I am in the process of purchasing a home in Leamington, Ontario. I had it inspected by a home inspector. In his report he stated that it was damp in the crawl space. He said it could be partly due to the fact that at the time we had rain for three days in a row. He said there was no vapor barrier on the ground, but there was plastic attached to the bottom of the floor joist along with insulation. He said I should try and get ventilation into the crawl space. There are only two openings into the crawl space. I have listened to your radio show and know that you always tell people to remove both the vapor barrier and the insulation from the floor joist. Should I try and dry out the crawl space before putting down vapor on the ground and if so how would I do it? Could I make a pair of frames with vents in them to replace the covers of the opening to the crawl space ( the present covers and windows (26x16) that are held in place by screws. Would this provide enough ventilation. If this would be okay how big of a vent should I try and use. I was thinking about regular foundation vents with adjustable louvers in them. Would I want to remove the vents and seal the openings for the winter. There is no insulation on the foundation walls. Should the walls be insulated? If it should be insulated wouldn't I want to make a kind of frame so there would be something at attach the vapor barrier and strapping to hold the insulation in place. Could I use the insulation that is already in the crawl space as long as it is not damp or would I be better to use rigid insulation and glue it to the walls and then put up vapor barrier. If the rigid insulation would be better what type of glue should I use and is there one that you can use in a confined space safely. Any help you can give me would be greatly appreciated.
Answer:
I don't think I'd try to dry it out on the bottom but you won't be able to dry out the upper portion (bottom of floor) unless both vapour barrier and insulation are removed from there. I remove it all and then apply an impermeable sheet to the floor to begin with and then put a fan in one of the vent windows to get rid of the mould and mildew via the other vent. You should have enough ventilation the way things are but the fans will certainly speed things up. For winter months, I think it would be a good idea to reduce ventilation to not more than 12 square inches but open up the rest of in the spring again. Following is a message I send out with all my inspections that concern crawl space venting: Crawl space is a major source of mildew but that can be corrected. First, all insulation has to be removed from the crawl space ceiling - house floor. The whole dirt floor, with all its irregularities, has then to be covered with an impermeable material (6mm polyethylene, an old swimming pool liner, etc.). This has to be firmly and permanently sealed to the existing, well applied perimeter wall vapour barrier - which should be covering insulation rated at least R-20. It also has to be taped to all perforating structural components (plumbing, support posts, etc.). That looks after the crawl space for most of the year. The vents on the walls have then to be adjusted so they can be opened and closed from the outside. This will negate the need for anyone to crawl around down there for seasonal adjustment of ventilation.
