fb-pixel Skip to main content

Prevent wet cellar walls and flooded lawns

Many times water in the basement is due to a lack of gutters
Many times water in the basement is due to a lack of gutterscourtesy Rob Robillard

Q. During heavy rainfall I get water coming into the basement where the concrete floor meets the walls. Also, the concrete in the walls appears to have some flaking. What are my best options to fix this?



A. Water in your basement can come from a lot of places. Many times it is due to a lack of gutters, improper ground sloping, clogged perimeter pipes, or hydrostatic pressure.

The first thing to check is the grading around the house and the gutters. Ensure that your gutters are not clogged and that they are draining well away from your foundation walls; 10 feet is my preference. Most folks I know do not like downspouts extending out far. If there is pavement in this area, make sure it slopes away. Correct it if it does not.


If you do not have gutters, consider getting them.

It's important to make sure the ground slopes away from the foundation ½-inch per foot, or 5 inches over a 10-foot distance. If the property lines are too close, consider increasing this slope and using swales or underground drain piping.

A swale can easily solve standing water, flooding, and yard-drainage problems. A swale is simply a shallow ditch that is used to carry off water and relies on gravity (a slope) to drain. Swales are often wide and so shallow that you do not notice them in a lawn. I like them because they are maintenance- and electricity-free, with only one negative aspect. The longer a swale gets, the deeper it needs to be.

( TIP For proper drainage, I install swales 1 inch for every 10 feet of length.)

There's a large hill on my neighbor's property that funnels huge amounts of water into my yard when the ground is frozen. I was able to redirect the water by installing a swale and channeling it around my house to a drain basin.


You mentioned that water is seeping in where the wall and floor join; oftentimes that can mean hydrostatic water pressure is present. Assuming you have ruled out gutters, grading, and ground-water issues, the best approach to this problem is to install drainage underneath the floor slab that will empty into an integrated sump pump pit.

Many full-time basement waterproofing companies offer and install interior drainage channels with a special profile that includes a wall flange with spacers for collecting wall seepage, channel holes that allow ground water to enter the drain line, and a large-diameter channel that slopes to the sump pump pit.

Without having the benefit of a site visit, I would have only one conclusion for the foundation wall flaking. Assuming there are no major cracks or other defects visible, moisture intrusion from the soil outside your home is the likely cause of the damage. This issue is often referred to as "spalling." This moisture could be the result of the exterior ground sloping toward the house or excessive amounts of water flowing toward it, as was the case in my side yard prior to installing the swale.

Concrete that is not properly sealed will absorb moisture. Older homes with poured-concrete walls often had a tar coating applied, which is a damp-proofing (not a waterproofing) method. It also has a limited life expectancy of 30 years or so.

Water that enters concrete will eventually exit, causing spalling or leaving a white chalky power, called efflorescence, on the surface. Efflorescence forms as the water evaporates, leaving the salt behind. Usually this can be brushed off.


The real solution is to stop the water from getting into the concrete. Do this by reducing the amount of moisture in the soil by adding gutters, improving slope and drainage, or damp-proofing or waterproofing the outside of the foundation walls.

Carpenter's tip

Hands Free Leveling (1)

(The Boston Globe) Concord carpenter Rob Robillard gives readers a hands-free leveling tip.

On my website, I am always preaching about finding ways to work smarter and more efficiently. That means looking for and learning tips and techniques that will not only help you accomplish your job, but save you time and money.

If you are trying to install something and using a level to plumb an item, here is a simple tip to make your job easier:

You can make your level "hands free" by simply clamping it to the surface you are working on. I always joke that carpenters should have three hands when assembling and using levels. This tip is not new, but it's a good one and one I use often.

I prefer a pistol-grip clamp because it allows me to use one hand. I simply attach my level to the side of the object to be plumbed. The level stays in place during the installation and can be checked as needed.

Rob Robillard is a general contractor, carpenter, and editor of AConcordCarpenter.com and principal of a carpentry and renovation business. Send your questions to homerepair@globe.com or tweet them to @globehomes or @robertrobillard.