· Michael Blair
Encapsulation costs real money and gets recommended almost universally by companies that sell it. In Middle Tennessee it genuinely is the right answer for many houses, and a partial measure is enough for others.
What you actually get
Lower indoor humidity, which improves comfort and reduces cooling load. Wood moisture content brought down to where fungal growth stops. Musty odour removed at source.
Also a crawl space that can be used for storage and entered without unpleasantness, and ductwork that is no longer running through a hostile environment.
When the full job is justified
Standing water or persistent damp. Wood moisture readings above about 20 percent. Visible fungal growth. Insulation that has fallen. A musty smell upstairs. Ducts in the crawl.
Several of those together make the case straightforwardly.
- Standing water or damp ground: yes
- Fungal growth on joists: yes
- Ducts running through the crawl: strongly favours it
- Dry crawl, good drainage, no odour: a barrier may suffice
- Slab house with no crawl: not applicable
When less will do
A crawl that is genuinely dry, well drained, and free of odour and growth may need only a good vapour barrier over the ground, which is a fraction of the cost.
That is a real option and worth asking about, though it is not what most encapsulation companies lead with.
What to check in a quote
Barrier thickness and whether it runs up the walls and is sealed at seams and penetrations. Whether the rim joist is sealed. Whether a dehumidifier is included and how it drains.
And whether drainage and grading outside are addressed. Sealing a crawl that water still enters is expensive containment rather than a fix.