5-ply hot pressed wood doors

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Author Message George A. Everding, AIA, CSI, CCS, CCCA Senior Member Username: geverding Post Number: 731 Registered: 11-2004 Posted on Wednesday, March 26, 2014 - 04:47 pm:    I am curious if how the specification community curently feels about the cold pressing some manufacturers are using for their 5-ply doors. I am of the school that considers hot pressing the only reasonable way to make an architectural flush wood door. But gluing technology has advanced considerably since my old school days. How do my experienced colleagues feel about cold pressing? Any changes in your opinions recently? George A. Everding AIA CSI CCS CCCA Allegion PLC (formerly Ingersoll Rand) St. Louis, MO Lynn Javoroski FCSI CCS LEEDŽ AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 1785 Registered: 07-2002 Posted on Wednesday, March 26, 2014 - 05:16 pm:    No changes. Until one of my trusted advisers from a trusted wood door manufacturer says otherwise, I'll stay with the tried. Andy (Unregistered Guest) Unregistered guest Posted on Thursday, March 27, 2014 - 07:25 am:    I worked for a distributor who sold both cold and hot pressed wood doors. I saw no difference in quality or durability. The warranties were the same. I believe cold "pressing" process has been used for over twenty years, so it is not a new process. I think the cold press doors we sold may have been 7-ply. I don't remember ever having a sub request be rejected because of the cold press process. Some of the manufacturers of the hot "pressed" doors said hot pressing was better, but I always chalked that up to trashing the competition. We actually stocked the cold pressed doors in our warehouse, so we sold quite a bit of this product. John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 1565 Registered: 03-2002 Posted on Saturday, March 29, 2014 - 06:18 pm:    My recollection was that only allowing hot-pressing was a proxy for 5-ply doors, as all 5-ply makers did that and few or no 7-ply did. That's not true now. In the meantime, glues and processes are better and I would doubt cold-press is any worse than hot. Lot's of amazing millwork and carpentry is done with, essentially, cold-curing glues so why should a door be different? ken hercenberg Senior Member Username: khercenberg Post Number: 739 Registered: 12-2006 Posted on Saturday, March 29, 2014 - 09:36 pm:    I recall some 7-ply manufacturers insisting that their cold-process EVA was better than the hot-press Type 1 adhesives. Then they said that the EVA breaks down with heat so they can't use hot-press, never addressing the possibility of changing adhesives. Apparently the number of plies, which determines how much adhesive is needed to hold the door together, and the thickness of the plies, is a bigger factor than some people want to admit. The way it was explained to me, the thicker the ply, and lower the number of plies, the better the door. Ever try a 3-ply door? J. Peter Jordan Senior Member Username: jpjordan Post Number: 711 Registered: 05-2004 Posted on Sunday, March 30, 2014 - 08:44 am:    Fewer plies mean thicker plies since the thickness of the core remains the same. I recall a presentation by someone from VT Industries about ten years ago in which the presenter reported that the face plies on each side of the core are essentially 3-ply plywood which are then assembled into the door unit. Five ply doors are made up of the individual veneer plies. I wonder if this affects the choice of adhesives. ken hercenberg Senior Member Username: khercenberg Post Number: 740 Registered: 12-2006 Posted on Sunday, March 30, 2014 - 12:49 pm:    From what I recall, cold press using EVA allows manufacturers to stack multiple doors in a press; I presume they have means of equalizing the pressure throughout the stack. I also presume that hot press doors are pressed one at a time, but I don't know that for certain. Sheldon Wolfe Senior Member Username: sheldon_wolfe Post Number: 749 Registered: 01-2003 Posted on Sunday, March 30, 2014 - 01:48 pm:    Neither AWI nor AWS suggests one is better than the other, and they include 9-ply doors. Twenty years ago, I was told that 5-ply doors had a thicker face veneer, but current AWI and AWS standards require a 0.02 inch thick face veneer for transparent finish for both 5- and 7-ply doors. For what it's worth, bearing in mind that the source is a 5-ply manufacturer: http://continuingeducation.construction.com/article.php?L=360&C=1113 And http://www.oshkoshdoor.com/pdf/hot_press.pdf suggests you may want to add more to your specifications. As Andy notes, both constructions are available with the same warranty, so as long as you make sure you address the appearance issues they should be equivalent. Many of our clients require 5-ply doors, but I suspect that is due more to inertia than to performance. For other clients, we have allowed 7-ply doors. I don't know what showed up on site, but we have had no problems that can be attributed to construction of the doors. ken hercenberg Senior Member Username: khercenberg Post Number: 741 Registered: 12-2006 Posted on Sunday, March 30, 2014 - 02:25 pm:    I thought the AWS defers to WDMA for the most part at this point since there had been so many discrepancies between the two. One of the most important items to include is bonded core regardless of whether you're using 5 or 7 ply technology. I find the designators Extra-Heavy Duty, Heavy Duty, and Standard to be a fair way to describe need. I wonder if my clients could live with 5-ply at Extra-Heavy Duty and 5 or 7 ply at Heavy Duty and Standard usage. BTW, I use SCL core for Extra-Heavy Duty and PC-5 at Heavy Duty and Standard so I don't usually need to worry about through-bolting or adding blocking for closers and hardware. Is that pretty much what everyone does? ken hercenberg Senior Member Username: khercenberg Post Number: 742 Registered: 12-2006 Posted on Sunday, March 30, 2014 - 02:52 pm:    Sheldon, I just read the Oshkosh Technical Bulletin you linked. Wow, that is not only very educational but very disconcerting. I would love to hear a rebuttal from the cold press side of the aisle. I think I'm going to continue sticking with hot press only at this point. Sheldon Wolfe Senior Member Username: sheldon_wolfe Post Number: 750 Registered: 01-2003 Posted on Sunday, March 30, 2014 - 04:55 pm:    It would be nice to see an independent study, based on in-service performance. Many times, with best intentions, we are influenced by big companies who get there the fustest with the mostest.