Basement flood confirms trickle down theory
by Roger Faris
During our wet season I get many calls about basement water problems. People are often quite upset. They are desperate for quick and permanent solutions. I ask questions about possible sources of the water, and then describe typical remedies. Sometimes I'm asked to come over for a "house call", which gives me an opportunity for real detective work and a more educated guess at the best cure. Over the years I have gained some skill and confidence. I've collected a lot of facts and figures, and feel prepared to fight the battle. Looking way back, though, I remember having a different perspective.
Once upon a time I believed that water in the basement could be a very good thing. I was a young boy, and my parents went out on some errand. I was left at home with a brother whose adventuresome ideas were a perfect complement to my own. We decided to turn the basement into a swimming pool. The vision was perfect and pure: we'd be able to walk part way down the stairs and then just dive into the water. Why hadn't the rest of the family ever thought of it? We got started right away, putting a plug in the laundry tub drain and turning the faucet handles to full blast. When water began to spill over the top, we found a way to seal the floor drain. Everything was going just fine. Before long an inch of water covered the basement floor. This was perfect for skating and sliding along, but eventually we noticed that water was escaping under the garage door. Before we could solve that problem, our parents arrived on the scene, bringing complications of another sort.
The cause of our basement flood was not typical. The most common source of water in a basement or crawlspace is the discharge from gutters and downspouts during a heavy rainfall. The roof drainage may be connected to the sewer system, but too often the underground pipes are clogged with sand and other debris. If these can be successfully cleaned out, the basement water problem usually disappears. In many other cases water is being discharged right next to the foundation, or diverted about two feet away by a splashblock. Sending this water to a drainage field that is located further away from the house is usually an effective solution.
A more unusual, but still troublesome source is rainwater which flows along or near the surface of the ground until it encounters an unprotected basement wall. The water can sometimes be diverted by a surface drainage system which leads it to another part of the property. This can be a simple ditch with perforated plastic drainpipe surrounded by gravel. Regrading of the yard to slope away from the house could also be effective, but this is practical in only a few situations.
Rainwater sometimes descends below the surface of the yard until it encounters a layer of clay. It may then travel horizontally until it reaches your basement wall. This can present a tricky situation. Capturing and rerouting this water can require a lot of digging. It's a good idea to make a test hole in the yard to see what kinds of soil strata are present, and at what depth.
Some basement water problems involve only minor seepage. People with this situation can often get good results with products for interior patching and and sealing of concrete. In an unfinished basement this is usually an easy and inexpensive experiment, and therefore worth trying. Consult your local hardware store or a masonry materials supplier for recommendations of best products.
The worst basement water problems involve ground water. After several days of heavy rainfall the local water table might rise to a level which is higher than your basement. It can be pretty dramatic. One time I was invited to take a few steps down a basement stairway to see what one new homeowner was facing. The water was several feet deep, and quite clean. I put my hand in to confirm that it was too cold for swimming.
Basement waterproofing specialty contractors are often called in when people face a major problem. The different companies use a wide variety of approaches. Sometimes an interior perimeter drainage system will do the job. An electric jackhammer is used to remove a portion of the concrete floor in the basement, allowing installation of perforated pipe in a shallow ditch. This collects ground water and sends it to the sewer or to a sump pump and drainfield arrangement. The pipe is surrounded by gravel, and the floor is patched.
High pressure injection of clay or a silicone gel is another method which can sometimes keep the water out. A powerful pump, usually mounted on a trailer, is used to send the grout through a heavy hose and metal probe. If all goes well, it can provide a waterproof seal on the outside of walls and below a basement floor. If all doesn't go well, the injected material may find its way through a crack in some important drainpipe, or the clever and resourceful ground water may discover a way around or through the material.
The best remedy for ground water problems, unfortunately, is the one which involves the hardest work. Most engineers recommend excavation around the outside of the house down to the level of the concrete footing under the foundation walls. This permits the installation of a new perforated pipe drainage system, application a waterproof coating to the outside of the walls, and filling the trench with gravel. The difficulties include the amount of digging that must be done, what to do with all the surplus dirt, and dealing with obstacles such as trees, shrubs, sidewalks, driveways, retaining walls, and the like. People who have been through this wish that in the interest of fairness, everyone else should have the same experience. A note of caution: If you dig a deep trench around your house, take care to brace the sides with plywood and lumber. Premature burial can be fatal.
|
