I have a customer who wants to cement a cermic mosaic to a substraight for a table top 4′ in diameter. This table will be used outdoors and, since it will be quite heavy, will remain out. The substrairt must be quit sturdy due to the weight and the inflexability of the ceramic tiles I would appreciate any suggestion for the sustraight and what to use to cement the tiles down. I have thought of MDF and cement tile backer board. They both have drawbacks due to weight, flexabilty and ability to hold up tp the elements.
Thanks for the help, so far this has proved to be a hard problem.
Mischa
Replies
MDF is not an outdoor product. Do you hve an issue with thickness? One readilyavailable product that you could use would be Advantech sub-floor material. It is an OSB product, but it is designd for adverse conditions. Some builders use it for countertops in kitchens where water damage from the sink is a realpossibility. Home depot and lowes usually stock it, or a reallumber yard. A 4x8 sheet of 3/4"material will be bout $50.
Cut out two pieces for the top and laminate them with a good water resistant glue and proper screws (not sheetrock screws). When the lamination is dry, cut to size and apply a coat of RedGuard roll-on membrne to allsides. It is a waterproofing membrane used for bathroom floors under tile. Set the tile with latex modofied thinset. For the best protection, consider using epoxy grout.
There re two forums that you might visit for more info. Try the guys over at Breaktime, and this excellent tileforum johnbridge.com
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Advantech is very water resistant as an osb board, but I wouldn't use it with rosin paper, nor use mdf/mdx.
I think it best to build a torsion box 3-4" deep, with regular BC or CDX ply, top and bottom. The waterproofing comes from your ability to seal the grout well, and by providing a drip edge around the apron.
I would suggest afixing thin cement board to marine plywood. The tile will bond better, provide an additional barrier against moisture and delamination.
I agree with Doug. A cement board over exterior glue plywood would be my choice. I would use a silicone sealent/adhesive to glue the tiles to the cement board and then use a marine caulking between the tiles. I would avoid standard grout.
You have some good suggestions here. But adding Durock or cement board to the table top means adding quite a lot of weight where you don't want it. As long as the tiles are grouted well(or caulked), it doesn't matter much what the substrate is.
How many times have you had to repair a tile job because some tiny crack allowed water to seep in and delaminate the plywood? Over time clients almost always let maintenance slip. The thin (1/4 inch) concrete board with the redguard wouldn't add that much weight and would protect against client stupidity.
Consider making the substrate out of 1/8 steel sheet/plate. After welding on brackets (and perhaps some stiffeners) to attach the top to the legs and apron. Send it out to be powder coated. Probably best to attach the tiles with a grout that will allow for the differences in movement. The extra weight, if any, will not be an issue since you have stated that it is going to stay outside and not be moved. Unless the powder coat is damaged, the legs will rot away long before the steel does.
Edited 9/11/2006 5:59 pm by QCInspector
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