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Re: Insulation on wet basement block

From: scott.halladay@excellus.com
Category: Foundations and Basements
Remote Name: 67.51.180.60
Date: 22 Jun 2005
Time: 08:19 AM

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Question: I have a 9 year old house with a full basement located in western New York. Fiberglass insulation covers the concrete block walls down to about 18" above the floor. I've had to remove the wood strips that were securing the bottom of the insulation to the wall as they were wet and coated with black mold. The walls are wet on the front side of the house and along the wall between the house and the connected garage. The grading on the front is flat and there is only about 4" from the ground up to the base of the vinyl siding. Below are my questions: *Do you have any suggestions for the grading? *Should I remove all of the insulation as it's covering wet block and then coat the walls with Drylok? And is it necessary to replace the insulation?

Answer: Builders Websource recommends that your remove all wet fiberglass insulation and dispose of it properly. Scrub the walls with bleach and a bristle brush to remove any mold and mildew that may be present. Be sure to have ample ventilation prior to applying any bleach or cleaners. Using a product such as Drylok masonry waterproofing paint can help to prevent water penetration. If this works after periods of heavy rain, you can feel safe installing new insulation where the old insulation was removed.

However, you probably have a larger drainage issue that needs attention. If your lot isn't sloped at least 2% away from the foundation, rain runoff will tend to collect at the foundation, seeping into your porous walls. It sounds like the exterior walls were not properly waterproofed below grade and you may not have a drainage system present to intercept ground water. As a result, the hydrostatic pressure is forcing moisture through the path of least resistance which, in your case, includes your basement cinder block walls. It's always best to stop the water at the source, rather than trying to keep it out from the inside. You may need to consult with a basement waterproofing specialist or civil engineering company that specializes in residential drainage issues. If left unchecked, water and moisture permeation can cause unhealthful environments as well as structural erosion of your home.

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