underfloor insulation question
As a homeowner, it’s getting to that time again when the weather warms up, and so does my to-do list. After reading extensively about underfloor insulation, the do’s and don’ts, I found that the bats were installed improperly. The previous owner of the house had someone install bats with foil barriers facing down. The crawl space is covered in heavy mil plastic, but not sealed against the interior sidewall of the foundation.
I’ve been in the house over a decade, and I’m growing concerned about moisture damage and mold on the floor joists. I live in Seattle, and the house’s foundation is equipped with typical crawl space vents.
I know I need to address this issue, but was wondering what’s the best method to re-insulate (cost is a definite factor). Is it even critical to insulate the floor joists? I’ve read through the recent “mixed” climate building science foundation book, and understand the principals, but also seek advice from experienced forum members.
Thanks in advance,
Jesse
Replies
Check for possible mold issues. Maybe you don't have a problem. You could take off the foil backing. You could slice it to relieve the vapor retarder. You may not have to replace all the insulation if there is no moisture damage. Sounds like the ground moisture barrier is a good start although as you say ... not sealed against the wall. Maybe you could mitigate that a little.
You do intend to vent this summer right?
I'll check in a few places to see if mold has found its way into the cavities. My biggest concern is time. I don't know when this floor was insulated, as it may date back many years prior to me buying the house. The existing bats are stapled to the bottom of each joist, creating a smooth "ceiling" in the crawlspace, but all that trapped air that cools and condenses moisture could have been slowly damaging the joists.
As for venting, there are 4 foundation vents, which I sealed up this winter, but just recently opened up again. I've read that it's advisable to modify a crawlspace into a conditioned air space and vent it through a stack, but that takes a lot of work.
I'd check joist bays near the perimeter or vents ... where the cavity might be the coldest which is where you might have the highest potential for condensation.
There are a couple of schools of thought w/ crawlspaces ... seal them up and 'condition' or vent in summer, close in winter. Not sure if either is necessarily right or wrong. Could have long discussions either way about this topic.
To followup, can I simply flip the foil faced insulation over in the joist bays, saving material and disposal costs?
goalieump
I need a favor.
I've asked this question several times and got no answer.
To whom did you reply to in your thread above about flipping the insulation? It shows you replied to yourself-so there'll be no notice to whomever you're asking the question of.
This has happened several times when an original poster has responded and no one seems to know if it's a forum glitch or if you (and others) have just hit the reply button on the First Post in the thread (Original Post).
If you could reply to my question, we might have an idea what's going on.
thanks.