After two very cold winters (and some very cold feet) we decided it was time to have the crawl space under our 125+ year old home insulated. We considered trying to do it ourselves, but opted for professionally-applied spray foam insulation instead as it was more appropriate for the circumstances. In addition to applying spray-foam insulation to the insides of the foundation walls, they sealed joists and laid poly over the dirt floor. The quoted price was reasonable, they came out and did the job within days of me calling them, and the process was fast. Absolutely no lingering chemical odour, either! Once the insulation dried, it was completely odourless. Couldn't be happier.