Replies

1. 
   andyfew322 | Nov 08, 2008 04:39am | #1

   bump

    

    

    

   I'm just sayin'

2. 
   mike_maines | Nov 14, 2008 03:03am | #2

   Don't know, but you can try the johnbridge.com forum, they're the tile experts.

3. 
   arcflash | Nov 14, 2008 03:26am | #3

   I saw a guy tile an exposed porch with just Hardieboard. I haven't been back to that job to see whether or not it worked out for him.

1. 
   silvertip | Nov 14, 2008 04:40am | #4

   I mulled that idea over but worry about the freeze, thaw cycle if any movement would be more than the detra could handle.  Don't feel like doing the tiles twice.  My problem right now is if I do all that ditra recomends I won't meet code on the distance between top of deck and the door sill.  Code is 3" min. between the two.

2. 
   shelternerd | Nov 14, 2008 06:07am | #5

   We did that (tile on two layers of Hardibacker glued to each other floating over Ameridrain and EPDM roofing and it's held up swell to the easy winters we get here in NC...------------------

   "You cannot work hard enough to make up for a sloppy estimate."

4. 
   Sphere | Nov 14, 2008 12:32pm | #6

   No one can answer that, without a structuarl engineer getting involved (  for your saftey) try again later.

   Spheramid Enterprises Architectural Woodworks

   Repairs, Remodeling, Restorations

    

   They kill Prophets, for Profits.

    

    

5. 
   losh | Nov 16, 2008 11:19pm | #7

   The Ditra is placed in the system as an isolation membrane in this case. Any movement below in the wood or concrete should not transmit and crack your tiles. I have never used the product outside, but the principle should be the same.

6. 
   rjw | Nov 17, 2008 03:31am | #8

   >>If ditra is impervious to water then what is the need for the drainage layer.

   Stuff happens

   ---

   "Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive."

   Howard Thurman

7. 
   Dinosaur | Nov 17, 2008 06:37am | #9

   This strikes me as a very questionable idea. In addition to my doubts about the EPDM standing up to having a slab poured onto it (IMO thermal expansion/contraction will chafe through that rubber in short order), no roof membrane will last forever even under ideal conditions. And when it does start to leak there will be no way to patch the leak without expensive and invasive demolition.

   I have tiled over flat roofs in the past, but did so using Blueskin and Durock under the Ditra. Yes, the same complaint about demolition being required to patch leaks applies, but the overall cost of the 'sandwich' is much lower than what you're proposing, and demolition is much less likely to do structural damage (if your slab has to go, you're gonna need to jackhammer it).

   Finally, there is the weight factor. Are the roof joists on this garage rated to take an inch-and-a-half of concrete, plus tile and all the rest of it? That's a very big load; far beyond the standard load assumptions built into residential code tables. I'd suggest strongly that you get an engineer's upcheck on that before going any farther with this.

   Dinosaur

   How now, Mighty Sauron, that thou art not brought
   low by this? For thine evil pales before that which
   foolish men call Justice....