Expert: Richard Taylor, AIA - 7/12/2007

Question
QUESTION: We have an old house with an old musty humid moldy cement basement. I'd like to have one of those plastic sealants applied, but I was told those have to go on the outside when the cement is poured.  Would putting that down now invite a buildup of moisture in the foundation that's worse than we have already?  (We're surrounded by serious wet clay all the time.)  We don't get flooding unless there's a pipe leak (old houses get those) but it would be nice to have a laundry room and a place to put file cabinets and even maybe a computer.  I'd like a shiny white plastic clean looking surface.  But I don't want to destroy the house and I'm worried about this.

ANSWER: Hi Louis - thanks for your question!

You're right, applying a water barrier to the inside of the wall does little good, and can do a lot of damage.  First you need to address the cause(s) of the water infiltration.

The most common source of basement moisture is disconnected or blocked downspouts - check to be sure they're all clear and are draining water away from the foundation.

The second most common cause is soil that slopes towards the foundation instead of away (easily fixed), and the third is groundwater (not always easily fixed).

Correct all the causes of outside water getting inside first - even if that means excavating around the foundation and installing a drain tile - or all the time and money you spend improving the interior will be wasted.

But before you do anything like that, put a big dehumidifier in the basement and run it full-time for a couple of weeks.  That will tell you something about how serious a water problem you have.  Most old home basements should have a dehumidifier running full-time anyway.

Once you're sure you've addressed all the water problems you can begin finish off parts of the basement.

Hope this helps!

Richard Taylor, AIA
www.rtastudio.com
www.rtaplans.com

---------- FOLLOW-UP ----------

QUESTION: Sorry but I am new to this - what exactly is a drain tile?

Do I assume 'excavating' means digging up all the soil around the outside, this means going all the way down to the bottom of the foundation? (est 10 feet or so? because that's my basement depth to the ceiling.)

Answer
Louis - yes, the drain tile is at the bottom of the wall - it's a big job to replace or install one in an existing home.

Drain tile is a semi-porous cylindrical tube that runs around the outside (and in newer homes, the inside also) of the foundation wall.  Its job is to channel water away from the wall, usually to a sump pump but sometimes down to a ravine or other lower area if the house is on elevated land.

Old drain tiles were made of clay tile sections; newer ones are ABS plastic - they're the black corrugated pipe you see at Lowes or Home Depot.

Hope this helps!

Richard Taylor, AIA
www.rtastudio.com
www.rtaplans.com