positive and negative relates to the pressure on the wall created by the
water, e.g.:

water trying to get into the building - positive pressure on the outside
face of the wall and negative pressure on the inside face of the wall.
Generally easier to waterproof on the positive side, during construction,
and negative pressure after construction is complete.

Also, the materials for positive side are simpler - tar, membranes, drainage
mat etc. Negative side generally relies on the integrity of the wall being
waterproofed - which often is weak due to long term "water infiltration".
Materials such as Xypex work on limited substrates in good condition. My
opinion in many situations is let the water in and then manage it.

Please note my direct phone and fax numbers have changed again

Eric Hammarberg
Associate Director of Preservation
Associate
LZA Technology
641 Avenue of the Americas
New York, NY 10011-2014
Telephone: 917.661.8160 (Direct)
Mobile: 917.439.3537
Fax: 917.661.8161 (Direct)
email:  [log in to unmask]


-----Original Message-----
From: John Callan [mailto:[log in to unmask]]
Sent: Saturday, August 17, 2002 11:33 PM
To: [log in to unmask]
Subject: Re: drainage


John,

I've known the term, "positive drainage", as in make the water flow away
from the building.  I assume "negative drainage" would mean to make the
water flow toward the building...or do describe that situation.
"Waterproofing"?  Got me.  That's something people who deal in new
buildings believe in.  Sort of like "maintenance free".

-jc

John Leeke wrote:

> Could someone explain "negative and positive waterproofing."
>
> J
>
> --
> To terminate puerile preservation prattling among pals and the
> uncoffee-ed, or to change your settings, go to:
> <http://maelstrom.stjohns.edu/archives/bullamanka-pinheads.html>

--
To terminate puerile preservation prattling among pals and the
uncoffee-ed, or to change your settings, go to:
<http://maelstrom.stjohns.edu/archives/bullamanka-pinheads.html>