Air Sealing a Crawlspace
About a year ago we elected to finish the porch above our crawl space on the front of the house. Both the room above and the crawlspace are now part of the conditioned part of the home. This past winter we did not have as much comfort as expected in the room above the crawlspace and I believe the space is not as air sealed as is needed. Our basement itself needs some attention too so I will comment on that below.
1. Two HVAC supply runs through the crawlspace to the room above and small legs brought off to condition the crawlspace directly (not pictured).
2. 6 mil plastic to seal out the floor, no concrete was poured. This is stapled to the studs on the front part of the home and loosely sealed on the foundation side. This needs to be corrected as it is not completely sealed, therefore, it is not really sealed for mold/ radon. There is also apparent growth of “green” on the underside.
3. Wall construction is effectively wood siding mounted to the studs, and in the stud bay there is R-13 fiberglass with vapor barrier facing the inside.
4. There is a crawl access hole in the foundation to the rest of the basement so sealing the crawlspace effectively adds it to the basement. A small screen is placed where this door used to be to allow air passage. This is where the photo is taken from.
Proposed Correction Action
1. Follow the procedure presented here to add foam board to act as air barrier and then place the fiberglass batts back into place https://www.greenbuildingadvisor.com/article/insulating-walls-in-an-old-house-with-no-sheathing
2. Add additional plastic floor and up walls, staple and tape all around so there is continuous air seal
3. Caulk air gaps/ penetrations and add rim joist sealing with 3X 2” foam board across entire basement
Should I remove the siding and work from the outside of the house to access the crawlspace? How far up do I work and what do I do against the wall/floor above?
What do I do where the top of the board will meet the above cavity/ interact with the wall in the room above?
Any other thoughts or concern?
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