As fiberglass absorbs excess moisture in the crawl space it begins to pull apart from itself (delaminate) causing it to look like it's dripping. The moisture also makes it much heavier and with the help of gravity, it falls away from the floor joists.
Moisture in the Crawl Space
Moisture enters through open crawl space vents and is carried in by hot, humid air, rises from the earth, seeps through foundation walls, and penetrations in foundation walls. This crawl space also has some issues with bulk water. We can see that along the foundation walls there is a lot of silt and sediment build up as well as some ware from where the water has moved through the space. Other signs we look for of bulk water are puddling, water lines or staining on walls and piers, and trenches worn by water flowing through the space.
6-mil Vapor Barrier
When installed, a 6-mil vapor barrier is laid on the ground up to piers and walls but is not sealed at its seams or attached to the walls. In fact, because it's so thin, if it were attached to the walls, it would just tear off as soon as a service person crawled on it. These liners are often held in place using "U" shaped stakes which just add more holes to the system. Because the liner is unsealed, it allows moisture from the earth to rise into the crawl space adding to the relative humidity.
Crawl Space Air Sealing
All vents, the sill plate, and any penetrations to outside have been sealed to stop as much air carrying moisture from entering the crawl space as possible. Closed-cell spray foam will then be applied to the foundation walls and then a dehumidifier installed to control the relative humidity.
20-mil Vapor Barrier
A 20-mil CleanSpace vapor barrier is installed on the crawl space floor. All seams are overlapped and sealed. The liner is wrapped and sealed around all piers and mechanically attached to the foundation walls about 6 inches above outside grade to direct any water that seeps through the foundation walls below the liner.
SuperSump Plus & Drainage System
A SuperSump Plus and interior foundation drainage system are installed to collect and pump out bulk water. The pump will carry it away from the home's foundation to a spot on the property designated by the homeowner.