Banty wrote:
In article , Jim Elbrecht says...
On 2 Apr 2008 04:50:04 -0700, Banty wrote:

In article ,
aemeijers says...
I still say water should be redirected or stopped outside the basement
perimeter. If that can't be done without heroic measures, well, maybe
that was a bad place to put a house/basement. (
It's never been explained here that I've seen - exactly **why** is an exterior
perimeter drain preferable to an interior tile drain??
I can think of 2 reasons offhand-[from personal experience]- lower
humidity in the basement, and less chance of filling the block up with
water & 'rotting' them.

Jim

What exactly do you mean by 'rotting' the concrete block?

Interior french drain systems usually include a way to drain the bottom blocks
of water, if any, to redirect along with water in the trench.

Banty

If there is water in the block, that means the wall is always damp, even
when it 'feels' dry. Concrete is not waterproof- that is what you see
when that white haze (efflorescence?) shows up near leaks- the white
stuff is minerals the water leached out of the concrete and mortar,
thereby weakening it. Doing construction demo as a kid, you could always
tell walls that had been wet long-term- you could pop the bricks or
blocks apart with just a tap. It eats away at the mortar first, and then
at the concrete itself.

And when you have water exposed to the heated air of the basement, even
if hidden under the trim covering the slit trench along the wall, that
can't help but spike the humidity down there. Even when I don't have
visible leaks in summer, I have to empty the dehumidifier every 2nd day.
(Sure wish the floor drains hadn't rusted/teakettled shut...:^( ) My
sump pit has been bone-dry since I have lived here- it is surface water
coming down through the backfill and failed waterproofing, migrating
through the walls. I'm convinced replacing the outside drains (assuming
they are there at all) and redoing the waterproofing would fix the
problem, but since the basement doesn't actually flood, it would
probably be a money loser at resale time. (Trust me to buy a house right
when the 5-7 % a year appreciation in housing values stops dead in its
tracks. Value of this place is MAYBE going up at the rate of inflation.)

Interior drains beat a wet basement, but a waterproof basement envelope
is what you should strive for.

--
aem sends...