In many old houses drying out the basement or crawl space can be a major undertaking. Basements have their share of other problems, too, including frozen pipes, various pests, such as termites, and radon gas.
Protecting Your Basement Against the Cold
Depending on the severity of your winters, you may need to give attention to freeze-proofing your basement. In the list below, the very first measure should be sufficient in southern climates, but the further north you live, the more of the list applies.
• See that all air vents close tightly.
• Find and seal all leaks in the foundation with mortar, caulking, and stuffed-in insulation.
• Avoid under-floor insulation, if possible: House heat that filters down can help keep the basement above freezing.
• Glaze any loose windows the basement may have.
• Install a small space heater to use during particularly frigid weather.
• Use rigid foam sheathing to insulate outside walls near pipes. I don't recommend insulating the pipes themselves, because should an insulated pipe become frozen, it will take forever and a day to thaw out, unless you use the new thermally-activated heat tapes, which can be used inside insulation on individual pipes.
Wet basements are bad for the house and unpleasant for the people who live in the house.
Install a drainage system inside the basement. Often the water in the soil around the house will force itself down under the basement and up around the edges of the floor. See below for suggestions for laying drain tile and /or installing a sump pump.
Avoid letting water settle along the base of foundations or posts or it will eventually undermine them. Repair by pointing or plastering where past water problems may have damaged the foundation or posts. If bricks in a foundation pier are severely deteriorated, build a form and pour concrete around the offending portion (which usually will be at the bottom where there is the greatest moisture).
Groundwater control is essential. It isn't sufficient to deal with water in the basement merely by providing drains and a sump pump or even by having runoff drains where the lay of the ground makes this possible. You must stop water from running into your basement if at all possible: It is bad for your foundations, and the basement will remain damp even if it's channeled and controlled by a drainage system. Get serious, therefore, about controlling the groundwater running into your basement. There are at least three approaches to your problem:
• First, redirect the water, before it runs into the basement, by changing the water runoff to keep it away from the house. This can be accomplished by adding gutters to the roof and by installing drain lines for downspouts.
• Better still, pour concrete slabs along the foundations and extending 2 to 3 feet out from the foundations, tapering way from the building.
• Best of all, install exterior foundation drains. The material cost of these is relatively low, and far less than concrete slabs, but the labor is considerable. Make it easier on yourself by doing just one side of the house at a time. Here’s how it’s done:
1. Dig the ditch at least 3 feet wide, with the surface sloping toward the low side of your property where the drains will carry off the water. Be careful not to dig so far as to undermine the foundation of part or all of the wall: for houses with basements about 1 foot should be fine. Make sure the bottom of the ditch slopes away from the house at least 1/4 inch to the foot, with no dips or hills in it. You want a steady slope so water will not stand in the drains.
2. Lay down a continuous sheet of heavy polyethylene, tacking one side of it to the foundation at a point higher than the original ground level.
3. Install slotted plastic drainpipe along the edge of the foundation. It comes in 10- and 50-foot sections with elbows, Ts, and connectors to make installation easy.
4. Attach an un-slotted drainpipe to the lowest end of the foundation drain and route it 4 feet or more away from the house to a location where ground slope will carry the water away from the house.
5. Cover the slotted pipe with coarse gravel, then cover the gravel with a soil separator such as a weed-control fabric that will let water through but keep soil from washing into the gravel and plugging it. Replace the dirt. Try to slope the ground away from the house.
Pests and Plagues in Your Basement
Termites aren't merely a basement problem, of course. If you don’t do something about them, they will be a whole-house problem. They get their start in the basement or crawl space, however, since they originate in the ground and move up to feast on your delicious house.
Some Words of Wisdom and Caution About Termites
There are three things that termites really like in a home:
• The dark of your basement
• The moisture of your basement
• Much decaying wood that touches the ground
Termite damage isn't necessarily a sign that your house is a lost cause, but termites must be stopped before they do damage the whole house irremediably.
Treatment does not mean tearing into the walls and searching for termites. It is enough to cut them off at their supply lines. Consequently, treatment consists in flowing a long-term, residual pesticide around the edges of everything that connects the house with the dirt. Because the pesticides used for this treatment are quite powerful, treatment is most often done by professionals. (Chlordane, which was the time-honored chemical for killing termites, was found to be a carcinogen and has been banned.) The technique used involves digging trenches along the foundations and posts, which then are flooded with the solution. Hollow masonry walls are drilled and the liquid is pumped in. If you have a well near the house, however, insect control professionals will not perform this treatment for fear of a contamination suit.
Reconstruction After Termites
Hopefully, the doubling of termite-damaged joists or wall studs will be adequate repair. Use pressure-treated lumber to avoid future problems with either termites or rot. In areas devastated by termites, however, it's best to tear out and rebuild. In the long run, you will probably save labor and materials by so doing.
The Newest Scourge: Radon Gas
This is the latest scare for all house owners, not just owners of old houses. It isn't the kind of problem that's a threat to you today or tomorrow, but one that you would not want to live with over a number of years. You can test your basement with readily avail able, relatively low-cost kits. It is best to test your house in the winter, when the basement area and the house itself aren't ventilated and the readings are thus highest.
The geological characteristics of your area are the most important factors determining whether or not you have a radon gas problem. Rock or shale seems to allow the gas to migrate more readily than it does in areas with damp clay. Other contributing factors are
• Lack of ventilation in the basement or crawl space
• Lack of ventilation in the house itself (actually less likely in old houses than in new)
Various authorities recommend different methods of treatment for radon gas problems. The following advice is commonly accepted:
• Seal all cracks in masonry-walled and concrete-floored basements with caulk—usually a tough problem in old houses. Seal the traps in all floor drains, then use a small fan in the area to put a slight pressure on the drains. This keeps all drain areas flushed with fresh air and keeps gas from building up in them.
• Ventilate the basement to the outside.
• Eliminate all holes where air could get up into the main structure of the house from the dirt area.
• If possible, use polyethylene to cover the dirt in an unfinished basement or crawl space or the underside of the floor.
• After treatment, use another test kit to monitor improvement.