Hi again,

I want to cut a hole for a new window in my house. It's got fairly standard cavity walls, built of concrete blocks. Actually the blocks are somewhat non-standard as they have foam insulation inside them (I mean inside the actual blocks - not inside the wall's cavity.) The only masonry-cutting tool I own is a 9" angle grinder. This will cut concrete blocks no problem, but only to about 3" deep. I suppose could hire a 300mm grinder for about £28 a day plus the cost of the cutting disk which I'm guessing won't be at all cheap.

Rotary grinders in general make an insane amount of dust. Is there any other tool that anyone can recommend? (I'm visualising something like a very large jig-saw with a diamond blade...)

Thanks for any tips you can offer,

JD