Replies

1. 
   BillBrennen | Sep 18, 2007 08:05am | #1

   RRR,

   3 things:

   1. If you fill in your profile to show what area of the world you live in, it helps us answer your question better. I don't know if it freezes where you live, for example.

   2. The John Bridge tile forum is a great additional resource for tile related questions.

   3. Schluter states to use unmodified thinset with their Kerdi membrane, but skilled users can bend that rule when they fully grasp the reason for it. Bending the rule invalidates any Schluter warranty, express or implied.

   I hope this helps.

   Bill

1. 
   user-69050 | Sep 18, 2007 02:53pm | #2

   Your missing or not understanding one important item. Ditra is for the floor and Kerdi Band is used to waterproof the seams of the Ditra. Go to the Schluter site and check out there videos regarding exterior installations. Then call them!
   Jim

2. 
   RRR | Sep 19, 2007 06:40am | #3

   Thanks Bill for your reply.
   I have updated my profile and indicated that I'm in Toronto, Ontario, Canada.
   The weather here fluctuates quite a bit and during the winter the temperatures drop down close to freezing. Then again with all this environmental changes who knows form day to day!My concern now is with the temperatures dropping down to below 10 degree celcius ( 50 degree Fahrenheit) at night will have an impact on the curing of the thin set used.

   I have seen the ditra product used outdoors on walkways in commercial locations.
   My concern is applying the ditra onto the concrete slab of the exterior porch which has a garage below. i have never seen the ditra product used in this application. I haven't seen or am aware ofany other product thats acan be used for this application.RRR

1. 
   BillBrennen | Sep 19, 2007 07:32am | #4

   RRR,It seems like the Kerdi membrane would work for what you are doing, and yes, the thinset will cure slowly at 10 degrees C. So long as the thinset can go a week without freezing, it should be fine. If it gets daytime sun, tenting with clear plastic sheet will hasten your cure by day and retain more heat at night.With porcelain tile you will need to use unmodified or only lightly modified thinset. The highly modified products need to actually dry in order to get their full strength. Porcelain is a vapor barrier, so large format tiles would take many weeks to cure, by which time it may freeze, so no dice. With unmodified thinsets, the cure is not drying-dependent.Bill

1. 
   user-69050 | Sep 19, 2007 04:09pm | #5

   It's not so much the air temperature as it is the surface temperature that needs to be considered. If your daytime temp. goes above 50 degrees it will take a considerable amount of time for the concrete to reach that temp. Especially if the garage is unheated from below. I have always used the 50 degree mark as the "shutoff" point during the day. The same is true in reverse for when you can start. The air temp is higher long before the surface temp reaches the required temperature. Again, I say to call Schluter and get the info direct from the source.Jim

2. 
   manoman | Sep 19, 2007 07:25pm | #6

   What you are describing as an 'exterior porch' sounds more like a roof, in that the 'enclosed garage' underneath is protected from the elements by the 'porch'. If you are relying on the membrane and tile to keep the garage structure dry, you are asking a lot, especially in TO with it's extreme range of temperatures.

   I would be inclined to apply a torch-on membrane and start from there. not relying on the tile etc. to waterproof below.