If you are like me and live in an older home, you may have issues with a leaky basement. As we head into the wettest months for Pennsylvania as identified by US Climate Data.com, I have been thinking about my sources of water and how I might best remedy these issues. A quick search online lead me to two articles, Wet Basements by Albert Jerrett, PH.D. and How-Water-Gets-Into-Your-Basement by Kevin Bralser, that I found informative. Since my source of water occurs during the high watertable season and storm events, my focus is on surface waters and ground water sources.
In Pennsylvania, average annual precipitation ranges from 37 inches to more than 45 inches per year, according to PA’s BMP Manual, which used data from the early 2000’s. It is important to understand the volume of water that runs off your roof and towards your foundation because this water must go somewhere. Both articles discuss that surface water enters the basement along the foundation walls and summarize here, due to poorly graded lawns exacerbated by poorly installed landscaping and poorly installed downspouts.
To solve surface runoff issues, redirect the runoff.
In new residential development, I grade two to five percent for the first five feet from the foundation walls and a max of ten percent for the next ten feet. I direct all runoff around the foundation to storm drains in the public right-of-way by local swales, keeping them a minimum fifteen feet away from the foundation when possible.
For existing homes, if regrading your site is not feasible, I suggest installing yard inlets, surface trenches or some other structure that will capture the surface runoff and allow you to redirect it underground. You will have to evaluate which solution is appropriate.
In both new or existing homes, confirm that your roof gutters are properly installed and directing runoff at least five feet away from your home. You can purchase various piping and connections from your local hardware store to achieve this. In most cases a standard four inch pvc pipe will be sufficient to handle the discharge from your downspout. For larger homes or homes where you wish to connect multiple downspouts to a single roof leader, consult a professional to ensure that your pipes are appropriately sized.
At our recent Warehaus ‘Sharehaus’ lunch-n-learn, the George Spangler Farm project was presented studio-wide. I particularly was interested in the anecdote regarding the basement remediation. A spring was discovered along a basement wall.
Though you will typically only find these situations in historic homes that have been built around well houses, springs may be a source of your leaky basement. If your home was constructed along the toe of a slope, there is the potential to experience groundwater influence from a spring.
If your source of a leaky basement is due to a high watertable or a spring, you will have to install a drain either inside or outside the foundation wall and direct the groundwater away from your foundation.
In most cases, it is impracticable to daylight the drain within the boundaries of your site. In these cases, you will have to include a pump in your design, to lift the groundwater from the elevation below your basement floor to an elevation that will allow you to daylight the drain within your site boundary.
Assess your source of leaky basement using the references provided here or from your own research. From that research, try some small economic solutions first and incrementally increase solutions as needed until a solution is found.
If you can’t find a solution on your own or don’t feel comfortable with a self-evaluation, find a professional to provide you with alternatives.
With Warehaus’ team of expert architects and engineers, we would be pleased to help you find a solution to your issues.