Need some advice from the experts: Shower Remodel

[JazzGuitarGimp]

Hi All,

I have a shower stall that needs new waterproof covering. Three walls with a shower curtain for the fourth wall. I’ve stripped the old covering from the walls and brought it down to the green board. The plan is to cover the walls with FRP. We’ve bought the FRP panels as well as inside- and outside-corner trim strips. We also bought two gallons of the proper FRP glue, the v-trowel to apply it, and the roller to “iron” it onto the green board. I realize the trim strips are not going to make the inside corners water tight. So the plan is to go over the corners with an application of clear silicone calking, then use the end of a large popsicle stick to give the caulking a cove shape.

Am I headed for trouble here?

Ciao,
Lou

[Koolaide]

Hi Lou,
The silicone caulk is going to give problems IMHO. As I understand it they make a urethane for FRP, and if it were me that is what I would at seams and corners.

Many years ago I worked in a bodyshop. People often used silicone to seal windshields. Never worked (at the shop we used urethane problem solved). Same when I worked around the construction industry. Urethane on the other hand not only makes it water tight, it adds some structural benefit.

Hope this helps. Good Luck
Jim

[ChopSauce]

Urethane is what is used to make the joints on boat wood decks - if I'm not mistaking - and as a sealant for body extensions on cars. It might be far more durable. Smells bad, though.

[norburybrook]

in the UK, all joints between, baths/showers etc are done with silicone bathroom sealant. My shower cubicle corners which are tiled are sealed with a matching colour silicone sealant.



M

[ChopSauce]

For completion. Afterwards, I remember having repaired a leaking aquarium. I used some aquarium grade silicone so there should be very different qualities.

[Phil_S]

FRP = fiberglass reinforced panel? Here's my suggestion. Seal the corners with an application of fiberglass resin. It should stick to it and melt the corners together permanently. It is a very long time since I worked with fiberglass. As I recall, this stuff is a thick liquid. I'm thinking you might be able to paint it into the corner with a small brush. Done right, it will be almost undetectable.

Ventilation is required. You must use gloves to keep it off your skin. Otherwise, when it dries, it is like 1,000 tiny needles and it takes forever until you get rid of it. And if you get some on your hands, don't scratch your balls. It would be a good idea to practice on something first. Just make a fake corner with a couple of pieces of scrap wood. This stuff sticks to almost everything. The open time is short, so pour only small amounts from the can and be careful about how much catalyst you add.

[JazzGuitarGimp]

Thank you, one and all for your suggestions. I’ve been able to find polyurethane caulks, but not just urethane; is there a difference? I also kind of like Phil’s suggestion using fiberglass resin...

At this point, I’ve removed the green board on the two short walls as it was not in good shape after I removed the waterproof paneling. I’ve read cement board is actually preferred to green board these days. So I think I am going to apply Hardie Backer Board directly to the studs, then apply the FRP to the backer board.

Ciao,
Lou

[ChopSauce]

Did I wrote Urethane instead of polyuréthane? I intend the same thing. Dunno what you find in your area, but I have been using SIkaflex.

These cement board - provided we speak about the same thing - seem to be fairly durable, yes.

[Phil_S]

I've been thinking about what I said about using fiberglass resin. It would probably act as a chemical weld. If you want to do this, I recommend a test on the real thing, not on something else like wood.

I want to add a word of caution. If you do this and find the corner "weld" needs cleanup, this would probably be done by sanding. Perhaps I'd wrap a small diameter dowel in sand paper and work to progressively finer grits until it is polished. However, you must wear a good mask and be very careful not to breathe any of the dust. The fibers enter the lungs for a one way trip and are potentially quite harmful. I'd opt to leave it ugly and resist the urge. That is the reason to practice first or just use the polyurethane and work it with a popsicle stick. (Great idea for tooling the stuff.)

Good luck.

[tony hunt]

I'd like to offer some tips; I have about 500 hotel bathrooms to construct or renovate each year. The USA construction techniques, standards and terminolgy are quite different to ours in Germany. But basicly the principles are the same.

Green Board, I assume to be plasterboard impregnated for use in damp environments. This is what I prefer for dry walled shower wall cladding. The cement based boards are being pushed because the profit margins are higher. I only use them in a permanently damp environment such as a steam bath. The cement boards are prone to developing cracks at the joins and you need to deal with that in advance.

Polurethane, or PU as we call it, is excellent for unseen places. Sikaflex is a great company, but you need to get the right product because they have so many. I cannot advise on that, but don't go cheap. Silicone sealants are only for the visible caulking and have a short life of about two years.

My main concern is the suggested waterproofing with a glass fiber product. I have no experience with that and have no idea if there is any kind of tile adhesive system that works on that sub base.

We use a "painted" waterproofing with corner tapes which is produced by the company that makes the tile adhesive. That way you have a complete system that works together and a guarantee. We use products from a company owned by BASF and you can find them in any DIY home improvement market here. My advice is to get an all in one system rather than experimenting and risking water damage later.

All the best, tony

[ChopSauce]

For the sake of completion: Sikaflex 11FC is the ref. of the polyurethane sealant which I've been using, and which is also used for some automotive bodywork. The name of the company is Sika and they make other chemical products for construction.