Christian McArdle wrote:

So 20mm high will be enough to stop the Granite cracking when the
uninitiated decide to sit on the worktop? How many should I put across? I
was thinking of one near the front and one in the middle. The rear will be
held by some 2x3 softwood bolted to the wall.

Remind me - what's the span?


I should just squeeze 20mm in. I've got around 45mm absolute tops to play
with. 40mm would be safer, making it easier to insert/retract appliances and
less likely to end in tears. I can't lift the worktop another mm without
serious issues elsewhere.

I've got to get the beam, slate, tile adhesive and sealant in there then.
I've already got the 12mm ply down, so don't need to account for that.

That gives:

Adhesive 3mm
Slate 12mm
Beam 20mm
Sealant 5mm

That gives me exactly 40mm, so it should be OK, provided I spread adhesive
carefully.

I take it I can just run a thick bed of sealant and let it dry? I don't
think I want to glue the granite down? Is there a more suitable material for
this anyway, such as laying thin MDF/hardboard over the entire space?

I wouldn't worry about gluing the granite down - it'll peel off easily
enough.


--
Grunff