Technological advances in recent years now allow most modern basements to be made into comfortable living space. However, all basements are vulnerable to some water penetration during their lifespan.
Drainage tile, damp-proofing and moisture barriers all assist in preventing moisture from entering the structure through the foundation walls. Even with all these in place, if the area experiences an unusually high level of precipitation and the ground becomes saturated with water, the tile system may not be able to handle the volume and the hydro-static pressure that builds up along the foundation wall may force some of the water through hairline cracks and/or pores in the foundation walls. Older homes that may not have the advantages of modern technology and those that have more porous types of foundations (block, brick, stone) may be even more vulnerable.
Much of this can be prevented by ensuring proper eves troughs and down spout systems, and by ensuring the slope or grade of the lot is directed downwards away from the structure. In most cases you will be able to spot previous moisture or water penetration, however it is possible that a basement which has not leaked in the past may in the future if the conditions for leakage occur.
Another potential source for water in a basement is from a drain backing up. This type of situation is generally unpredictable unless there is evidence of a previous occurance. Indications of potential problems are homes in older areas of a town or city, where the municipal system is smaller and where the home owners' drains may be somewhat restricted by soil, tree roots, or accumulation of debris. Large deciduous type trees located in the path of a drain system should be considered as a potential problem.
Although a backed-up drain may appear to be a serious problem, the inconvenience of water coming into the basement can typically be prevented by the simple installation of a device called a backflow preventer or check valve. This device allows water to flow down the drain, but will not allow it to back up. Drains that have completely collapsed or are seriously blocked or deteriorated may need to be excavated and replaced.
If you do have water in your basement, I suggest that you research the circumstances thoroughly and have an unbiased professional diagnose the situation before taking any remedial action or beginning any work.
DID YOU KNOW?
Did you know that basement leaks are the number-one major complaint from new home owners? According to Ontario New Home Warranty Program (TARION) statistics, the average basement develops two leaks in the first two years after completion. The notable areas are cracks, form tie holes, and honeycombing.
In this day and age, we regard a dry basement as a reasonable expectation, but unfortunately, practice doesn't always follow design. Building a dry basement requires an effective drainage system and wall assemblies that are more or less water resistant. Now, what's under and around your house, barring any great re-constructive projects, is likely there to stay. So, the only realistic and cost-effective means of control that we have as homeowners (especially in older homes, without drainage systems) is to control run-off from on and around the house.
What's surprising, is that something as innocuous-looking as a low-lying flower bed can often be the major contributor to a wet-basement problem. Take a long, hard look around the house. Are the eves all fitted with eves troughs, and do the troughs drain freely into downspouts and discharge at least two meters away from the house? Has the back fill around the foundation settled? Any other low-lying areas? Watch where the water goes during a rain storm, or spring melt. If water drains from the street or other areas, towards your house, consider landscaping features which can guide the water away.
Different types of water ingress:
PERSISTENT: Occurring frequently throughout the year. Persistent leakage will almost always leave noticeable signs and clues, whether the basement is finished or not. Look for staining on the first 6-12 inches up from the slab, bubbling or peeling paint, effluorescence (white salts), damp musty smells.
SEASONAL: Generally occurring only at time of peak rainfall or other surface run-off, usually in the spring or fall. Seasonal leakage is more difficult to identify unless the leak is actively occurring. Look for stains on finished surfaces or stored items, rust on the bottom of appliances, raised storage.
ONE-TIME ONLY: Occurring only when very specific conditions exist. This type of leak may occur once in the life of the basement, or may occur every few years when the appropriate conditions exist. One-time leaks (somewhat of a misnomer as they can, and frequently do, occur more than once) are the hardest to identify, again unless an active leak is occurring at the time of observation.
Visit www.aquafixontario.com for more information about wet basement solutions.
Gil Strachan is a professional home inspector, representing Electrospec Home Inspection Services in east-central Ontario since 1994.