Yes you can.

is this on a concrete slab or on a wooden subfloor ?
Answer this first.

wooden subfloor with 1/4 inch hardibacker

On Wed, Aug 5, 2009 at 3:43 PM, barredrock <....> wrote:
[This message originated at GardenWeb]

thanks for your input so far. this is what im doing now on the bathroom floor, see what you think

so this is what im thinking. in this order, tell me what i am or aint doing right
thanks

1. I believe it is 5/8 tongue and groove osb
2. 1/4 inch hardibacker
3. suntouch heated floor mat embedded in modified thinset and let dry how long before applying tile?
4. Do i need a leveler????
5. ditra with unmodified thinset on both sides
6. tile
------------------------------------------

Answers

Step Zero is missing.
Step 1 is not enough.
Step 2 is good. With expensive screws.
Step 3 is good. Depends on the instructions on the bag. E.g. eighteen hours or so.
Step 4 not unless you think you need it.
Are these humungous tiles or puny tiles?
Do you have a 6' level and what does it look like when laid on the floor in various directions?
With thinset you can compensate easily up to a point.... but that all depends.

Step 5 may be unnecessary, but it depends on Step 1 and Step Zero (what joists you have)
Ditra is good for slabs that may crack a bit and widen horizontally.
It might help also on Hardibacker or any other CBU on wood.
But this has been debated a lot and never "proven" a.f.a.i.k.
If your floor is springy, Ditra won't compensate enough to make it worthwhile.

Step 6 what size is your tile?
Have you tiled before?
Do you know what slaking is?
Etcetera...

--
David

what is step 0????
when adding another 1/2 inch can it be plywood or should it be tongue and groove osb???
using hardibacker with the good hardibacker screws.
we have a 4 foot level and there is a slight lean on the floor, thats why i was gonna use a slc, but the osb is new and no spring to the floor.
12 x 12 tiles
i have not tiled but the father in law and wife have done alot of it, i do not know what slaking is

Try to not have multiple posts on the same topic. I replied on your other thread.

Yes you can Lay ditra over suntouch radiant heat floor mats.

Here is a link that might be useful: suntouch