Waterproofing: The first step to a successful basement finishing project

You have decided to finish your basement and take advantage of that extra space in your home. After carefully considering layout, design, and finishes, you complete your project. As you get ready to sit down on your brand new couch, you see a puddle of water on your nicely finished floor – now everything has to be taken down before mold takes over your basement. This all too often scenario, can be easily prevented by first tackling water intrusion and humidity levels in your basement.

Looking For Potential Issues

As you prepare for your basement remodel, keep an eye out for these signs of moisture: Visually inspect all surfaces throughout the basement – is there any water trickling down your walls, either from existing cracks or through the porous surface of the concrete? Check for standing water on the floor and identify where it is coming from – is it a broken pipe? an appliance in disrepair? is the water coming from the ground?.

Next, check for a potential saturated base of your concrete block walls – are the joints lighter in color? Can you see moisture marks?. Look for potential rot or decay on the base of your framing members, excessive rust of metal surfaces, and staining or blistering of wall covering (if any). Finally, is there any damp, humid air? Odor, mold or visible mildew?

What are the main causes of moisture in my basement?

If you do in fact find moisture in your basement, chances are it’s coming from one of the following:

  1. Overly saturated ground from rain and snow. As water looks for the path of least resistance, the porous materials of your foundation become the perfect entry point to alleviate this pressure. Alternatively, any cracks or openings into your basement are an open invitation to allow the water in.
  1. Interior moisture sources such as humidifiers, unvented clothes dryers, bathrooms and stovetops, or broken water lines.
  1. Exterior humid air entering your basement which ends up condensing on cooler surfaces due to improper air circulation.
waterproofing the first step to a successful basement finishing project simply built blog

What are the main waterproofing solutions?

  1. Proper appliance and plumbing vents: if any appliance is causing excess moisture in your basement, it is important to redirect this humidity outside of the space by properly running ductwork and air circulating fans.
  1. Gutters and Downspout: Walk around the outside perimeter of your house and evaluate your gutters, downspouts and surface grading: If your gutters are not properly draining down and away from the house, correct this minor issue and see if it resolves your basement moisture problem. If all rain water is being properly diverted and the problem persists, surface grading may be causing water to flow back into your foundation, which will require proper drainage.
  1. Interior or exterior drainage system: If surface grading is redirecting water back into your basement, have an expert evaluate whether you need a curtain drain, a French drain, or another type of pump-based drainage system.
  1. Sub-slab depressurization system: An active sub-slab depressurization system including a washed-rock layer below the slab is recommended. This draws moist air from beneath the slab and may help to reduce the amount of moisture vapor that enters the home through openings in the slab. It also assists in controlling radon and other soil gases. Sumps and other open connections to the soil outside the foundation and below the slab should be blocked and sealed.


We hope this guide has given you some tools necessary to start your basement finishing project on the right foot. At www.simplybuilt.biz we are ready to help you bring your vision to reality, by providing remodeling expertise and a passion for design!

See you soon!

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David Castaneda
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