BAL Tiling Onto New Felted Balcony - Tile Advice

[p4ulo]

Hi ya guys!
I live in a flat, and as such I have to run most structural things by a maintenance company for approval.
I recently decided to fix my leaking balcony, and had a builder and roofer come around. The overall opinion was a combo of an old patio door allowing water in through rotten frame, and a failed asphalt underneath the existing tiles and around the edge.
So...
I had new patio doors fitted with a new lead tray underneath, then the roofer came around to fix the asphalt. I took up the old tiles, which were down very well stuck to the old asphalt.
He knew I wanted to re-tile the balcony afterwards, my original plan was to use 20mm thick Purbeck stone (other half's Dad owns a quarry!)

So.....for some reason the roofer guy has stuck down an all new felt covering over the top, its 2 layers, you know, the stuff that they heat up with a blow-torch to stick together, and the final top layer has got a sand-paper type finish to it. Its got all new lead flashing around all edges mortared into brick course.

I told him I wanted to tile over it, he said that he has previously over-tiled this surface with a sand-cement mix with stone tiles with no problems. However, I'm not keen....

My thoughts are, thin skim over with sand-cement mix to flatten off, stick down a layer of Schluter ditra using tile adhesive with an edging strip buried under it, then top off with tiles stuck down with an exterior grade adhesive?

I'm a bit annoyed, it wasn't really what I was expecting the roofer guy to do. We'd had conversations about a waterproof layer going down which I could tile onto (I was imagining a Schluter type product bonded onto the asphalt) and I could go straight onto it, as it is I've got a felted roof now, with ridges where the joints are, which I probably can't tile onto...

Any advice please chums?!

 

[hmtiling]

Tricky one. Never had to do it so wouldn't know if its possible as is. Possibly two part external leveller like bal acrybase and then ditra drain on top. I'd be ringing shluter and bal though.
Good luck!

 

[Bill]

If the 'felt' is bitumen type then just use an appropriate exterior adhesive - there should be no need for a ditra type layer as the felt will act as a decoupler. Why not try a stuck down tile in the middle of the balcony for a month and see if it is still stuck after the British weather has finished with it.

 

[One Day]

Read up on schluter terrace assemblies or the German company 'gutjahr'...

 

[steadsy-boy]

only through experience as a flat roofer for 10 years , we often layed tiles on to felt roofing systems , straight on to torch on and 3 layer felt sand finishes , primer back of tiles stick straight to felt using same bitumen that's used between felt layers , dust and done , cant see the problem even if felted over asphalt