Hi Dan,

Is your basement cement block? If so, probably breeze block.

The thing about waterproofing cement is that you need to create a continuous 
waterproof membrane. It is best on the outside. Cement and mortar is porous. It 
transmits water. Actually capillary action will draw water through it from 
areas of higher concentration to areas of lower. Additionally, hydraulic 
pressure will accelerate osmotic pressure. You have already figured out what 
happens when water lies against a concrete wall. It will even wick up through a 
concrete floor which is why laying boards on concrete will result in damp 
unless the soil under the floor is very dry. Plastic, like a poly bag will very 
often condense moisture on it's underside when laying on an otherwise 
apparently dry concrete floor.

To truly dry a basement you must either provide an easier path for water to 
escape than through your walls or deflect it away from the basement altogether 
or provide a continuous vapour barrier preferably on the outside so moisture is 
unable to collect on the back side of the barrier or all three. Hydraulic 
pressure under a basement floor is often responsible for lifting paint.

People up here slather tar all over block and poured basement walls but sooner 
or later it develops cracks and water will then penetrate. It does not require 
a crack and plugging a crack may only slow the water.

Water will ultimately leach the lime out of mortar. sometimes Portland cement 
is added to mortar which will slow that process but it hardens and stiffens the 
mortar and reduces it's pliability.

Unless you are willing to excavate all around the exterior walls and provide 
crushed rock and weeping tile and apply a really good membrane you might as 
well accept that moisture will appear under certain conditions.

There is now a form of glass fiber board which is woven to shed water away from 
the foundation though I couldn't find it when I was looking several years ago.

Block walls will often collect water within the cavities. this will more 
happily drain into the house than back out into the damper soil outside.

Pardging or otherwise treating the inside of a basement wall against moisture 
never succeeds for very long unless the exterior circumstances are fixed.



  ----- Original Message ----- 
  From: Dan Rossi 
  To: [email protected] 
  Sent: Tuesday, July 22, 2008 11:16 AM
  Subject: Re: [BlindHandyMan] Tuck Pointing?


  RJ,

  thanks. I am just curious as I've noticed some rotting mortar joints in 
  my basement. I had the entire outside of the house pointed last year, and 
  am now considering what to do, if anything, about the foundation.

  We were getting a bit of water seepage in one area of the basement, but I 
  figured out that the problem was that one of our down spouts had blocked 
  up and water was jetting out of the side of it and had washed away a bunch 
  of dirt right against the house. I fixed that and the seepage has 
  stopped. I guess I will type more about that little project under 
  separate heading.

  Thanks.

  -- 
  Blue skies.
  Dan Rossi
  Carnegie Mellon University.
  E-Mail: [EMAIL PROTECTED]
  Tel: (412) 268-9081


   


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