Several types of insulation are effective for crawl spaces, with spray foam and rigid foam boards being two of the best options. Closed-cell spray foam insulation is a strong choice because it effectively repels moisture, resists biological growth, seals the air, and provides excellent thermal protection, especially in hard-to-reach areas. Rigid foam insulation boards are another excellent material as they insulate well, resist water damage, and will not settle over time like fiberglass or cellulose.

You should plan on waiting at least a year and ideally two to three years after construction before finishing your basement. This will give the foundation time to settle in response to the weight of your home and the expansion of the surrounding soil. You can then repair your foundation and seal any cracks as needed before finishing it to reduce your risk of future leaks or other issues.

The primary downside to crawl space encapsulation is the high cost, which can be several thousand dollars. Additionally, the process can make future repairs more complicated by limiting access to plumbing and electrical wiring within the crawl space. Encapsulation also requires sealing off any vents, which can be a disadvantage for home designs that benefit from the airflow they provide. It's recommended to consult with a crawl space contractor to determine if the benefits outweigh these potential drawbacks for your specific home.

Yes, usually you will need some kind of vapor barrier on the exterior walls when the framing is attached to concrete and masonry surfaces.