Cold floors, musty smells and half the house's air quality problems start in the crawlspace. Sealing it fixes all three at once.
Vented crawlspaces were meant to dry themselves out; in practice they pull in humid summer air that condenses on cool surfaces, feeding must, mold and floor movement - while winter air chills every floor above. Building science moved on: seal the ground, insulate the walls, control the moisture. Floors warm up, the musty smell leaves, and the air upstairs - much of which rises from down there - cleans up.
We inspect with photos you'll see, fix any water issues first, and quote the encapsulation honestly - including when a simpler fix is enough.
Not always - sometimes rim sealing and a proper vapor barrier does it. The inspection tells us; we quote the minimum that solves your actual problem.
Frequently - a large share of first-floor air originates in the crawlspace. Cleaning up the source cleans up what you breathe.
Water first, always - drainage or sump before sealing. We'll flag it honestly rather than seal over a problem.