Shower Tray Installation... has come unstuck :((

[Gooner]

Hello all...

I installed a shower base the other day (for the first time) and walked away confident I did an A1 job. As instructed by the shower tray manufacturer's instruction (marbletrend) I used a 12mm thick 4:1 washed sand/cement mortar mix as a bed and leveled it perfectly. Today I noticed it has come unstuck and I can basically lift the shower tray.

I have laid ceramic tile underlay on floorboards and placed the mortar mix directly on the tile underlay and then the shower base on top. I don't see why the base has come unstuck. (See photos attached). I am quite dissapointed because as mentioned above, I spent alot of time making sure the base was perfectly level.

My question is, what now? Should I rip it all out and start again? Instead of mortar mix, should I use a cement based tile adhesive. (The manufacturer also recommends this as an alternative, but is much more expensive).

Alternatively, can I leave the mortar in place and put a thin coat of cement based tile adhesive down between the base and the mortar?

Any advice would be greatly appreciated!

Thanks

[journeyman Mick]

If the mortar bed is still sound and you can peel the tray up off it, I'd stick it back down on the mortar bed with a couple of cartridges of a polurethane sealant adhesive like sikaflex or bostik matrix/seal & flex.

Mick

[Gooner]

Heyya Journeyman.

Thanks for the response.

Do you think ripping the mortar out and placing the polyurethane sealant directly between the cement sheeting and base is better? Or should I leave the mortar bed in place? As far as I can see, the bed is sound.

The installation instructions can be found here (http://www.marbletrend.com.au/downloads/public/Showers/Project%20Base%20Installation%20Instructions%206490.pdf). It states "*Do not use silicone and/or liquid nails to install base." I am wondering therefore if a flexible polyurethane sealant is suitable. I think it should be, as floorboards will naturally deflect and therefore I think there should be some level of flexibility between the base and the floor.

Can I ask what your experience is in suggesting this? Have you done this before? Do you do it for a living?

Just don't want to make a mistake during this step as it is critical. I shudder at the thought of having to remove the base after I have installed the villaboard and tiles. Would be like repeating half of the work again!!

[journeyman Mick]

Gooner,
I'm a carpenter by trade and have installed a number of them. I've also installed toilet pans on aluminium decks on boats where we couldn't screw fix through the floor because underneath was a sullage tank. Generally when all else fails sikaflex will glue it in place. I'd say that the manufacturer has specified a mortar bed so that the tray is fully supported. Leave it in place and use a heap of polyurethane.

Mick

[Gooner]

Ok thanks again Journeyman.

I will give it a try and hope it works.

I looked up the Sikaflex product. There seems to be many types of Sikaflex. Is Sikaflex Pro the way to go? (There are a few Sikaflex products).

What is the consistancy of the stuff when applying? When it dries, is it flexible to the touch, perhaps like a stiff silicone, or quite hard?

Much appreciate the advice :2tsup:

[journeyman Mick]

Consistency varies a bit from type to type. All will dry to a stiff rubber-like consistency. Best bet would be to buy a couple of bulk "sausages" of Bostik "seal and flex" as this would be the most economical way to buy. Apply with a notched trowel to form a 5mm or so thick bed. Tip: make a notched spreader out of a scrap of ply or similar or buy a plastic diposable one, you won't want to have to clean it after use. Clean your hands etc afterwards with metho (will remove 95%) and then wipe with thinners to get the residue.

Mick

[Outbackrr]

Keep us posted on how you go with the base Gooner.

[Gooner]

Ok, I went off and bought 6 tubes of Selleys polyurethane based "Adhesive and Sealant". At $15 each, its an expensive way to fix a shower tray to the floor!

I assume this stuff will do the job? (The Sikaflex stuff was almost $19 a tube. Could not find Bostik "Seal N Flex" at Bunnings).

I will leave the mortar base in place and add about a 1-2mm layer of the adhesive between the mortar and base. Hope it goes well. Hate to do it all over again.

[MurrayD99]

Our main bathroom is a construction site and we are waiting for tiles then installation of a heavy ceramic shower base and glass doors. Instructions sound a lot like yours (bed of mortar). 1 builder and 1 plumber have shaken their heads and walked away leaving a substantial amount of re-work to be done. Now the replacement team are getting ready. Thanks for the heads up (and thanks Mick).

[Tools]

Ok, I went off and bought 6 tubes of Selleys polyurethane based "Adhesive and Sealant". At $15 each, its an expensive way to fix a shower tray to the floor!

I assume this stuff will do the job? (The Sikaflex stuff was almost $19 a tube. Could not find Bostik "Seal N Flex" at Bunnings).

I will leave the mortar base in place and add about a 1-2mm layer of the adhesive between the mortar and base. Hope it goes well. Hate to do it all over again.


For the cost of all that silicone I would have ripped up the mortar and started again.

Tools

[jimc]

dont fret about the base being stuck. The morter bed is used to level the uneven floor to the marbletrend base.

If your base needs to be pulled from morter base to show it has not stuck to morter bed, then leave as is..after you install your wall cladding/tiles and shower screen will ensure it will never move.

If on the other hand the base flexes when you walk on it, then rip it up and do it again and do not put any weight on it to make it set.....I made that mistake with my first effort.

Its very easy to rip it up and redo. Just use a shovel and 5 minutes of your time and chalk it up to a learning experience.

[Gooner]

dont fret about the base being stuck. The morter bed is used to level the uneven floor to the marbletrend base.



Hmmm... You may be right here. In fact when I took out the old base I was able to lift it straight out. Wasn't actually stuck down at all. Must have been that way for years.

However, I would rather it be stuck down to ensure there is little to no movement. The adhesive I will be using has about 12% flex in it. I think a 1mm layer will be a good way to go.

[Gooner]

Ok... $75 worth of Sellys "Sealant and Adhesive" did the trick. The base is down now and not going anywhere. In fact, if I ever have to remove the base, I may have a hard time getting it out. I now have about a 2-3mm layer of glue between the base and the mortar. Some, but very little flex in the adhesive layer.

Unfortunately it is no longer "perfectly" level. On one side it is about 1mm out over 1000mm. I think I can live with that for now.