Just looking for thoughts about sealing an attic that has HVAC equipment in it by using a netting product and dense packing cellulose in the rafters. I have seen this before, although I usually see it combined with foam on the roof deck.  Home is in southeastern Virginia, climate zone 4 and we traditionally do not insulate between the rafters, just the ceiling. The home in question has 85 can lights and we are looking at a cost effective way to eliminate the air flow through these bad boys.



Views: 1393

Reply to This

Replies to This Discussion

Hi Craig,

Although I would love to have a simple fix for this seemingly simple problem, I would be concerned about UL and electrical codes.  I read over the page you provided and saw reference to energy codes, but no reference to electrical codes.  As for UL, if the can was rated, which they usually are, it would probably no longer be rated with this addition.  Building boxes and all of the fixes I have seen so far do not solve our problem.  Replacing the can does.

My opinion and 98 cents will buy a $1 cup of coffee, but we need code compliant solutions.


I contacted the manufacturer and found that they are UL listed. It was not on the website....it's sister product does have the listing in the description. It is the non-removable version that uses pressure clips http://www.affordablequalitylighting.com/docs/indoor/recessed/6in12...

That said, technically, the trim needs to be tested with the housing, which is why they list other fixtures it has been tested with. So if the fixture your installing into has those model numbers, your good. I know that thousands of these have been installed in the Pac NW, even in programs. I don't see how a trim that allows less heat to pass through the fixture by making it air tight is going to make a fixture more dangerous. Of course in our world lawyers exist, so the paranoid can legitimately avoid this trim.

The questions that come to my mind, is whether there is an issue with the UL listing of fixtures that get covered by a box of drywall. Or when insulation is installed over non-IC rated cans requiring a cover or dam, how many lights can really get 3 inches of clearance when half the lights are installed right next to a stud, or have an arm that runs 8 inches off to the side that holds the wiring box.

I would install these in my own home with no reservations whatsoever, but I can understand one being cautious due to liability concerns.

iT'S ALL ABOUT THE HEAT. LEDs can be used to replace bulbs in recessed lights in ceilings. Then with the low temperatures, the fixtures can be sealed and covered with insulation. With traditional recessed lighting options, this space needed to be free of insulation to protect from intense heat build-up and likely fire hazard.

The savings from this one feature alone amount to a huge improvement over our current path of leaving these penetrations in our ceilings largely open to attics, launching the household air up and away. Any serious retrofit of living spaces calls for LEDs to replace traditional recessed lighting penetrations to eliminate this waste, reducing the passage of conditioned air out through these ejection pathways and restoring integrity to the most critical interior surface of our homes.

In addition to massively reducing the failed integrity of ceilings by plugging the leaks known as recessed lights, saving us electricity expense with cooler and brighter bulbs with all the features we love, and outlasting previous bulbs by years, these LEDs are also better for the environment as they use no mercury like the compact fluorescent lights (CFLs) do. The LED makeover is a simple, resounding win-win for your wallet, your delightful home and the environment.

I agree there is more to this picture than meets the page. The RISE in CFM50 came with the addition of 1400 sq. ft. and a ton of openings to the outside irrespective of what dense packing the rafters did.

85 can lights open to an attic at 50 watts each (4.250 KW) equals seventeen feet of baseboard heaters launching over 14,000 BTU every hour up and away. If this much energy didn't enter the mind of the designer/builder, then I would expect other anomalies too.

I agree that LEDs are the way to go. The issue I run in to is that when retrofitting a home, the expense for insulation in the attic can be costly (depending on the size of the house), and then telling a homeowner they need to spend another $100 or so per recessed light can be a hard sale. Especially if they have a lot of recessed cans in their home. I always try to educate them on the benefit of installing LEDs but sometimes the budget just won't allow for it. In that case, we build the boxes. 

On the occasions that I can persuade them to install LEDs, I like to use the CREE LR6. It's a great replacement light. Check out this link and video.....they are extremely easy to install. 


Joseph and Chad, to my knowledge the only approved method for installing a cfl or other lower temperature lighting device like an led, involves installing an approved permanent modification to the fixture.  I have seen a pin type cfl modification to achieve this.  But, even if I wanted to use or recommend this as a solution, I would be sure it met with local approval.  However, it is permanent, meaning, no one can simply switch back to the old high temperature lamp, not knowing that other modifications may have been made that might create a problem.  My advice is to use properly tested methods approved by the local AHJ and don't put yourself out on a limb with innovations for which YOU become the responsible party. 

I totally agree that we need a solution for this, but at the present time, the best solution is to replace the recessed fixture with one that is IC and air sealed.  I'll paraphrase an old saying "energy auditors will answer all questions, it's just that sometimes the answer has to be NO".


Even with adding 1400 sq. ft., a test-out reading of 4500cfm50 is wrong.  Two possibilities; either the building was made worse or the test-out was done incorrectly.  If the attic space was included without closing off soffit and ridge vents, the result would indeed be more leakage.  

Another possibility is the A-ring was put on without changing the manometer CONFIG setting.  On a Minneapolis blower door the A-ring WITH CONFIG CHANGE would have read at test-out 1686cfm50. Ask the test-out auditor if he/she had to add the A-ring.  If so, then he/she didn't have 4500cfm50.

What is the roofing material? Any moisture migrating through the roofing shingles or through the cellulose needs an out.  If venting was poorly done, then it probably ties into the conditioned space and would increase test-out numbers.

Bringing the HVAC and can lights into the envelope would typically be a good idea, it's a question of paying attention to the details of a relocated envelope.

Brad, the idea of bringing the attic is a good one from a distribution efficiency perspective, as well as the attic leakage issue (with the can lights). Dale, I agree the ring configuration may have been incorrect for test in or test out. Another possibility is that there was not a correct separation installed between the soffit and/or ridge venting and the (now conditioned) attic space. Brad this is usually done with a rigid foam barrier (to create a dam at the exterior edge of the walls near the soffitt) and spray foam over this (to seal the edges and secure the dam in place), and would have to be completed in preparation of the dense packing operation. Another consideration overall (not related to the leakage increase) would be the installed R-Value of the dense packed rafters. Netting works well to hold the material, but you can enhance the R-Value and make the cellulose cavity more air tight by laminating rigid foam over the rafters. This wouls substantially reduce heat flow (into or out of the space) through the rafter. If they are making the attic into living space, the foam sheathing can be covered with drywall and finished or another finished covering (such as T&G pine).


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.

Latest Activity

Richard Beyer replied to Howard Katzman's discussion UV lights on filters
"Howard, There are numerous manufacturer's who swear these systems work and then you have the…"
6 hours ago
Christopher Morin posted a blog post

How do You Test a TXV?

  Thermostatic Expansion Valves (TEV or TXV), one of the most popular metering devices for…See More
10 hours ago
Howard Katzman posted a discussion

UV lights on filters

 recently saw UV bulb installations in 2 HVAC systems in a home. Each system had the Lennox Healthy…See More
12 hours ago
Don Fitchett joined Michael Stuart's group


This group is dedicated to knowledge sharing and discussion of infrared thermography for building…See More
12 hours ago
Don Fitchett commented on Diane Chojnowski's group Pinterest
"While most of our (BIN95.com) energy post and boards are industrial related, there are crossovers…"
12 hours ago
Don Fitchett joined Diane Chojnowski's group


Do you have a Pinterest board for energy topics?Post the link to your Pinterest energy board in the…See More
13 hours ago
Profile IconJosh Guenther, Deborah Green, Kenneth Brooks and 3 more joined Home Energy Pros
13 hours ago
Jim Gunshinan commented on Jim Gunshinan's blog post My Energy Upgrade California—The Numbers Are In
"Hi David, to answer one question, the crawlspace was covered with thick poly and the seams were…"
14 hours ago
David Eakin commented on Jim Gunshinan's blog post My Energy Upgrade California—The Numbers Are In
"Jim, Maybe a little more detail on the project is in order. You say that your crawlspace is now…"
14 hours ago
Jim Gunshinan commented on Jim Gunshinan's blog post My Energy Upgrade California—The Numbers Are In
"Ed, no problem, I caught your meaning. Ted, I made a judgement that a mini split would be the best…"
14 hours ago
tedkidd commented on Jim Gunshinan's blog post My Energy Upgrade California—The Numbers Are In
"That makes sense.   What are your criteria/metrics for determining what might be the…"
14 hours ago
Ed Voytovich commented on Jim Gunshinan's blog post My Energy Upgrade California—The Numbers Are In
"Yikes!  Not only did I misspell "roof" as "rood," I also meant to more…"
14 hours ago

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service