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: 1328

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.  

Videos

  • Add Videos
  • View All

Latest Activity

CharlieK posted a discussion

Eco-Cottage Program Applauded By Housing Groups, Suppliers & Lenders

AmeriSus a leading player in the eco-kit home business kicked off a new program on MLK-day which…See More
15 minutes ago
Diane Chojnowski posted a discussion

Call for Nominations: Tony Woods Award and Building Performance Hall of Fame

The Building Performance Institute, Inc. (BPI) is seeking nominations for the 2017 Tony Woods Award…See More
1 hour ago
Diane Chojnowski added a discussion to the group 1000 Home Challenge
Thumbnail

January Webinar: Intro to the 1000 Home Challenge

The January Intro to the 1000 Home Challenge webinar will be  Friday, Jan 20 at 10-11:30 AM eastern…See More
1 hour ago
Diane Chojnowski's event was featured
Thumbnail

Introduction to the 1000 Home Challenge Webinar at Eastern Time

January 20, 2017 from 10am to 11:30am
The January Intro to the 1000 Home Challenge webinar will be  Friday, Jan 20 at 10-11:30 AM eastern…See More
1 hour ago
Diane Chojnowski posted an event
Thumbnail

Introduction to the 1000 Home Challenge Webinar at Eastern Time

January 20, 2017 from 10am to 11:30am
The January Intro to the 1000 Home Challenge webinar will be  Friday, Jan 20 at 10-11:30 AM eastern…See More
1 hour ago
Barbara Smith's video was featured

NY State Weatherization Story

The Weatherization Assistance Program (WAP) is an energy efficiency and conservation program administered by the New York State Homes and Community Renewal (...
1 hour ago
Quinn Korzeniecki added a discussion to the group Building Performance Institute (BPI)
Thumbnail

Call for Nominations: Tony Woods Award and Building Performance Hall of Fame

The Building Performance Institute, Inc. (BPI) is seeking nominations for the 2017 Tony Woods Award…See More
2 hours ago
Horace Douglas Hunt, Jr. posted a status
"In the end, isn't it about our #legacy? i haven't left mine yet, have you? #morningthoughts #real"
5 hours ago

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

© 2017   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service