Wet basement? Check your gutters!
Updated: Aug 1
I got a call yesterday from a client whose home we inspected in the Fall of 2017. She noticed some moisture on her basement wall, and the carpet on the basement floor felt wet.
I am always happy to answer this kind of call - it feels good to be able to help clients troubleshoot problems and get potential solutions without making them shell out a few thousand bucks to a contractor or basement "waterproofing" company who has a vested interest in finding the most expensive fix.
Plus, I think it helps them to better understand their home and learn to think about these issues in a different, more logical way. This helps ease the panic that often comes when you find an unexpected problem in your home.
In this case, I listened to her concern, and had her text me a few photos. Within minutes we identified the source of her basement moisture problems - the roof.
Maybe this seems counter-intuitive, but over the last 15 years of inspecting homes of all types, if there is one thing I have learned, it is that roof drainage and gutter issues are the biggest cause of wet basements.
Think about it for a second: unless you have a plumbing leak, all that water that is now inside your basement, started out on the outside of the home. That means that we need to look there for the source of the water.
About 99 percent of the time, if you see a wet area in the basement and go outside to the corresponding location and look up, you will find the problem. Roof drainage problems tend to direct water to the ground around the home. When the ground is totally saturated, the water will be wicked towards the drier basement interior. Often this is a fairly limited amount of moisture resulting in damp odors, white mineral deposits (called efflorescence), and maybe even darker staining, which is usually mildew or mold growth.
Small gaps between stones, small cracks in a concrete wall, or cracking of mortar joints between masonry blocks can allow more significant amounts of water to enter. This usually results in visible moisture and mold growth.
In a worst case scenario, excessive ground water can be forced up around the perimeter or through cracking in the slab floor of the basement, causing ponding or water accumulation.
In most of these cases, the underlying cause is usually something simple:
Gutters filled with leaves cause damming and overflow, dumping water on the ground around your foundation.
Kids playing with a ball get it stuck on the roof, where it rolls to your roof drain or scupper box, blocking it and causing rain water to run down your walls instead of into the downspout and drainpipe.
Sagging gutters, missing caulk, loose downspouts, blocked ground drains, and downspouts that don't extend away from the home are all common reasons for basement moisture problems.
The good news is that in most cases, the solution is easy and inexpensive.
Identify where the moisture seems greatest, then go outside and look up. Chances are good that this will identify the source of the problem. Watching how water flows outside during and after a rainfall will help you identify the critical areas to maintain and can show you where your home is most susceptible to water penetration.
Then, it is usually as easy as getting on a ladder and removing obstructions, applying sealant (yes, Flex Seal really does work), or correcting the slope of the gutters.
You can also do some preventative maintenance to try to keep the problem from happening in the first place.
Keep ground drains clear of leaves and debris - the more water that flows into them, the less there is around your foundation
Extend downspout terminations at least 4-6 feet from the base of the home
Clean gutters and downspouts regularly - if you have lots of trees around, this may be as often as every few weeks in the fall
Grading should slope away from the house with a pitch of at least 1 inch per foot for the first 10 feet
Use of urethane caulk, or an asphalt backer rod can seal the gap between a patio and wall where water can enter
All horizontal surfaces (patios, porches, etc) should slope away from the home to let water run off away from the foundation
Repair and seal gutters especially at seams and elbows to prevent leaking
One last note - most basement waterproofing companies WILL NOT correct the source of your basement moisture. They will manage it once it is inside with some combination of french drains, sump pumps, plastic sheeting, and dehumidifiers. While each of these has some merit, NONE of them fix the problem - they all treat the symptoms.
It may seem counter-intuitive, but the key to a dry basement starts with your roof and grading. Of course, all Precision Home Inspection clients have some extra protection to deal with these issues - in this case, our 5 Year Roof Leak Protection Plan, and our MoldSafe Warranty could help cover the cost of the unexpected. Now get out there and clean those gutters!
Philadelphia's Premiere Home Inspector