Any builders around for advice please?

[bearded bloke]

Thinking on as I sometimes do,given that you have previously used a pitch based product to achieve the desired effect,could you find a roofer that does hot felt,that is bonded onto the substrate with molten pitch,molten pitch will flow to level then scatter dry sand onto the surface before it solidifies.When the pich has fully set sweep off the excess sand,the tile adhesive will then bond to the sand that in turn is bonded to the pitch.

[green thing]

If you are heating the floor there will be alot of
Expansion and contraction between the diffrent
Layers and materials.
You can get flexible adhesives now suitable for use
On asphalt /bitumen floors.my only concern would be separation
Between diffrent Layers. .
When I bought my house it had a stone floor on sand with a cement screed
Then an asphalt layer then vinyl tiles then ceramic tiles on top.
The ceramic tiles would become loose and crack.
the floor would move and and clunk when you walked on it.
Also had a big problem with silverfish living between the layers.

Ripped the lot up put a 100mm of insulation /dpc /then concrete subfloor
with under floor heating running from the boiler. Had
The stone flags sandblasted relayed back onto the concrete subfloor.

Under floor heating with the boiler is very economical compared
To electric heating, we only have the heating on for an hour
To heat the floor and it remains warm all day
We have no more movement damp or silverfish.
It was lots of work but well worth it.
Most of my customers who had electric under floor heating
say it's too expensive to run on a daily basis.
Recommended insulation depth is now 100mm
Very little point putting down a thin layer down
As it wouldn't make much difference.
If you have a dry floor you could do a semi floating
Floor , you can get bitumen coated wbp plywood
Screw it down to the floor then tile on top.
This would give you a warmer layer under the tiles
And separate layers. The floor needs to be flat
And you need to leave 2mm gap between the
Plywood sheets for expansion and walls
You can flexible adhesive and grout suitable for timber floors.