Does our finished basement require waterproof materials?

Answered by Jeffrey Anderson ~ November 9, 2012 ~ No Comments

We're considering a basement remodel and got a quote to do floor to ceiling in all waterproof materials. We've only had water in our basement once in 10 years and humidity was at 52 when tested today. We're pretty sure we will invest in their high-powered dehumidifier, but we're not sold on the expensive materials. What would you do?

Mandy - Shenandoah, IA

Jeffrey Anderson

Mandy, unfortunately I can't tell you whether waterproof materials should be used in your basement -- that's a decision that you'll have to make. However, I can say that in over 25 years of building and remodeling homes, I have never once used waterproof materials throughout an entire basement.

In my opinion, if a basement is waterproofed properly at the exterior, the interior should be fine being finished with regular construction materials. By properly, I mean that the foundation should have some sort of waterproofing system in place everywhere it extends below grade, there should be drain tile around the foundation walls to permit good drainage, and the exterior grade should slope away from your home. If need be, a sump pit and pump should also be in place to prevent water intrusion from below the slab.

When the foundation is waterproofed correctly, the only materials used for finishing the interior that need to be out-of-the-ordinary are the framing members that come into contact with concrete. This lumber should all be pressure treated for resistance to damage from moisture.

There might be a few exceptions depending on your plans for the finished basement. If you are going to have a bathroom with a tub or shower, the walls of the enclosure should have a water-resistant material that can stand up to the moisture that may be present when the fixture is being used. Also, if you plan to use engineered hardwood or laminate on the concrete slab, many manufacturers recommend a moisture barrier be put in place prior to the flooring installation.

The dehumidifier may be a good idea, but the current humidity level of your basement is actually within the range the EPA considers to be ideal. Their website suggests that homes with a level between 30 and 60 percent are usually not susceptible to mold and mildew problems.

While the decision must be made by you, I can say that if it were my basement and it hadn't leaked in 10 years, my money would not be spent on using waterproof materials throughout.

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