In our wet Oregon climate water issues in basements or crawlspaces are common. One inch of rain on a 1000 square foot roof will result in over 600 gallons of water! If this water is n’t directed away from your house, it will find its way into the basement or crawlspace area.
Water in the basement or crawlspace can be more than just an inconvenience. Excessive moisture can lead to serious problems such as rot damage, insect damage, or mold. In some cases, water can impact the foundation or settlement to the house.
The first steps in keeping water away from your house are ensuring that gutters and downspouts are functioning properly and that the slope of the soil surrounding the house is sufficient to keep water away. Gutters need to be free of debris and they need to slope towards the downspouts. If your gutters are leaking or pulling away from the house water will be collecting near the foundation.
Downspouts should be directing water away from the house. If your downspouts are connected to drain pipes which head underground you may need to do some research to determine where these pipes are draining (see side bar). In older homes these pipes were often connected to the city sewer system but they could also go to a drywell or other on site drain. Older underground drain pipes may be in poor condition and water can leak from them at the foundation area.
If the grade around your house slopes away from the foundation, directing the downspouts to the surface and draining the water away from the foundation area is a good option. It is very important to make sure this water is draining away from the foundation and not collecting near the house.
The soil around your house also needs to be sloping away from the foundation area. If you have areas of your property which slope towards the house you may need to install drainage pipes or make corrections to the grade. These changes can be complicated and consulting with a drainage contractor is recommended.
Where do your drain pipes go?
The first step in researching where sub surface rain drain pipes drain to is your local building department. Try to obtain copies of the original building department permits and or plans. Often an old diagram of the plumbing system will be included and may show where the drain pipes go. Abbreviations you may encounter may include RD for rain drain and DW for drywell. In Portland you can obtain permit information by contacting Bureau of Development Services at 503-823-7300.