Hey all,

We recently hired a new tech that has previously done a bunch of Home Performance work on the East coast and he has turned me on to a new idea on how to insulate a basement rim joist that is enclosed with a ceiling. I wanted to see what everyone thinks about dense pack cellulose in an enclosed rim joist.

It makes sense that when you have a joist running parallel to the foundation wall that you can drill a hole in the ceiling and fill the joist cavity that is up against the rim. But for the side of the basement that has a wall perpendicular to the joists, can this work?

I have not heard about any contractors here in Portland OR using this technique, but in my mind it seems possible. I just wanted to make sure before we do the install, that it will pass program QC. Before I present it to the program, I wanted to hear some opinions from people that have experience  using this method.

So here's how I see it. If you drill the hole about 2 -3 feet away from the rim joist (towards the inside of the basement) in the basement ceiling, and blow material into the cavity, you should be able to make sure that the rim is fully insulated. I can imagine that the material would taper towards the hole, but as long as you pack it in, it would be fine.

Thanks!

Views: 2211

Reply to This

Replies to This Discussion

Other approved materials are allowed only in section 4 of R302.11 (above), for around mechanical penetrations, not for draftstopping or firestopping in concealed frame cavities.

I was referring to the concealed cavities where codes have required nominal 2" lumber, and where dense-pack cellulose can meet or exceed the same standard.

 

R302.11.1 Fireblocking materials.

Except as provided in Section R302.11, Item 4, fireblocking shall consist of the following materials.

    1. Two-inch (51 mm) nominal lumber.

    2. Two thicknesses of 1-inch (25.4 mm) nominal lumber with broken lap joints.

    3. One thickness of 23/32-inch (18.3 mm) wood structural panels with joints backed by 23/32-inch (18.3 mm) wood structural panels.

    4. One thickness of 3/4-inch (19.1 mm) particleboard with joints backed by 3/4-inch (19.1 mm) particleboard.

    5. One-half-inch (12.7 mm) gypsum board.

    6. One-quarter-inch (6.4 mm) cement-based millboard.

    7. Batts or blankets of mineral wool or glass fiber or other approved materials installed in such a manner as to be securely retained in place.

    8. Cellulose insulation installed as tested for the specific application.

It would be great if someone did a video and u-tubed it.

 

Practically speaking, we seal all holes less than about 2' with foam.  1/2" OSB does the rest.  We foam gypsum common wall gaps at framing, gaps between double walls, and most items.  Average house will have 3-4 places where a piece of wood is used.  

Then you're not complying with code.

In what way are we not complying with the code?
In what way are we not complying with the code?
In what way are we not complying with the code?

See R302.11.1 above.

can you be specific - I am not seeing it

"we seal all holes less than about 2' with foam.  1/2" OSB does the rest"

How is that consistent with the very specific list of allowed fireblocking materials?

And, did you mean holes less than 2 feet? Even if you meant 2 inches, that still exceeds what you reported as the maximum span for foam: not span more than 1-5/16"

Something is screwy with the site tonight

We use OSB to cover the edges of things like soffits then seal with foam, and use extruded styrofoam to seal the tops for energy,  We use the foam to cover the backs of kneewalls, and use it to fabricate top and bottom plates as necessary,  No one says anything at 2" even though the es says 1-5/16 - as they realize what the material is.  We will do this as we seal over 2500 new houses in 2012 in, as I said, 500 jurisdictions (New Jersey has a jurisdiction every couple of miles)

We have excellent working relationships with most of the inspectors that we deal with.  Based on this experience, I have no qualms about using this same system in existing houses, even though the code does not apply for the level of work we are usually doing in retrofits.

Wow thanks for all the advice! I think this is enough info to prove that this is a valid strategy.

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,) and brought to you in partnership with Home Energy magazine.  Home Energy Pros is sponsored by the Better Buildings Residential Network.

Latest Activity

Profile IconAnand Natarajan and Bill Collinge joined Home Energy Pros
14 minutes ago
Scott Stubbs added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase
Thumbnail

Retrotec Commercial & Residential Blower Doors $4800

My business no longer has the need for my Retrotec blower door equipment so I am selling both the…See More
1 hour ago
Chris Stratton replied to Linda Wigington's discussion Weigh in - Honorable Mention? 2nd Base? Half-Way There? 50% Better? On the Path? in the group 1000 Home Challenge
"I like that idea. Giving people as many options to engage as possible (without overwhelming them)…"
4 hours ago
Colin Genge posted an event

Duct Testing 101 Webinar at Online

July 2, 2015 from 1pm to 2pm
•Testing for Energy Code or envelope performance •Measure a known hole to prove to yourself you and…See More
4 hours ago
John Proctor commented on Mariusz Chorazy's blog post Think Your AC Won’t Make it Through the Summer San Antonio TX? We’ve Got the Fixes
"Correction -- according to the most definitive study I know of the median life is 20.5 years. 63%…"
7 hours ago
Linda Wigington replied to Linda Wigington's discussion Weigh in - Honorable Mention? 2nd Base? Half-Way There? 50% Better? On the Path? in the group 1000 Home Challenge
"Chris Another faster option in the interim could be to post a You-Tube video on how to use the…"
21 hours ago
Linda Wigington replied to Linda Wigington's discussion Weigh in - Honorable Mention? 2nd Base? Half-Way There? 50% Better? On the Path? in the group 1000 Home Challenge
"Ted -  That is why the 1000 Home Challenge has two options for determining a project's…"
22 hours ago
Empower Efficiency added 2 discussions to the group Job Board
22 hours ago

© 2015   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service