On 17/11/2016 19:45, Andrew Mawson wrote:
OK chaps - suggestions please.

I need to cut a 12" diameter hole in a workshop wall construction of
which is a single skin of 9" x 18" x 4.5" 7 newton concrete blocks. Now
I've all sorts of drills, angle grinders, hammers and even demolition
breakers, so the problem isn't removing the material, the problem is
doing it without the wall collapsing !!!

Current plan is drilling a circle of (say) 1/2" holes with a masonry
drill and wiggling it from both sides to hopefully join them up without
disturbing the rest of the structure. (I'll probably select a spot
where the hole is fully bridged by an 18" block - position within a few
inches doesn't matter.

Any other constructive suggestions very welcome.




Does it _need_ to be a circular hole in the _wall_ or would it work with
circular holes cut with (say) a jigsaw in 2 pieces of (say) plywood
which were screwed to battens (or "angle iron") in a _rectangular_ hole
in the blocks? You could make that rectangular hole with your angle
grinders, hammers, Chieftain tank or whatever other toys we can envy.

And if seriously worried about support, cut "slots" and fit uprights
before removing the central part. (Or should that be a slot and fit a
"lintel"?)

All capale of being tidied up with eg render to match the block?

--
Robin
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