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: 260

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

Welcome to Home Energy Pros

Welcome to Home Energy Pros – the unique digital community by and for those who work in the home energy performance arena.

Home Energy Pros was founded by the developers of Home Energy Saver Pro (supported by the U.S. Department of Energy) and brought to you in partnership with Home Energy magazine.  Home Energy Pros is sponsored by the Better Buildings Residential Network. Please honor our Guidelines

Featured Blogs

Seeking Innovation in Roofing Systems

Posted by Sarah OConnell on May 12, 2017 at 9:47am 0 Comments

Oak Ridge National Lab has partnered with GAF to host a technology challenge on roofing systems.  The challenge is part of the online crowdsourcing site, JUMP, and aims to identify innovation solutions for ensuring energy efficient and durable…

Continue

Top tips for maintaining an evaporative cooler

Posted by Kobus Niemand on May 4, 2017 at 3:30am 0 Comments

Evaporative coolers, also known as swamp coolers have become a top choice for anyone looking for an alternative cooling solution from their home or office. In the past, evap cooler technology was limited for use in large operations that have easy…

Continue

Congratulations to the 2017 Race to Zero Winners!

Posted by Home Energy Magazine on May 9, 2017 at 6:56am 0 Comments

The Ryerson University and University of Toronto team topped the …

Continue

Connecting the Dots: Real Estate and Home Performance

Posted by Home Energy Magazine on May 9, 2017 at 6:50am 5 Comments

A new type of conversation between REALTORS® and their clients is changing the real estate industry before our eyes. As homebuyers browse Zillow listings and spend…

Continue

Latest Activity

Andrew Etue added a discussion to the group Job Board
Thumbnail

Washington State Seeks Weatherization Field Monitor

Washington State Department of Commerce in Olympia, Washington is recruiting for a Weatherization…See More
1 hour ago
Andrew Etue joined Diane Chojnowski's group
Thumbnail

Job Board

This group is for posting jobs related to all aspects of the home performance industry including…See More
2 hours ago
Horace Douglas Hunt, Jr. posted a status
"Still looking to purchase a used RetroTec blower door - complete system. Anyone have something available?"
9 hours ago
Sean Lintow Sr replied to Luis Hernandez's discussion Solar panel leasing
"Sorry but no, not that big of a thing up here Biggest issue I see for most is everyone grid ties…"
yesterday

© 2017   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service