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Water proof a concrete slab roof which serves as a roof-top deck

Ottawa OHara | Posted in General Questions on

I am looking for a solution that would add minimum thickness to the slab. The deck is surrounded by a railing which would have to be replaced to meet code if the deck surface is raised too much. Two inches would be OK. The initial thought is a membrane but I would like to have a ceramic or manufactured stone tile surface. Is there a membrane material robust enough to accept these materials applied directly on the membrane? Any suggestions for another finished surface?

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    I've done a few brick roofs that have performed well. Schluter Ditra shows a detail for it in their manual but the system we have used is cheaper and thinner. There is a picture of it here if you scroll down a little

    Cover your roof with Mule Hyde EPDM from ABC supply or equal to stop water penetration, cover this with Ameridrain dimpled plastic drainage mats (available at Lowes) lay 1/4" Hardi tile backer over that loose and then lay a second layer on top with thinset adhesive glueing the two layers together. This is held in place by gravity and the uprights for the handrails. Thinset tile, or brick pavers to the backer board. bind the edges of the brick with treated boards held off the edges of the roof with spacers to allow for sub-drainage.

    Total thickness is a little over one inch plus the tile or pavers. All components except the EPDM from ABC are stock at the Lowes in our area. Detailing the edge where the water falls off is tricky, you need to get it to fall clear of the bottom of the projection so it won't run down the wall but this is an issue with any flat roof structure.

  2. user-611330 | | #2

    One suggestion: American Hydrotech, a green-roof company, makes a nice waterproofing for cement decks. It is hot-mopped on like an asphalt roof, but actually penetrates the concrete and bonds with it. What is nice about it is that is not as vulnerable as sheet membranes, which lose their integrity if they get a rip or hole. You can then cover it with any kind of roof paver or tile...

  3. dhowarda1a | | #3

    I've used Crossfield Products 'Dex-o-tex Barrier-Guard' over 'Dex-o-tex A-81 Underlayament' on a number of projects with conditons just like you describe. The A-81 is floated to create the slope and can taper to a feather edge. The Barrier-guard goes over the A-81, then the tile can be thinset directly to the Barrier-guard

  4. Summers 44 | | #4

    As I understand your question, waterproofing this deck in order apply thin set and tile is all you want to do?
    Waterproofing the concrete should be accomplished using a product called StableCrete. More information is available @ Green Products Page. Search by CSI Section 03-05-00 [Concrete Waterproofing Compound] or just type in StableCrete. Material is Extremely Low VOC 13g/L, topically applied to your deck surface where it penetrates into the matrix to waterproof, leaving no film to cause adhesion problems with any coating, or in your case the thin set.
    A cemetitious leveling product may be applied, if a pitch to your roof deck is necessary. StableCrete should then be applied to the final surface prior to troweling the thin set. This application will waterproof the leveled deck surface to prevent water from the thin set from migrating into the host material, thus isnsuring a superior bond of the thin set.
    After your tiles are set and grouted, apply StableCrete to the grout joints to waterproof them as well. A waterproof grout joint will not absorb contaminates and spills can be removed to keep the joints clean and looking new.
    The railing you mentioned around this deck should not be disturbed as StableCrete does not harm Glass or Metals if it comes in contact with them. This will give you a waterproof deck and protect any steel from continued exposure to moisture and contaminates.
    Hope this Helps? Glenn

  5. Jabu | | #5

    Can you quote me on romiving slab roofing insulation for wter proofing and replace for 60m2. I need quote very urgently iam biiding for the job. If your are available i can deploy for the job in the evetuality of winning the job. Do you do quotes in Limpopo?

    Jabu 083 517 4770

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