Retention levels are set by the AWPA and inspected by the AWPB and should be stamped with a seal.

.25 lbs per cubic foot – Rated for outdoor use above grade only.

.40 lbs per cubic foot – Rated for ground contact. This will work well for joists.

.60 lbs per cubic foot – Used for wood foundation systems- this is required if you plan on burying your support posts in the ground.

.80 lbs per cubic foot – Marine Use: Freshwater Contact

2.50 lbs per cubic foot – Marine Use: Saltwater Contact