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AU_Prospector 04-14-2010 12:56 PM

Correct insulation install in crawl space floor joists

My home has a crawl space beneath with hardwood floors throughout.

In the crawl there is R-19 Kraft faced fiberglass batts stuffed in between the floor joists with wire supports. The facing is toward the living space, that is when Im in the crawl space and look up, I see pink fiberglass in between the joists. In some areas the pink fiberglass is stringing out in a cobweb fashion. My home inspector told me it is from the weight of moisture.

1) In many spots the wire supports have compressed the insulation. I have a mind to loosen them. Will the insulation decompress naturally?

2) Is this the correct install? The crawl floor is lined with plastic and there are some moisture under this plastic. Also it is always humid in the crawl and my HVAC evap blower sweat in the summer down there. I would almost think the insulation vapor barrier should be installed kraft away from the living space here. This is how my fathers home is. Why have kraft faced insulation here at all, why not unfaced?

travelover 04-14-2010 03:16 PM

When the warm, moist air from your home tries to escape, it is stopped at the vapor barrier. If the barrier is on the heated side, it stops here as a vapor. If it continues through the insulation to the vapor barrier (installed backward) it condenses to water and soaks the insulation.

Bubba Ray 01-04-2011 02:01 AM

What is your location?

handyguys 01-04-2011 08:49 AM

To answer your questions....

1) the insulation may decompress some, it may also fall out or the wire support could fall out. I would leve it alone if not significantly compressed.

2) Yes, the paper face always goes towards the conditioned space.

Sounds like you don't really need to do anything except maybe increase ventilation of your crawl space. Whats the issue?

GBR 01-04-2011 09:38 PM

Post is 8 months old...... I hope he wrapped his ductwork, added an exhaust fan, took care of his water/humidity problem and added house wrap or foam board and a cover under the garbage R-19 low density f.g. (stuffed) batts which give him convective loops;
“How To” Buy/choose Fiberglass Insulation. - DIY Chatroom - DIY Home Improvement Forum

BSI-009: New Light In Crawlspaces — Building Science Information


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