Homeowner Forum / Construction / November 2006

I am in the process of remodelling our basement.  Our home is about 2
yrs old.  I did not think that I had a moisture problem, except that on
occasion, leaves would plug up the footing drain in a window well and
water would come in the window.  So I am going to address this issue
outside.  However, after reading many of the threads on this site, I am
wondering about other issues.

A little background.  I have a single-story home with a full basement
(about 2300 sq ft) with 9ft ceilings.  About 6-8 in of the foundation
walls are exposed on the outside.  The walls are poured and have a
spray-on coating on the outside.  I have 1 larger crack (2-3mm wide)
across the whole floor that has been there since it was poured, and I
have recently filled that in and painted waterproofing paint over it as
well as many of the other much smaller cracks.  There were some
hairline cracks in the walls stemming from two of the windows and I
have sealed them as well.  All of this was a precaution.  I have never
had moisture through any of these.

I keep a dehumidifier running to keep it at 60% humidity, and it runs
much of the year.  It can collect 45 pints in a couple days in the
summer at peak humid times.  I don't know if this is abnormal or not,
but there are no return vents on the 92% efficient furnace/AC in the
basement, and that could contribute.  Any thoughts would be appreciated
on this.

Here is the issue. We have a 12x20 area with carpet remnant layed over
6mil poly.  When we started moving things around to build the walls, I
noticed that the concrete under this sheeting is darker than the rest
of the floor.  After pulling a section back for a while, the color has
lightened.  There is no actual condensation under it, and it has been
in place for about 2 yrs.  After reading some messages and my DIY
books, I am somewhat concerned.

I have asked my builder about this, and he did not think there was any
problem.  The floor is 4 in thick concrete with pea gravel from the
bottom to the top of the footings and there is drainage tile around the
outside and inside perimeter of the footing leading to a sump pump.
The pump runs normally a few times a day, rain or shine.

Should I be concerned with this issue?  Do I need to waterproof the
whole floor to prevent moisture?  I can't imagine that there is that
much moisture under the floor with the drainage available under the
floor. Could something not be working properly?  Please help, as we are
in the process of framing, and don't want to go too much further if
there is something that needs addressing.