Do You Still Need Crawl Space Insulation After Encapsulation?
One of the questions we hear most often after encapsulation is: 'Do I still need insulation?' The answer is usually yes — just in a different place than you might expect.
Why insulation under the floor stops making sense
In a vented crawl space, fiberglass batts between the joists try to insulate the heated rooms above from the cold crawl space below. The problem is the batts get damp, sag, and grow mold.
Where insulation should go in a sealed crawl space
Once the crawl space is part of the home's conditioned envelope, insulation belongs on the foundation walls, not between the joists. This typically takes the form of rigid foam board or spray foam adhered to the wall liner.
R-value targets for Middle Tennessee
Most homes in our climate do well with somewhere between R-10 and R-15 on the foundation walls. Local codes and individual conditions can shift that, but it's a fair starting point.
What to do with the old fiberglass
Existing fiberglass between the joists is usually removed during encapsulation. It's almost always wet, sagging, or moldy by the time the encapsulation conversation comes up — and leaving it in place tends to undermine the new system.
Conditioning the space
In some sealed crawl spaces, a small HVAC supply register is added to keep the space gently conditioned. In others, the dehumidifier alone provides enough control. A good installer will explain why one approach is being used over the other.
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