tiling over two diffrent subtrates

[Freeze]

Darren do you think that fixing hardie over screed first, latex on top ,then ditra would be preferable to latex on screed ,hardie then ditra.
i honestly don't know my self .
I think you and I must be giving these Dutch tech boys some sleepless nights.
i am always been told by them that no one has ever asked the questions I ask before !,,but I am sure you are are asking similar

To be totally honest John Im not sure, the only reason we went Hardi first is that we wanted to bridge the biggest cracks in the middle of the boards, so by not levelling first the cracks were visible, didn't want the cracks on or close to the edges......you have got me thinking now whether it was best that way.

 

[jonnyc]

To be totally honest John Im not sure, the only reason we went Hardi first is that we wanted to bridge the biggest cracks in the middle of the boards, so by not levelling first the cracks were visible, didn't want the cracks on or close to the edges......you have got me thinking now whether it was best that way.

Darren I don't know myself but I can see the logic why you chose your route if you wanted to bridge the cracks in middle of boards as best possible.so there is a logic in our method of madness.i was thinking if slc down first then no danger of piercing pipes when screw fix boards if any pipes floated up .
but just goes to prove my theory that a considered methodology is one well worth looking in to.
how many tilers consider where they they start a run of insulation boards and where those joints will be in relation to ply board joints underneath

 

[TJ Smiler]

I have never screwed into SLC (Situation has never arose where i have needed too) although i know it's solid i get the feeling it it wouldn't grab a a screw (or plug) so well............... Not quiet sure why i feel that but it's just floating in me guts i guess. I think if i were in the same situation as you at the time i would have gone with the Hardi first on SPF and screwed then SLC on top too. Hmmm food for thought though.

I have also on a few occasions where i have had to go over two different substrates (where customer was adamant they don't want an expansion joint) set the floor out so i get a grout joint right on top of where the two floors meet and then opened up that one grout joint by a mm or 2 and then siliconed it with a matching color to the grout. I did one of these in August 2011 and have been back several times to do other works in their house and it is still in perfect condition.

 

[beanz]

I have never screwed into SLC (Situation has never arose where i have needed too) although i know it's solid i get the feeling it it wouldn't grab a a screw (or plug) so well............... Not quiet sure why i feel that but it's just floating in me guts i guess. I think if i were in the same situation as you at the time i would have gone with the Hardi first on SPF and screwed then SLC on top too. Hmmm food for thought though.

I have also on a few occasions where i have had to go over two different substrates (where customer was adamant they don't want an expansion joint) set the floor out so i get a grout joint right on top of where the two floors meet and then opened up that one grout joint by a mm or 2 and then siliconed it with a matching color to the grout. I did one of these in August 2011 and have been back several times to do other works in their house and it is still in perfect condition.

I think we'd all prefer to do it this way, but 9 times out of 10, it just won't work out because of impossible cuts elsewhere.