Door R-values?
mapnerd
| Posted in Green Building Techniques on
I can’t find a whole lot of information about doors and their respective R-values. If I want to build a super-insulated home with good ventilation, what are some good choices for door materials and how should they be sealed?
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Replies
I share your concern. There is a good post here about garage door R-values, and I am sure the concepts apply to people doors somewhat, too. Sealing is the name of the game. When I built in '80, I made my doors out of 2x6s and fiberglass, just like a wall. Topped them w/ 1/4" teak plywood. All are working just fine, except the one that opens to the black-rubber covered deck; the sun has warped it a bit, so I adjusted the sealing members to fit. I may have some wood planed and build my own for the new house; it is really not that hard. The concept of using two factory doors around 2" of EPS has also crossed my mind, but that may get stinky. Good luck, and let us know if you find a solid answer. john
Insulated fiberglass entry doors are the best available. They are durable, non-conductive, stable and insulated better than any window you're likely to install. A quality unit will have good weatherseals and an adjustable sill.
Micahel,
You may be interested in this thread at the Passive House Institute bulletin board:
http://www.passivehouse.us/bulletinBoard/viewtopic.php?f=7&t=136&p=528&hilit=doors#p528
Architect Jesse Thompson wrote,
"Doors, however. That's the BIG weak link still for us. Finding a decently insulated, good looking wood entry door with a smartly thought out sill is miserable. It's the big area where form and function are still miles apart. I'm inclined to go get a good sauna door manufacturer to just make us a 6'-8" version and call it an entry door."
Michael,
I haven't yet had enough time to call door manufacturers and ask for specifications, but what you are interested in is the NFRC U-factor for the entire door assembly. Here's some information:
http://oikos.com/esb/37/nfrc.html
My guess is that many door manufacturers don't know, or don't report, their NFRC U-factors.
The NFRC U-factor will be more meaningful than the R-value of the center of the door.