Spot the Design Weakness - For Northern Climates

If we had a dime for each weak building assembly detail we saw, we’d be rich. In our 14 years of diagnosing comfort problems for clients; the exposed floor ranks as one of the most stark discomfort features of a home, new or old.

Walking home from the coffee shop Sunday and came across the feature below. Have a look at the photo and see how many design errors you can pick out:

Exposed floor with duct

1- The 2nd floor cavity is exposed above the front door.

2- The metal duct travels in a floor joist cavity past eh stone veneer covering a steel beam.

3- There are pot lights in the eaves.

Even 2LBS spray foam won’t ward off the discomfort in this small but significant exposed floor. How can it, the poor design will handicap it and soon enough all will be covered with lovely aluminum perforated soffit and who will know better.

So here’s the blow by blow, spray foam doesn’t stick well to oiled metal, there’s not enough room between the bottom of the duct and future soffit and though code does allow R12 they won’t get 2″ on the bottom. The duct will lose flow and warmth as it passes so close to the outdoors only to come back in. It runs close and may even touch 2 uninsulated metal beams. Lastly, let’s keep our finger’s crossed that the open joist cavity above the stone wall is continuously sealed otherwise that whole floor cavity above the entire foyer will feel cold to the touch on both sides (main floor and second).

As for the pot lights in the eaves, they are hard to change when they burn out and often create too much heat enough at times to create and ice dam.

Views: 927

Comment

You need to be a member of Home Energy Pros to add comments!

Join Home Energy Pros

Comment by tedkidd on October 25, 2013 at 11:24am

Nice post Greg! 

Mind if I add to your list?  

4 - furnace will be oversized, so cycle times will be short thereby insuring that in heating season this duct will deliver cold air to a cold room. (You don't deliver hot air through cold duct.)

There is only so much you can do when multiple design flaws occur.  Often correcting for a few means the penalty due to the unsolvable (overhang) becomes insignificant.  I'd move the supply in as far as possible and use closed cell spray foam to this whole area.  

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 Mike Kandel's discussion Our Homes Suck – And That's Why Our Kids Have Sinus Problems
""I have no interest in bantering or arguing with you." AGREED! I look at these…"
22 minutes ago
tedkidd replied to Mike Kandel's discussion Our Homes Suck – And That's Why Our Kids Have Sinus Problems
"Todd, it appears Richard is more about getting the last word than about learning a new thing.…"
25 minutes ago
Todd Collins replied to Mike Kandel's discussion Our Homes Suck – And That's Why Our Kids Have Sinus Problems
"Richard,  I don't believe I am missing any points.  As I mentioned... I have no…"
35 minutes ago
Richard Beyer replied to Mike Kandel's discussion Our Homes Suck – And That's Why Our Kids Have Sinus Problems
"Todd, Your missing the point. I can only suggest for you to read all the links attached within that…"
1 hour ago
Tom Conlon replied to Tom Conlon's discussion Whole House Fans - Love 'Em or Not?
"Excellent snapshot, Griffin. You didn't happen to notice the fan manufacturer's name on…"
2 hours ago
Brandon Walton replied to Brandon Walton's discussion 12 Things Every Home Performance Contractor Should Have on Their Work Truck
"Thanks Don! "
3 hours ago
Griffin Hagle replied to Tom Conlon's discussion Whole House Fans - Love 'Em or Not?
"I was aware of but unfamiliar with them until moving to Southern California in 2012. After seeing…"
7 hours ago
tedkidd commented on Scott Mellberg's blog post Lessons from Energy Efficiency Advisors: Getting Homeowners Onboard with Home Performance
"David,  I don't think forcing people to do things works out well for anyone.  Any…"
8 hours ago
David Eakin commented on Scott Mellberg's blog post Lessons from Energy Efficiency Advisors: Getting Homeowners Onboard with Home Performance
""I believe it is our job to educate the consumer, understand the problems, help them…"
8 hours ago
Profile IconGary Fitzgerald, LOUIS ANDERSON and Jeremy Hargreaves joined Home Energy Pros
8 hours ago
eric anderson replied to Tom Conlon's discussion Whole House Fans - Love 'Em or Not?
"In Connecticut’s climate, I am not in favor of them . Either they are the big old style that…"
9 hours ago
Don Fitchett replied to Brandon Walton's discussion 12 Things Every Home Performance Contractor Should Have on Their Work Truck
"Every little bit helps. :)"
9 hours ago

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service