Crawl space encapsulation
Hey Folks – I know the topics has been covered but I am still scratching my head and need some clarification and I will but this project to rest.
I live north of Seattle, WA. in Bellingham – I believe it to be Zone 4a (Marine Zone)
I have about 1000 sq. ft. of crawlspace I am beginning to encapsulate.
I have no bulk water issues.
I have 12 mil SilverBack liner for the walls and 20mil SilverBack liner for the earth.
I found a great deal on new Polyiso fiberglass faced rigid foam board 2″ thick. (Firestone ISO 95)
I have an AprilAire 1830 Dehumidifier to install when complete.
Thus far I have installed and air sealed the wall and rim joist cavities with 4″ Polyiso.
I have also begun to install the same Polyiso board “above grade” to the foundation walls interior.
I understand the optimum detail would be to install XPS/EPS to the exterior.
I could install the XPS/EPS on the interior.
Can I install the Firestone product I have on hand below grade? The perm rating of my product I believe to be 1 perm.
I don’t want to create a mold problem that I do not presently have.
Could I install the Firestone product I have on hand below grade and not install the 12mil liner I have to the walls to to promote a drying to the inside via the AprilAire Dehum? (yet secure/seal the floor liner to the walls)
Question- am I over thinking all of this- would the above grade insulation be satisfactory/helpful and just leave the below grade exposed (no insulation) and simply line the walls with the 12mil.
The walls above my foundation I have installed 4″ of the Firestone board and air sealed. Should I install a VB. Could I run my white 12 mil liner up the framing shy of the floor joist above. I understand a termite inspection area should be maintained at the sole plate on top the foundation.
Question- Having installed 4″ of foam board inside the 2×6 framing cavities leaves me shy of coming flush with the framing – (interior) could I install/float a full sheet of insulation board over the framing to aid in the thermal bridging aspects with that void of an inch+.
Please excuse my “over thinking” this stuff and the questions. I have learned a lot off this site and trying to go carefully when it comes to things like mold.
My objectives with this en devour – I am in a heavily wooded/forested/shaded area, the house humidity is high during the peak times. My crawlspace is somewhat tall, and the wood floors above are a tad cold.
Positive note – this week it has been 24 degrees out. With the insulation installed the and vents sealed the crawl is maintaining 50 degrees. The R/H is at 72% floor still has loose plastic and Dehum not yet installed.
You guys are great – Thanks – William
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