Nobody
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I am looking for a good way to insulate the floor of one section of my house (35ft x 25ft) that is above a dirt floor vented crawl space. Most of the vents are right below the bottoms of the floor joists. This section of the house was built in 1967 and has a 4 2x12 girder that runs down the center of the house. The code calls for R30 and I just finished installing a new 6 mil polyethylene sheeting over the dirt floor doubled up in many areas.
I am a bit nervous about this decision because I spent many difficult days crunched under the house replacing/sistering about 30 of the 2x10 floor joists....the originals were rotted on the outside ends (blocking between them on the sill plate) and the rot extended about 6-12 inches inward. The wall sheathing was rotted to; just in the lower part near the floor joist outside ends. Bought the house in this condition didn't know about the rot and cant figure out why they all rotted this way.
Anyway, I dont want all my new joists to run into the problem of growing mold/potentially rotting from moisture being trapped in fiberglass batts installed between the joists. Ive read and seen the horror pictures of this happening (moisture in batts and joist rot) in the Southeastern hot and humid climates with vented crawlspaces. From what I have read, vented crawlspaces seem to work fine in the Western Washington climate.
Would installing the fiberglass R30 batts between the joists and then holding them in place by stapling Tyvek on the bottom of the joists be a good idea? I read an article where this was done and also heard that installing rigid foam (1" or ) board over the bottom of the joists has been done....but the rigid foam board option seems to be a very expensive option and seems like it would really seal in the moisture if the joist bays were developed moisture.
Thanks for ideas.
I am a bit nervous about this decision because I spent many difficult days crunched under the house replacing/sistering about 30 of the 2x10 floor joists....the originals were rotted on the outside ends (blocking between them on the sill plate) and the rot extended about 6-12 inches inward. The wall sheathing was rotted to; just in the lower part near the floor joist outside ends. Bought the house in this condition didn't know about the rot and cant figure out why they all rotted this way.
Anyway, I dont want all my new joists to run into the problem of growing mold/potentially rotting from moisture being trapped in fiberglass batts installed between the joists. Ive read and seen the horror pictures of this happening (moisture in batts and joist rot) in the Southeastern hot and humid climates with vented crawlspaces. From what I have read, vented crawlspaces seem to work fine in the Western Washington climate.
Would installing the fiberglass R30 batts between the joists and then holding them in place by stapling Tyvek on the bottom of the joists be a good idea? I read an article where this was done and also heard that installing rigid foam (1" or ) board over the bottom of the joists has been done....but the rigid foam board option seems to be a very expensive option and seems like it would really seal in the moisture if the joist bays were developed moisture.
Thanks for ideas.