Gutters and Downspouts
These are the single biggest cause of wet and damp foundations for most homes. Missing extensions, poor grading, and soil erosion are the most common items I continually find during home inspections. Most home owners are unaware of the sheer volume of water that can be directed down the side of their basement foundation by these minor little problems.
The average roof will collect just under 5,000 Gallons or 18,000 Liters, this water is directed to your downspouts to ground level. As you can see if your surface water is not directed away from your home, is it any wonder there are problems with damp or wet basements.
Some people have started collecting the roof water and utilize it for water gardening and lawn watering.
Common Problems for Gutters
Missing - Can cause dampness in basement, deterioration to cladding and damage to landscaping
Undersized - Likely to clog with twigs and leaves, water can overshoot undersized gutters
Leaking - Check at seams, end caps and any change of direction
Loose - Will allow water to run behind gutter which can damage soffit, fascia, wall systems and foundations
Damaged - Look for evidence of mechanical damage, from ladders, trees or forces of nature
Clogged - Usually at downspouts and is usually the result of lack of maintenance
Improper Slope
- Typical drop of one inch over the run of 17 feet is normal
Downspouts
Downspouts typically have the same problems as gutter except the added concern of where they discharge to. A missing downspout is more serious than a missing gutter because the water is more concentrated at the downspout area and all the water is directed towards foundation and may cause considerable damage to walls etc.
Upper roof gutters with missing downspouts can cause considerable damage to lower roofs if allowed to fall directly onto shingles. This will definately lead to early shingle failure and should be an item of concern for the homeowner.
The number of downspouts can be roughly calculated at one downspout for every 35 feet of gutter length. The ideal place for downspouts to discharge is 6 feet from building and the ideal slope is an inch per foot for proper drainage.
Underground drains are common and are more pleasing to the eye than a six foot piece of downspout extension laying across your lawn. The disadvantages are that they can stop functioning for quite some time before the homeowner is made aware. The ground can become saturated causing dampness through foundation walls etc.
Personally, with our Canadian climate I always recommend adding a Tee above entry into drainage tile. This allows water to drain away even if drainage line freezes.