Basement Waterproofing Basics

Is basement waterproofing a do-it-yourself project, or does one need a professional contractor?

This depends on how much time, money and effort you are willing to spend. Frequent flooding, severe cracks that seem to be getting worse, bulging walls, and heaving floors are not usually do-it-yourself projects. If you hire an outside contractor do some research beforehand to find one that offers quality work at a reasonable price. In addition to being bonded and insured, be sure the chosen contractor offer a long-term warranty for -- this is quite important, even if it's initially more expensive.
Professional waterproofing systems differ, but most include one or a combination of the three approaches.
An interior drain field requires breaking through the basement floor, digging down to the footings, and installing a second drain field.

An interior drain field works in much the same way as the channeling system except that it runs under the floor. The installer excavates around the basement slab's perimeter, drills weep holes at the base of the walls, then lays perforated drainpipe in a bed of gravel. The result is a drain field like the one outside the footing. The pipe channels water to either a storm sewer or a sump pump.
An interior drain field is more costly than a channeling system, but its advantage is that it can handle far more water. This is an important consideration if your basement suffers from a high water table, a clogged exterior drain field, or heavy seepage.

If a spring or high water table is forcing water up from below the slab, it's recommend that you install a sump pump. A sump is a pit that collects underground or runoff water. As the pit fills, a float activates the motor of a pump in the pit. A one-way check valve ensures that water from outside won't back up into the sump. A sump pump turns on automatically as its pit begins to fill with water. It should come with a warning device that signals when the pump isn't working.

Excavating to the footing, coating the foundation or adding a vapor-retarding membrane, and installing a new footing drain is the most costly alternative, but it may be necessary if damage is extensive and the wall also needs to be rebuilt. Exterior damp-proofing is a last resort. Treatment may be roll-on or sprayed in compounds, sheet membrane, or other measures

Most problems unique to basements are caused by water. The first step in drying out a wet basement is to determine where the water is coming from. Is it condensation? Is water seeping in from outside, or trickling through a crack in a wall or the floor? Is a high water table trying to push the basement out of the ground? As you look at each of these problems, remember that the problem could be the result of a combination of issues.

Condensation results from excess humidity, often from an internal source such as a washing machine, unvented dryer, or basement shower. It forms where warm moist air comes in contact with a significantly cooler surface, such as an exterior wall or a cold water pipe.

If moisture is collecting on the floor or on one wall near the floor, it's probably seeping in from outside or up from under the floor. Seepage usually occurs because water is forcing through an expansion joint or through pores and hairline cracks in the foundation.

Often you can see water trickling down a basement wall or oozing up through a crack in the floor. Most basement leaks result from poor drainage, especially roof runoff, or a grading problem, aggravated by cracks that result from the normal settling of the structure. Walls that are extensively cracked need professional attention.

One of the most troublesome causes of a chronically damp basement is a spring or high water table that pushes water up through the floor under high pressure. This often shows up as a thin, almost imperceptible film. An underground water problem may require professional help.

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