home renovation project. It has been a bit daunting taking on some 'serious' DIY but it has been an interesting and rewarding experience.

I may have made a mistake, but I have recently built a shower cubicle based on the same method described above, although it's a corner cubicle with two walls and a curved shower tray. I've built the walls on a 4x2 framework at 250mm centres with two sheets of 18mm WBP screwed on at no more than 250mm centres, so the only the only joint is in the corner. The shower tray feet sit on a concrete floor so everything is pretty much rock-solid.

Given that 'it can be done', what is the best way to tile such a shower cubicle?

I'm currently planning to use a Mapei 'shower waterproofing kit', but I'm not entirely sure about the best adhesive to use. Something like Keraquick perhaps, though I'm not sure if this HAS to be used with their Latex Plus additive if I've used the shower waterproofing kit.

Any advice gratefully received, even if it's not a ringing endorsement as such 😉

Thanks.

 

[Muse2k8]

You won't get advice about tiling onto ply walls sorry... It shouldn't be done and given that a) you know it shouldn't and b) the best material to use is a hell of a lot cheaper than ply; then there is absolutely no reason at all to be doing it sorry.

 

[Daz]

As you've worked out, the use of plywood in a wet or high humidity area is far from recommended. Given that you do not wish to replace the ply with a suitable tile backer board then the next best course of action is to fully tank the area, and the Mapei waterproofing kit is perfectly good if applied correctly.

The waterproofing kit will only serve to protect the ply from surface moisture ingress and will not add any strength or resistance to thermal expansion so you must use a flexible adhesive. I don't think you have advised what tiles you intend to use so we can only provide a general adhesive guide at this stage.

A flexible single part cement based adhesive should be adequate for use. I recently did a wetroom where the client had selected to have Gulf Stone on the walls, and although the walls were constructed using cement tile backer boards I still had to use Keraquick with latex (due to the tiles, not the walls), and be aware that this is not the easiest product to work with, so you may wish to engage a professional if you choose for the added strength and flexibility.

The wetroom above has failed due to the substrate and not the adhesives used.

Good luck and it will be nice to see some pics as you progress.

Daz

 

[flyfisher]

You won't get advice about tiling onto ply walls sorry... It shouldn't be done and given that a) you know it shouldn't and b) the best material to use is a hell of a lot cheaper than ply; then there is absolutely no reason at all to be doing it sorry.

The cost isn't really an issue at this stage as the ply walls are already in place, so the money is spent. But two sheets of 18mm WBP ply for £60 didn't seem too bad.

'Knowing' that it shouldn't be done is an interesting point. While not in any way pretending to have much experience in such matters, all I did know is that the shower tiled-plywood shower cubicle in my previous house performed faultlessly for about 15 years, so I simply copied that. I only started to realise my 'mistake' when looking for a suitable adhesive.

I wonder how people built shower cubicles in the days before fancy tilebacker type materials?

 

[flyfisher]

As you've worked out, the use of plywood in a wet or high humidity area is far from recommended. Given that you do not wish to replace the ply with a suitable tile backer board then the next best course of action is to fully tank the area, and the Mapei waterproofing kit is perfectly good if applied correctly.

The waterproofing kit will only serve to protect the ply from surface moisture ingress and will not add any strength or resistance to thermal expansion so you must use a flexible adhesive. I don't think you have advised what tiles you intend to use so we can only provide a general adhesive guide at this stage.

A flexible single part cement based adhesive should be adequate for use. I recently did a wetroom where the client had selected to have Gulf Stone on the walls, and although the walls were constructed using cement tile backer boards I still had to use Keraquick with latex (due to the tiles, not the walls), and be aware that this is not the easiest product to work with, so you may wish to engage a professional if you choose for the added strength and flexibility.

The wetroom above has failed due to the substrate and not the adhesives used.

Good luck and it will be nice to see some pics as you progress.

Daz

Thanks for that. I called Mapei's technical helpline this morning and they said there should be no problems with a shower cubicle built with ply, providing it was securely fixed. They also agreed with using the 'shower waterproofing kit'.

As for adhesive, they said Keraquick with Latex Plus would be fine but suggested that Keraflex would probably be better, so I think I'll go with that.

The tiles are nothing fancy, just bog-standard 20x25cm ceramic ones.

I generally take plenty of photos of everything I do (the house is G2* listed and it's good to keep a detailed record) so I'll post some as things progress - but you'll have to be patient as I'm not the fastest worker. 😉

 

[Deleted member 9966]

I wonder how people built shower cubicles in the days before fancy tilebacker type materials?

I built my shower cubicle using regular 12.5mm plasterboards and tanked them with a Mapei tanking kit. Plasterboard tends to be more cost effective than ply in the general market place for a DIYer like me.

On the point you made about your property being Grade 2* listed, what implications does this have on the building materials you have to choose? Do you have a choice? Do you get any guidance?

 

[flyfisher]

I can see plasterboard would be cheaper than 18mm ply. I just went with the ply due to my previous (though limited) experience and my feeling that 12mm plasterboard would be too flexible - though I suppose it depends on the supporting wall of course.

The listing question is quite complicated and, basically, all alterations require Listed Building Consent and are considered in the context of the house itself. The important person for LBC matters is the council's Conservation Officer (CO), sometimes called an historic buildings officer or similar.

In my case, the house has different historical phases - not uncommon in old houses. My shower is part of some alterations to form a kitchen/utility room and a toilet/shower room located in the newest (18th century) part of the house, which is not deemed to be of any special historical interest. Thus, although I still needed to apply for LBC, there were no onerous restrictions except that the replacement windows had to be identical to the existing, but rotten, single-glazed ones.

Basically, the CO visited before my LBC application and we discussed my plans for the house. He advised what would be acceptable and we worked out a suitable method. We've had no real clashes, perhaps because I'm not trying to make wholesale changes to the existing 'fabric' of the house.

The main material stipulation is the use of lime mortars and renders in order to preserve the breathability of the house. Non-breathable cementitious mortar/render can seriously damage timber-framed buildings.

Otherwise, modern materials are acceptable as long as they are appropriate. For example, when I repaired the roofs, it was quite acceptable to fit a breathable membrane below the pantiles.

It might sound like a pain to be listed but a good CO is like having a free expert consultant on hand and fortunately ours has been incredibly helpful. At least the planning applications are free!

 

[Muse2k8]

The cost isn't really an issue at this stage as the ply walls are already in place, so the money is spent. But two sheets of 18mm WBP ply for £60 didn't seem too bad.

'Knowing' that it shouldn't be done is an interesting point. While not in any way pretending to have much experience in such matters, all I did know is that the shower tiled-plywood shower cubicle in my previous house performed faultlessly for about 15 years, so I simply copied that. I only started to realise my 'mistake' when looking for a suitable adhesive.

I wonder how people built shower cubicles in the days before fancy tilebacker type materials?

And plasterboard is about £5 a sheet 😛

Fair enough if you have already built the support then it's unfair of me to not be constructive.

As has been mentioned your next step will be to use a tanking kit such as the bal or mapei one. Not sure about mapei but pretty sure if your tiles fail using bal they won't accept any product fault if you tiled onto ply.

Again as mentioned use a cementitious flexible adhesive. Do NOT use a ready mixed tubbed adhesive. Ready mixed works by dispersion of the water it contains and moisture will reactivate it causing it to fail... Long before the ply would!

Ensure you use adequate stress gaps at joints and do not fill them with grout, only use a good quality Silicon (you can get a nice one to match your grout 🙂).

Best of luck and enjoy your DIY project. I love doing work on my home... If only I got paid for doing it! 😀