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View Full Version : Slate chalkboards in shower

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cmz115 - Mon Jan 4 13:05:48 2010
First, some background. I built my own house 5 years ago and never finished the shower in the master bath. The plumbing was roughed in and I installed a 36"x48" Kohler cast iron shower receptor. The drywallers hung GWB on all three walls when they did the rest of the bathroom. We have used it for storage ever since. I have since acquired a large lot of old slate chalkboards (roughly 4'x4') and would like to use them for the shower walls and finally give my wife her own shower. Now the questions. My plan is to use kerdi directly over the GWB up to the ceiling. What size notched trowel to use on the walls and the backside of the slate? From everything I've read, no sealer is preferred but that makes me a little nervous. Are there any other potential issues I should be aware of? Thanks in advance. Craig

Edthedawg - Mon Jan 4 14:19:53 2010
Welcome, Craig :) You have an innerestin' project you're looking to try there. I'd wanna take a chunk of that slate and stick it in a pot of warm water for a few days, and see how much it breaks down. A lotta slates aren't suitable for shower/tub use because that happens. If it holds integrity, and is very flat on the back, you should be able to do it. When you say GWB you mean greenboard / MR sheetrock, right?

Davy - Mon Jan 4 14:57:13 2010
Hi Craig, welcome. Schulter recommends a 3/16 x 1/4 inch notch for the Kerdi. I would probably use a 1/4 x 3/8 for the slate. Add all the light you can in that shower. It'll be dark in there. :)

mossypath - Mon Jan 4 23:43:26 2010
I love old chalkboards for tile work . I had put cut chalkboard in my entryway and you could not ware it out . When I did take it out I reused the bits I could save on my new floor . The slate is dence and suited to use in a shower . Think of a old slate roof . There or some things that you may want to think about before you do a large amount in a shower . It is dark and will show dirt and water spots . 4'/4' are large sheets and I would use a larger notch trowel 1/4 3/8 or even 1/2 1/2 if your walls are not dead on. Cutting is not hard but you will want to use a hand held wet saw http://www.contractorsdirect.com/Tile-Tools/Hand-Held-Saws.It will give you nice cuts . All the slate may look the same but the different thickness will show up and will be hard to deal with if you don't cut the slabs down in to smaller tiles. lay it out on the floor and check to find ones that will match up with each other. You could use your slate mixed with another stone or tile and come up with something that looks great and use the left overs for other projects .I cut a scrap and mounted it on my sons door so I could send him nice little notes . What ever you do, we are here to help Just ask:tup2:

cmz115 - Tue Jan 5 12:43:20 2010
Thanks for the responses. I do have a few more questions. What should I use for the joints? I'm leaning towards caulk over grout. My first thought is a black silicone. I was planning on having all joints be about 1/8". The slabs are all a uniform thickness and I will make sure all the edges are straight and square. What is the preferred method to seal the kerdi to the shower receptor? I have the kerdi handbook and they show one method using some sort of caulk. Any thoughts? And yes, the GWB is MR drywall. Thanks again. Craig

Davy - Tue Jan 5 22:11:28 2010
Craig, it's probably Kerdi fix, it'll stick to about anything. I would use sanded black grout. Silicone would be shiny and wouldn't look real good up against a flat black chalk board. :)

cmz115 - Wed Jan 6 07:33:49 2010
Davy, Good comment on the shiny black. Maybe a dark grey caulk (silicone?) would be better? As for grout, can I use a sanded grout in 1/8" joints? I also thought that it was not a good idea to use grout in the corners and where the slate meets the shower receptor. What would you use? Thanks. Craig

cmz115 - Wed Jan 6 13:27:19 2010
Another question... Since the chalkboards are smooth on both sides, should I do something to the back to allow the thinset to bite into? One thought I had was taking an angle grinder and cutting a bunch of shallow grooves in a crosshatch pattern. Is that overkill? Thanks. Craig

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