Insulated gap filler??

[Andehh]

We had a large tiles patio, laid on 125mm + slab, it must have sunk or settled slightly, as the gap against the house opened up several mm in the last 2 years.

 

Now I could fill it with grout, and resilicone, but we have a large thermal bridge here, so having this air gap could actually help slightly by disconnecting the massive heat sink that is the patio.

 

Any recommendations for a filler material? Or just expanding foam? Trim back, then silicone? 

[Nickfromwales]

Mastic 

 

The last thing you want is water getting in there and freezing.