On Jan 22, 10:56 am, NoSpam wrote:
Keith Dunbar wrote:
A very simple question - but I have no experience of doing this ever. I
need to create a 4" diameter hole in an outside block built cavity wall
for a ventilation outlet. What is the best way to do this? Is there
something I can hire that would make it very quick and easy?

Either hire a core drill or stitch-drill a ring of holes and then use a
hammer and bolster.
A bolster? My bolster is about 4" across. You need a 1" or 1/2" cold
chisel once you've finised with the stitching.

Also I need to cut a similar hole in a plasterboard ceiling - I presume
this is dead easy - best to use a jigsaw?

Use a small handsaw, it's more controllable in plasterboard than an
(electric) jigsaw

Again, I don't think that's the right choice of tool. If you have a
hand padsaw then yes, but I certainly wouldn't want to cut a 4" hole
with even my smallest handsaw (which is a small dovetail saw).

To the OP: I'd use the electric drill, but if you can get at the
plasterboard from above, it will be MUCH easier!