Today, knowing about different home systems and various inspection problems are important tools for real estate practitioners. In fact, recognizing the need for certain repairs/improvements can increase the marketability of a home to potential purchasers.
And then there are those repairs that absolutely must be completed in order to sell a home to any buyer. A leaky basement can be classified as a necessary repair and this problem can be easily corrected.
Most wet basement problems can be solved fairly easily and without huge expense. The vast majority of wet basements result from surface water, (from rain and melting snow), rather than ground water. Therefore, proper grading and good eaves troughs and down spouts are essential.
Houses are not boats! If the ground around the house gets saturated, eventually the basement will leak. You can spend a lot of time and money trying to make basement walls waterproof, but it is much easier to make the water run away from the house. Slope the landscaping so that it drops away from the house at least six inches in the first six feet.
Having this slope is particularly important during the Spring thaw because the ground is still frozen. If the land slopes back toward the house, all the water will run across the surfaced, (because frozen ground won't absorb any) until it reaches the foundation wall. The ground adjacent to the house isn't frozen, due to the heat loss from the basement, so all of the water ends up against the foundation wall, where it eventually finds its way inside.
The water that lands on the roof will also end up in the basement if the eavestroughs are leaking or overflowing. Even if the eavestroughs are in good shape, the basement will be wet if the downspouts dump all of the water beside the foundation walls. Downspouts should have extensions that discharge the water at least six feet away.
If a downspout goes into the ground, it must discharge into a functional drain. Often, the below the ground portion is cracked or broken. It can be dug up and repaired, however, it is far less expensive and much easier to cap the drain and divert the downspout onto the lawn.
In many older homes the drains from the downspouts travel under the basement floor and connect to basement floor drains. They tie into the drain above the trap. Therefore, all the leaves, twigs, maple keys, acorns, etc., end up in the trap and a heavy rain will cause the floor drain to backup. This often is misdiagnosed as sewer backup. Many a front lawn have been dug up and drains replaced, when all that was required was to clean the floor drain trap. Better yet, disconnect the downspout from the drain and discharge it onto the lawn.
Even houses with good surface water control will experience leaks if the foundation walls are cracked or have voids. Many new houses experience minor shrinkage cracks and/or settling cracks in the foundation walls. These are best patched from the exterior.
After the crack has been filled and the damp proofing repaired, the patch should be covered with material specially designed to be free draining. These materials allow water to flow through them. Once into the material, water drains to the bottom, and into the drainage tile. (This material works like a bundle of drinking straws all standing on end).
Sometimes, digging and damp proofing of foundation walls are necessary. But, because it is so costly and disruptive, it should be considered a last resort. Try the inexpensive approach first. Make the water drain away from the basement walls rather than attempting to make your walls water tight.
P.S. – Ever notice how waterproofing contractors always improve the grading when they are backfilling after their foundation work? It makes you wonder.