If you are living in the Portland, Oregon and Vancouver, Washington area, you already know that we get a lot of rain. For most of the year, it pounds our homes with moisture and many home are equipped to handle this much water, but some are not. Many houses in the Portland Metro area have inadequate gutter drains or just retain ground water that accumulates underneath the home in the crawlspace. Water in the crawlspace can become a big problem later on. If left untreated, it can lead to mold, rotting structural supports and many other issues. So, let’s suppose that you have a crawl space that has standing water and discuss what a typical drainage solution will likely consist of.
Ground water works its way up through the soil as the water table rises and can begin accumulating underneath your home. To solve this, a trenching system or “french drain” needs to be installed to direct water to a discharge point (sump pump or low point drain, which we will get to next). A drainage contractor installs this by first removing the existing vapor barrier (plastic covering the soil in your crawlspace) and then digging a trench that is sloped toward the discharge point. The trench itself is a minimum of 6 inches deep and 4 inches wide. Once the trench is dug, a base layer of rock with be added to the bottom of the trench, then filter fabric will be placed underneath a 3 to 4 inch perforated drainage pipe. Once fabric and pipe are in place, we will cover it all with another layer of drain rock. This completes the trenching and french drain.
Sump Pump or Low Point Drain
Getting the water out is the most vital component and can be done in a couple of different ways. Gravity is your friend here and you would want your discharge point to be at the lowest point of your crawlspace. Your french drain will get the water to the discharge point because the trench is sloped towards this area. The first and simplest option is usually a low point drain. Most homes have a low point drain which is just a pipe underneath the home that sends water outside (typically attached to the underground gutter drain system). If a low point drain exists, the french drain can be tied directly into it ONLY if the low point drain is low enough. Many times the low point drain is a builder afterthought and it is not low enough to allow gravity to get the water flowing out of the crawlspace. The next best option is the installation of a sump pump.
To install a sump pump, a basin first needs to be put in. A sump pump basin is going to be about 22 inches deep with a diameter of about 18 inches and will need to be installed so that the top of the basin is flush with the ground level. Before putting the basin into the ground, 1/4 inch holes are drilled in to allow water to flow in and the basin is surrounded by drain rock. Next, the pump itself is placed on the bottom of the basin and plumbed to discharge out of the space. This pipe generally will go out the foundation vent screen, then go underground into the 3 inch gutter drain pipes that typically run around the perimeter of the home. If no underground drain pipes are present, the water may have to discharge into a drywell or other collection point that is away from the home.
Those are just the basics for installing a drainage system for homes in the Portland, Oregon and Vancouver, Washington area. For more information on the services that drainage contractors offer, please give New Leaf Crawl Space Solutions a call today.