To seal or not to seal the crawl space?

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Author Message   NRL Citizen Username: Nrl Post Number: 223 Registered: 8-2003 Posted on Friday, October 3, 2003 - 10:09 pm:        Looking for some advice. House built on or around 1938. Like many house in MW we have the room that was built off the side of the house over a crawl space. The crawl space is not accessible from the basement but their is a 3 or 4 inch gap between the sill above the cinder block and the joist, allowing air to come in from the crawl space. I have 3 brick size screen vents on the outskirts of the crawl space which let air pass through. Drafts come into the basement and It seems it makes my de-humidifier run longer in the summer and cold air come in in the winter. I want to stop the air from coming into the basement from outside the house so freely. 1) Should I seal of the space between the joist and the sill with strips of wood or use that expanding foam to stop the air flow? OR 2) Should I close the vents up? If I close the vents up the cold air will still come from the dirt floor of the crawl space. Wont it? 3) If the foam is the answer, is that stuff safe for going around steam heat pipes which run up the exterior wall of the home and into the crawl space? Thanks in advance   tjohn Citizen Username: Tjohn Post Number: 1803 Registered: 12-2001 Posted on Friday, October 3, 2003 - 10:39 pm:        The foam will be safe around the steam pipes. The most important consideration in determining the best solution is moisture. You don't want the crawl space to be too damp because it will get moldy. I would guess the following would work. 1. Seal the spaces between the joists and sill with expanding foam. 2. Insulate underneath the floor of the side room. Various do-it-yourself websites describe this type of project. 3. Make sure the crawl space is well-ventilated.   NRL Citizen Username: Nrl Post Number: 228 Registered: 8-2003 Posted on Saturday, October 4, 2003 - 12:56 pm:        Tjohn, I think the "Great stuff" foam is 240 degrees heat resistant. How hot do steam pipes get?   tjohn Citizen Username: Tjohn Post Number: 1805 Registered: 12-2001 Posted on Saturday, October 4, 2003 - 1:35 pm:        About 220 max and probably a bit less.