 An Inspection Question:
What can I do about basement moisture
problems?
Q: How can I determine whether the
basement leaks?
A: Sooner or later, most basements in damp
areas leak to some extent. Leaks may be seasonal or may only appear when heavy rain
conditions have existed for some time. First check any penetration at or below grade:
window wells and outside cellar stairwells frequently admit water. Look for cracks in the
wall or in the mortar joints between cinder blocks. Examine the bases of items stored in
the basement for water stains and rust. Other vulnerable spots are the joints between the
wall and floor, tie-rod holes, and at the bases of steel support posts. One sign that
there has been water seepage in the past is the presence of efflorescence, which
appears as a light-colored powdery deposit on the wall or floor. It is the result of
mineral salts, originally part of the concrete or masonry, dissolving in the water as it
migrates through, and remaining on the surface after the water evaporates.
Q: I have quite a bit of water
leaking through my basement wall in the rainy season. What can I do?
A: There are many possible contributing factors
when looking for a solution to basement leaks. A sensible strategy in my opinion would be
to address the easier and less expensive possibilities first and hope for improvement.
Here are some suggestions, listed from lesser to greater effort and expense:
- First, clean all gutters and be sure that water from downspouts is
directed at least ten feet (more is better) from the foundation wall with good quality
drainpipe. Use a garden hose to test existing underground gutter discharge drains.
- Remove excess vegetation next to the house.
- Remove large roots, which can channel water to the foundation.
- Seal all exterior asphalt or concrete driveways, decks, and steps
where they join the house.
- Fill the (accessible) voids where soil has settled under stoops and
slabs.
- Fix any hose sillcocks that drip.
- Install awnings over cellar stairwells.
- If there is no way to direct water away from the home’s
perimeter, it may be necessary to install a sump pump to collect and eject water.
- Redirect the water flowing from a slope above the house using a swale,
which is a gentle, shallow ditch. (See illustration below)
- Install a French (curtain) drain around the uphill perimeter of the
house to intercept and redirect sub-surface water before it reaches the foundation wall.
Q: Is there a way to seal out the water from the
inside?
A: Yes and no. No foundation wall can serve as
a dam - keeping out water that builds up high above it’s footings. There are several
products on the market that are sold to stop basement leaks by creating a seal on the
interior surface of the wall or floor. If the problem is very minor or occasional, they
may be effective in reducing moisture and attendant humidity in basement spaces. In my
opinion, though, they should not be used to try to contain a significant volume of water
infiltration. The reason is that when interior leak prevention efforts are successful, the
foundation wall can be damaged by excess water. Saturated walls can expand and be weakened
by freezing. It may cause spalling (surface deterioration) or weakening of mortar joints.
It may also cause the reinforcing steel to rust, and moisture may be wicked up into the
wood structure, possibly causing rot. It may cause increased condensation and humidity in
the room.In all, concentrating on good surface and subsurface drainage, and keeping the
water at a distance to begin with is much preferable to attempts at interior
"waterproofing". |
