Clearance Standard?

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Author Message Ralph Liebing, RA, CSI, CDT Senior Member Username: rliebing Post Number: 1407 Registered: 02-2003 Posted on Thursday, June 20, 2013 - 08:05 am:    Is there a reference standard or industry standard for the clear distance between the frame of windows and storefront construction and the face of the opening wall [jambs and heads]? ken hercenberg Senior Member Username: khercenberg Post Number: 538 Registered: 12-2006 Posted on Thursday, June 20, 2013 - 09:12 am:    Great question. I've never seen a standard, but my rule of thumb is that it's literally the size of a sealant joint. Allowing for fabrication and installation tolerances of the 'masonry opening' (well, that's what it was called when I was young!) and of the fenestration, the annular space should be designed between 3/8 and 1/2 inch (I typically like to show it graphically as a 3/8 inch joint). Of course no designer wants to see a large sealant joint, but even with that dimension shown I've seen fenestrations delivered to sites that had anything from zero clearance to over a one inch gap (thankfully not on the same opening). Nathan Woods, CSI, CCCA, LEED AP Senior Member Username: nwoods Post Number: 536 Registered: 08-2005 Posted on Thursday, June 20, 2013 - 09:25 am:    I don't know. But every architect I've ever known thinks it should be 3/8" maximum and every contractor I've ever met thinks it should be 3/4" minimum. I personally detail the joints at 1/2" and call for a truce. J. Peter Jordan Senior Member Username: jpjordan Post Number: 579 Registered: 05-2004 Posted on Thursday, June 20, 2013 - 10:05 am:    This is directly related to how "square" the openings are. If the openings are not square, the dimension of the sealant joint will vary from 1/8 inch to 1 inch (hopefully that would be the worst case). The best measure of squareness is comparing the dimension of the diagonals. For perfectly square openings, the dimensions are equal. In this case a 1/4- to 3/8-inch clearance should be sufficient. Tolerances based on variation from vertical and from level may not be sufficient and variations on opposite sides of the opening will have a cumulative effect. The tolerance for squareness will be more critical on smaller openings, but it may be that a "squareness tolerance" should be stated. Robert E. Woodburn Senior Member Username: bob_woodburn Post Number: 51 Registered: 11-2010 Posted on Thursday, June 20, 2013 - 10:15 am:    (Written and posted before I saw Peter's post above...) There needs to be enough clearance between the rough opening and frame to allow for shimming. Contractors know how far out of plumb, level and/or square such openings can be, perhaps because tolerances are not strictly enforced. However, tolerances add up. Shouldn't clearances be based on the collective worst case of R.O. tolerances? How do you calculate that? Richard Gonser AIA CSI CCCA SCIP Senior Member Username: rich_gonser Post Number: 43 Registered: 11-2008 Posted on Thursday, June 20, 2013 - 10:36 am:    I do recall that exact issue some years ago and being told that the window manufacturers got together and developed the larger standard. The reason was you can't get the proper shape and adherence to the jamb surface with small dimensions. When the metal would expand or contract, the sealant did not have enough dimension to accommodate the change. I believe you are looking for AAMA 851-09 "Fenestration Sealants Guide for Windows, Window Walls and Curtain Walls". Does anyone have a copy they can share? ken hercenberg Senior Member Username: khercenberg Post Number: 540 Registered: 12-2006 Posted on Friday, June 21, 2013 - 09:53 am:    Copies cost $45 for non-AAMA members. Sharing is probably a copyright violation. Here's the blurb: http://www.aamanet.org/news/2/1/0/all/378/aama-851-09-sealants-guide-issued Richard Gonser AIA CSI CCCA SCIP Senior Member Username: rich_gonser Post Number: 44 Registered: 11-2008 Posted on Friday, June 21, 2013 - 11:44 am:    What I meant was perhaps a relevant quote from the document. Obviously, sending around PDF copies is a copyright issue. Paul Gerber Senior Member Username: paulgerber Post Number: 159 Registered: 04-2010 Posted on Friday, July 05, 2013 - 11:19 am:    WOW!! Non-AAMA members who could help make their members lives easier get "raped" for 3x pricing compared to members!! Now that's a marketing campaign to increase membership for ya! *rolls eyes* "Oh I want to join this industry organization!!" I can understand a 25% to 50% premium for non-members, but 300% makes me feel violated! "Would you like lubricant with your order?" Ride it like you stole it!!! Alan Mays, AIA Senior Member Username: amays Post Number: 125 Registered: 02-2003 Posted on Friday, July 05, 2013 - 12:03 pm:    Sadly, Paul, this is where our industry is heading. Everything costs money. I also used to be able to get Gypsum Association's fire resistance guide for free if I downloaded it as a PDF. Alas, not so anymore. Same with the TCNA. This has and still is a growing issue. Everybody wants money. That is accept the owners/clients that want it for free. What can we actually do to stop this money drain? I actually think the "or else" letters talked about in a different thread may be a start. While it was about a different issue with manufacturers, it does pose a possible solution. Another way is to instill these costs directly to the clients and owners. Charge the clients a direct cost for standards and codes. I am sure there are other ways. The thing is that we should directly itemize it so that they see it. Similar to the shipping charges we are always see when buying something. This also holds true with the building codes. Why do we have to pay for them when they are required codes? Some states are now being challenged and changing their ways. California is an example. They provide the CBC on line for free. John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 1514 Registered: 03-2002 Posted on Friday, July 05, 2013 - 12:17 pm:    Not to particularly defend AAMA's pricing strategy, but if I recall their membership cost is relatively low, and at the same time, it is really worth it to have their various technical manuals in one's library. BTW, I am well aware of the cost of maintaining a good technical library, but I cannot see any way to be a good specifier without it. Richard Gonser AIA CSI CCCA SCIP Senior Member Username: rich_gonser Post Number: 45 Registered: 11-2008 Posted on Friday, July 05, 2013 - 02:45 pm:    Your manufacturer's product rep should have a copy that they can let you use. I have always gotten the TCNA manuals from reps.