My current water supply goes through the stone wall diagonally from 60
cm below ground outside to near floor level inside. It is 20mm MDPE, in
a 20mm drilled hole. Will my plumber protest if I put in a 25mm MDPE
pipe the same way? I presume the requirement for ducting is to reduce
the possibility of "hidden" water loss, but it would be really
inconvenient to dig up the floor. (Under a full cupboard that would
need emptying and removing, in a narrow space between an oil boiler, two
walls and the oil supply pipe.) Indeed, If I have to dig up the floor
it would probably be somewhere else. Did I mention that the rest of the
floor is quarry tiles that may well be bedded directly on subsoil?
Is it reasonable to just drill another 25mm diagonal hole?
I can't make any sense out of your post.
It's normal to duct any service through a wall or to permit withdrawal and
replacement where it would be difficult.
Or for protection against damage, mechanical or frost.
Only with gas pipes have you to watch out, there are stringent rules
governing gas pipe routes.
The question, such as it is, is how bad it would be just to drill hole
through the wall the same size as the pipe and pass it through. This
appears to be what was done in most old houses, and you usually see the
service pipe embedded in the concrete floor.
Whatever it fits though :) Probably 42mm if that's not too big a hole :)
I used 50mm though my floor to meet some 110mm that takes it in a smooth
bend under the wall and out the side 2' below ground, but that has loads
of slop. 42mm will probably be loose. Might even manage with 32mm but it
could be a tad tight depending on how sharply you need to form bends.
My only other comment is:
Diagonal drilling sounds fine but I would angle it so it comes out >18"
below ground so it's fairly well protected from frost by either the wall
or the ground.
When I were a lad, pipes were described by the Imperial insided
diameter, and presumably if we get rid of the common market we can go
back to this. But AFAIK all metric pipes are described by their outside
That's good to know, thanks. :)
So, you know what size hole it needs, but not how much water it will
deliver. There's progress, I guess.
With a standard masonry drill, it's easy to enlarge the hole by just
using a larger drill. Does that work with a core cutter drill, or do you
have to get it right first time?
FSVO easy, When drilling through a wall made of irregular, flattish
slate stones the risk of the drill binding between two of them, and
one's arms being turned into a twisted pair as in the Beano is quite
I am no kind of expert, but both in terms of accidentally slipping into
the old hole and of not having a useable pilot hole I suspect it is best
to get it right first time. There is no obvious advantage of
progressive core drill holes, except perhaps making the cores lighter
and easier to remove.
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