I just wanted to say thank you to Martin and the detailed information on this web page…..and give an up-date on too much moisture in the crawl space.
I started off with a 1000 sq. ft, vented to the outside, crawl space. It averaged 3′ high, there was no insulation on the concrete walls and the vapor barrier on the dirt was 6 mil with plenty of gaps.
I did plug/fill the vent holes leading to the outside with 4″ rigid insulation, installed 4″ rigid in all rim joist around the perimeter as well as fastening 4″ rigid to the concrete walls. All gaps were filled with foam and then laid 15 mil white vapor barrier on the ground, coming up the walls about 6″, taping the vapor barrier to the rigid insulation as well as all seams. Because the crawl space vents to the outside were closed and sealed off, I opened a small area in the floor (from crawl space to living) the size of a heat register.
The heat source for this 1000 sq ft log house is a regency warm hearth wood burning fire place. This unit is ducted to a fan in the crawl space that sends warm/hot air to 4 rooms, via 5″ ducting. I simply disconnected one of the ducts, sending that warm/hot air into the crawl space.
What a difference this winter. The floor was a lot warmer and the humidity was down from high 70’s ( when i finished the encapsulation in the summer) to mid 50’s (late Dec with plenty of snow on the ground outside). At one point, the temperature in the crawl space reached 12 degrees.
It was a hugly big job, i must have hit my head 150 times on floor joists but i think it was worth it.
I wander if the humidity in the crawl space will rise in the spring or summer time when there may be more moisture in the outside air? fingers crossed it won’t.
thank you again