Treating crawl spaces (with ductwork) when the adjacent basement ceiling is insulated.

I am currently speaking with a homeowner who would like to replace the existing FG batt insulation in the ceiling above his crawl space. The crawl is connected to the basement, and the basement ceiling is insulated with FG batts as well. The crawl has ducts insulated to R-4.2 throughout it. The crawl floor is a thin layer of concrete (about 1").

I spoke to him of two options:

1. Slap R-19 un-faced FG batts in the ceiling, and then slap 1/2" to 1" of foil-faced rigid foam to the underside of the floor joists.

OR

2. (This is my preference). Lay down 6-mil poly across the floor of the crawl, and adhere the poly to the crawl walls (up a couple of feet). Then install 2" of foil-faced rigid foam to the crawl walls. 

I will also be insulating the rim\band joists throughout the basement.

Any advice?

Views: 144

Reply to This

Replies to This Discussion

I agree with your preferred option.  If the connected space is climate controlled then stopping moisture and outside air from entering is the best option.  Only putting the FG batts in the ceiling of the crawl space would still leave the influx of air to deal with and it would decrease the efficiency and comfort of the home.

Thanks Tim. I have been pushing this option, and I think the homeowner is going to bite.

I would suggest a true vapor barrier product or ASTM  E-1745

From my short education on the product you want to make sure that the product is rated for the application. It is critical that the product is mechanically fastened to the wall and sealed. If there are any piers the product should be fastened and sealed to it as well.All seams sealed with tape approved for the product

I use 1x2  and ramset for fastening and duct mastic for sealing.

It is tedious, boring and often unappreciated in a challenging space.

I would always be concerned about the walls ability to dry. If the outside stem wall is buried I would think twice before insulating it

That is some really valuable input Glen. I definitely will continue to think this one through.

Thanks.

Patrick

RSS

Home Energy Pros

Home Energy Pros was founded by the developers of Home Energy Saver Pro (sponsored by the U.S. Department of Energy, under the American Recovery and Reinvestment Act) and brought to you in partnership with Home Energy magazine.

Latest Activity

Mark Richardson added a discussion to the group Renewable Energy
Thumbnail

Disasters & sustainable energy

Read my response to J.C. Martel's discussion:…See More
2 hours ago
Mark Richardson replied to J.C. Martel's discussion Disasters & sustainable energy
"Hi All, Interesting topic - myriad issues in play here, but I’ll try to touch on the ones I…"
2 hours ago
Eric Kjelshus replied to Johnny Ritzo's discussion Selecting a Water Heater
"I have been using  Rheem or State or Brad/white PVC flued tank type hot water heater…"
14 hours ago
Bachi Brunato replied to Bachi Brunato's discussion Boxing and Insulating Around Non-ICAT Cans
"As it turns out, we have 10 Halo 99RT housings with Halo 998P Eyeball trim in the kitchen. The trim…"
17 hours ago
Bachi Brunato's discussion was featured

Boxing and Insulating Around Non-ICAT Cans

I have a client with 16) 4" halogen recessed light fixtures in the attic.I'd like to cover the cans…See More
18 hours ago
Johnny Ritzo's discussion was featured

Selecting a Water Heater

I am looking at updating the heating and water heating systems in a rental home I recently…See More
18 hours ago
George Kopf's discussion was featured

Misting Aeroseal in Pressurized Home = Amazing Air Sealing Innovation

As a training program manager for a non-profit, I am often too busy managing my program to catch…See More
18 hours ago
Tom Delconte's blog post was featured
18 hours ago
Christopher Morin's blog post was featured

Selling with Rebates: The Simple Payback

  The easiest way to show a homeowner how their investment in high-efficient equipment will help…See More
18 hours ago
Edward Foskey's blog post was featured
18 hours ago
Mike Rogers's blog post was featured

HOMES Act introduced with Bi-Partisan Sponsorship

We don't see a lot of bi-partisan bills in Congress these days. Here's one focusing on home…See More
19 hours ago
Mike Rogers posted a blog post

HOMES Act introduced with Bi-Partisan Sponsorship

We don't see a lot of bi-partisan bills in Congress these days. Here's one focusing on home…See More
22 hours ago

© 2013   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service