We know, we know. There’s a lot right with this picture, such as the gorgeous view of Lake Tahoe in the background and the awesome powder for skiing. But from a whole-house-as-a-system perspective, what’s wrong with this picture? What is the owner trying to do, and what would be a better solution?

Thanks to our own Larry Zarker, BPI CEO, for sending in this dandy shot. He offers the following Winston Churchill quote to explain what’s going on here: “You can always trust the Americans to get it right, after they have exhausted every other possibility”.

 

Think you know what the problem is, as well as the solution? Send it to us at lmcdowell@bpi.org.

Tags: April, Building, Chump, Newsletter, Performance, Stump

Views: 156

Replies to This Discussion

Congratulations to Craig Bird of Preston Insulation in Tucson, Arizona for winning last month’s “What’s wrong with this picture?”contest. Craig was not only the first person to send in the correct answer. His answer was far and away the most comprehensive, and dare we say, the most elegant in illustrating what in the world of home performance was wrong with the picture, and what should be done about it.

The picture shows a snow-bound house in front of Lake Tahoe, its roof zig zagged with heat strips.  Says Craig:

“The problem is ice dams.  The home most likely had melting of roof snow which then refroze and created ice dams possibly causing water damage or excessive ice buildup at roof edges. This caused the homeowner to install energy intensive heat strips to melt the ice dams and jack their electric bill through the roof during snow events.  

 

This is caused by:

1)     Air leakage from penetrations near exterior wall

2)     Heat sources close to exterior wall such as heating ducts or recessed lighting cans

3)     Insulation in contact with roof sheathing causing thermal bridging to roof deck

4)     Lack of soffit ventilation

 

The solution:

1)     Air seal exterior top plate with spray foam. It is also important to air seal any other penetration which is delivering heat to the underside of the roof deck.

2)     If recessed lighting is installed near exterior walls, the cans should be ICAT rated to prevent air flow through the fixture. An inexpensive air tight trim kit may also be purchased to avoid changing out fixture itself. Heating duct boots can be sprayed with 2 part foam to prevent heating of roof deck.

3)     Install soffit ventilation at code recommended level at EVERY BAY that is affected.

4)     Install insulation baffles at all soffit edges in order to provide a path for ventilation and carry away any remaining heat transferred from house and cool roof deck. This also prevents insulation from contacting the roof deck (causing thermal bridging).

 

Since it is often difficult to get full insulation amounts at the soffit edge due to clearance, an optimal solution would involve installing ventilation baffles and using spray foam insulation against the baffle and as far in until a full amount of blown insulation may be used. This solution also seals any air exfiltration through the wall top plate at the same time. 

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.

Latest Activity

David Eakin replied to Jamie Kaye's discussion Flickering LED lights
"I also thought that, but I tried to put a CFL in the A-19 outside fixture at my…"
19 minutes ago
Ben Jacobs commented on Scott Mellberg's blog post Lessons from Energy Efficiency Advisors: Getting Homeowners Onboard with Home Performance
" I believe a major problem of government, of energy utilities, and home energy efficiency…"
1 hour ago
Jill Lindman posted an event

EEBA Houses That Work Education & Training at Johnson County Administration Building

August 22, 2014 from 8:30am to 4:30pm
About the SessionsIntro to Houses That Work: In this session participants learn how the many…See More
1 hour ago
Glen Gallo replied to Tom Conlon's discussion Whole House Fans - Love 'Em or Not?
"Title 24 requires whole house fans in zones 8-14 in the prescriptive path only. With many…"
2 hours ago
Jenn Saunders replied to Jenn Saunders's discussion iEnergyApp: Quickly generate professional reports for homeowners and get more contracts!
"Hey Tom, You are most welcome.  iEnergyApp is not free, but it is reasonable and pays for…"
3 hours ago
Jenn Saunders posted a photo

Automatically Generate Clean Simple Reports for Homeowners

Stop spending hours cropping and resizing images, formatting and reformatting a Word document to…
3 hours ago
Eric Sperline added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase
Thumbnail

Beware ebay seller "supermomofps"

I bought a blower door system on Ebay from "supermomofps"  The item was never sent and…See More
3 hours ago
Larry Nissman replied to John Shillito's discussion Fixing a water heater?
"I have to agree with Kurt. 2000 ppm is exceedingly high. I have tested hundreds of hot water heater…"
3 hours ago
Tom White's video was featured

Passive House Revolution - Film Trailer

Looking for energy-efficiency in buildings? There's no need to wait for new technology - Passive House buildings use 80-90% less heating and cooling energy.
4 hours ago
Diane Chojnowski joined Hal Skinner's group
Thumbnail

Radiant Control Coatings

A group where people who work with radiant barrier coatings can let others know all of their uses.See More
4 hours ago
Richard Beyer replied to Shawna Henderson's discussion High Density Foam -- Any Incidents of Cracking in Frame Walls as Studs Dry/Twist?
"Shawna foam pulling away from the studs due to over application will cause spontaneous…"
4 hours ago
Hal Skinner posted a group
Thumbnail

Radiant Control Coatings and their many uses.

A group where people who work with radiant barrier coatings can let others know all of their uses.See More
4 hours ago

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service