My early victorian building has a nice stone facade covering what
looks like a messy mix of mortar and rubble.
I want to fit a combi boiler and need to drill a 10cm hole for the flu
pipe. How can I neatly cut such a hole through this type of wall ?
My neighbours did this recently but it seemed that the builder took
three days and from the appearance and size of the resultant hole he
must have done it with a pick axe! I would like to be somewhat
Something to consider here is that when the core bit breaks thru on
the far side it can cause the surrounding brickwork to fragment a
I have found it is better to drill the small pilot hole right thru,
then apply the core drill from both sides, so that the large hole
created by the core drill meets in the centre of the wall (or cavity).
That way you get a nice clean hole both sides requiring only minor
In case no-one else mentions it, be aware that using a core drill can
cause a lot of fine powder dust. SWMBO can be useful during drilling
operations holding a vacuum cleaner hose just under the drilling area.
What sort of stone is it? My house is uncoursed random limestone, 2
foot thick, and one problem with using a core drill as suggested is
that although the inner and outer faces of the wall are firmly
mortared in place, the middle of the wall is loose rubble fill. I can
see this loose fill causing problems for any drill.
When my boiler went in, I removed the stones to make the hole then
rebuilt around the flue (with quite a bit of expanding foam in the
middle. The hole wasn't that much bigger than the flue though and was
probably around a mornings work.
SDS stands for splined drive system (CMIIW), but "SDS drill" tends to mean
beefy drill that will bash it's way through concrete and stuff in a way that
normal hammer drills can only dream of.
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