On Thu, 14 May 2020 11:52:31 -0700 (PDT), S N
wrote:


I am currently digging out my basement and installing
a french drain/perimeter drain system next to my footings.
My building was built in 1890 so it is built on a stone foundation
(accept the footings which are concrete).
Most advice/direction on perimeter drains are for newer homes
with concrete foundations or slabs. Does anyone here have
experience with a stone foundation? My footing is about 18 inches
below my basement floor.
Is it best to lay my pipe next to the footing or on top of the footing?
Either way it is still well below the floor.
How many drill holes should I drill through the foundation to make weep holes?
Would one every 12-18 inches suffice?
Where is it best to drill the holes- can I do it just above the footing
where it is a bit thinner? The walls are very thick- 18-24 inches thick
and the footings are even thicker.
Any advice is appreciated, thanks.


Hard to imagine _why_ you're doing this ?
Perhaps I'm not understanding the french drain concept ?
Did you consider a sump pit & sump pump -
with an above-grade outlet - which runs away
from the foundation ?
John T.


French / perimeter drains capture water that weeps in from your walls
and from hydrostatic pressure caused by changes in ground water levels
that push water below your basement floor. If these drains are installed correctly,
they reduce the pressure and lower the water table, resulting in a dry- usable basement.
The best way to do these is to install them outside your home- unfortunately,
I am in a dense city where our buildings are basically lot line to lot line.
So I have to dig it inside.
The drains all slope towards a sump pit with an above grade outlet.


OK - but it seems like you are inviting more water into your cellar
if you create new holes through the footing/foundation -
and therefore asking for a busier sump pump .. ?
John T.

Yes- that is the right way to do it- you don't want water pooling
around your foundation- it can cause spalling of your brick and concrete
as it soaks in and up. It can also lead to mold and other issues.
Its best to have it dry around your foundation.
I understand if you have never dealt with them it may seem odd
to do but its the only way to reduce exterior hydrostatic pressue
without installing a perimeter drain on the outside.


OK - thanks for the explanation.

If it was me - I would try to reduce the
"hydro-static pressure " ?
from the outside - before inviting it inside.
... landscape swales ; downspout helpers ;
neighbour's drainage ; etc.

I feel sure that you have already done that research.

Good luck.

John T.