Doors: blowing agents and thermal bridging of multi-point locks
I've been shopping for doors, and mostly looking at foam-filled fiberglass in order to get a decent R-value. Most are polyurethane (PU) foam, and I'm guessing that they use HFC if not HCFC blowing agents. I'm not thrilled by the global warming impact of those. But it seems very difficult to find any information on what blowing agents they use. Therma-Tru replied to my query and said they "do not disclose the formulation of the blowing agents used." The only line of doors I could confirm uses low-GWP blowing agents is Jeld-Wen, who use Neopor, which is a graphite enhanced EPS foam, so you get similar R-value to PU, with a relatively benign hydrocarbon blowing agent.
Question1: does anyone know of other door manufacturers who are willing to tell you what is in their foam?
Question 2: I also need a garage door. R-value there won't affect energy use as it's not a conditioned space, but it will affect the temperature the garage floats at so I'd prefer some decent R-value there. I found that Clopay gives you the option of PU or EPS, though they don't tell you what the PU is blown with. But there are quite a few with 2" thick EPS, which is thicker than most. Anyone know of another garage door manufacturer who discloses their blowing agent?
Question 3: It seems that multi-point locking systems provide an improved air seal both by preventing the door from warping and being loose at the top and bottom, and by drawing it in to the jamb as it latches. But they are installed by putting a metal strip along the door edge. That seems to me like the opposite of installing a thermal break. My intuition is that it's OK. The fiberglass skin won't collect heat and conduct it to that thermal weak point the way glass or a metal skin would. But does anyone know of any data on the effect on U value of adding a multi-point lock to a door?
Overall, I'm feeling good about Jeld-Wen doors with Neopor insulation and a multipoint lock, and Clopay garage doors with 2" of EPS, but I'm surprised how little information there is on this, so I'm curious to hear whether others have considered these issues.
Posted Thu, 09/04/2014 - 14:42
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