Crawl space

Published on March 4th, 2013 | by Henri


Replacing the plastic on dirt floor of crawl space

Q.    We have a summer home in Brigantine, NJ which is a 1950s split level with hot water baseboard heat. The crawl space below the kitchen and living room has a dirt floor which is presently covered with plastic (in very poor shape).  The kraft paper on the insulation on the floor joists is dripping water.

I know the plastic must be replaced but am wondering what is the proper way to do this. While doing this, would it be advisable to glue 2″ foam insulation to the 3 exterior walls and regular insulation to the studded interior wall to help in keeping the area warmer during the winter to prevent the water pipes to the kitchen and bathrooms from freezing? There are also hot water heating pipes that run through this crawl space. Some of the pipes are insulated with foam insulation and some are not.Would it also be advisable to block the two vents in the cinder block foundation during the winter?

Last winter I checked the temperature in the crawl space and it was approximately 45 degrees F when the outside temperature was in the 20s. The heat in the house is left on at 50 degrees F all winter. Any information you could provide would be helpful.

A.    You can leave the existing plastic in place and put another layer of 6-mil plastic over it. Be sure it covers the entire crawl space. Overlap any joints by a couple of feet and, if you experience leakage through the walls, bring the plastic up the walls to a point above the outside grade. Tape it in place with duct tape after brushing the spots clean so the tape will adhere.

Remove the wet insulation and dispose of it in heavy plastic bags; do not replace it. Cover exposed skin with cream, wear a dust mask, a plastic shower cap, tight clothing and eye protection, and thoroughly shower afterward. Adhere 2-inch thick extruded polystyrene to the masonry walls with dabs of Styrobond or polyurethane caulking on clean surfaces. Staple fiberglass to any frame wall facing outside, but there is no need to insulate an interior wall; it is best to let all inside spaces “communicate.” Insulate the non-insulated heat pipes with neoprene foam.

Finally, close the foundation vents year-around. In summer, they introduce a lot of moisture — probably the reason why the fiberglass floor insulation is dripping wet. Once you have added new plastic to the floor, there should no longer be a moisture problem.

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