| Author |
Message |
David J. Wyatt, CDT
Senior Member
Username: david_j_wyatt_cdt
Post Number: 161
Registered: 03-2011
| | Posted on Thursday, January 12, 2017 - 11:42 am: |    |
I specified tempered mirrors for a health/fitness facility. Post-award, the CM wants to use mirror safety tape with non-tempered mirror glass in lieu of the specified products. Does anyone have any experience with outcomes on this? |
anon (Unregistered Guest)
Unregistered guest
| | Posted on Thursday, January 12, 2017 - 11:46 am: | |
Why did you specify tempered mirrors? If the mirrors are installed over solid backing (i.e. a wall) code allows annealed glass to be used, which is less expensive and also higher visual quality. |
J. Peter Jordan
Senior Member
Username: jpjordan
Post Number: 928
Registered: 05-2004
| | Posted on Thursday, January 12, 2017 - 12:02 pm: | |
I did find the exceptioni in the IBC which allows this (see 2406.1 Exception); however, I am not at all certain that mirrors in a health/fitness facility are installed with a "continuous backing." I believe these are usually applied with spots of adhesive. If the mirror were to be broken, some if it could still come down in dangerous shards.
I am curious about the "mirror safety tape."
J. Peter Jordan, FCSI, AIA, CCS, LEED AP, SCIP
|
anon (Unregistered Guest)
Unregistered guest
| | Posted on Thursday, January 12, 2017 - 12:12 pm: | |
Reading the Commentary in the IBC about this exception may change your mind. Globs of adhesive do not make the shards of glass any more dangerous. |
Edward J Dueppen, RA, CSI, CCS, LEED AP
Senior Member
Username: edueppen
Post Number: 33
Registered: 08-2013
| | Posted on Thursday, January 12, 2017 - 03:20 pm: | |
Tempering mirrors creates visual distortion. I recommend the use an applied safety film across the entire back of an annealed mirror. (I have never heard of "tape" and would not permit it unless it was wide enough to cover the entire mirror back) |
John Hunter
Senior Member
Username: johnhunter
Post Number: 143
Registered: 12-2005
| | Posted on Thursday, January 12, 2017 - 05:16 pm: | |
We've used film-backed safety mirrors (Guardian "Ultra Mirror") and laminated mirrors with the outer lite 3mm Mirror Select, the inner lite 3mm clear annealed glass and an 0.30 inc polyvinylbutyral interlayer. As Edward notes, tempered mirrors will have visual distortion that will likely be unacceptable to the end users. |
Bill Coady CSI, CCPR
Senior Member
Username: billcoady
Post Number: 31
Registered: 06-2006
| | Posted on Thursday, January 12, 2017 - 09:50 pm: | |
Truth in lending comment...My company, Guardian Glass, manufacturers mirror. I'm not trying to sell any of the readers on using our mirror or products. My comments apply to mirror generically.
Tempered mirror looks like a funny house mirror. Over the years I've successfully convinced all but one facility owner to not use tempered mirror. That owner regretted their decision.
Category II Vinyl Back Tape that is typically used on mirrored wardrobe doors is a possible solution if you are concerned with the possibility of glass shards. While there are a number of manufacturers of this material, one is Shurtape at www.shurtape.com. They make SS 501 Shatterstop vinyl tape for this type of application. If you use vinyl back tape mastic application won't work. It won't stick to the tape. Again, I'm not trying to sell anyone on any product but a discussion like this doesn't do much good if specific options are mentioned.
Another option and arguably the safest and most secure, as John Hunter mentions, although not used as often and at a price premium is to laminate the mirror.
FYI...The Glass Industry of North America (GANA) recommends mechanical fastening of mirrors even if you do use mastic. They have info on this in the GANA Glazing Manual.
You should ensure that the mirror in the gym is installed on a flat GWB or other continuous backing. That backing should be flat also. Mirror, even 6mm (1/4") will follow the variances of the backing which can contribute to distortion issues. Not as bad as tempered mirror but it can be an owner objection.
In closing, I believe most mirrors in gyms are annealed, without vinyl back, and installed with mechanical fasteners (clips or channels) and mastic.
What does the glazing sub-contractor say? I'm assuming they are suggesting the vinyl back option. Not a bad idea. |
Sheldon Wolfe
Senior Member
Username: sheldon_wolfe
Post Number: 947
Registered: 01-2003
| | Posted on Thursday, January 12, 2017 - 10:48 pm: | |
We specify a film on the back of mirrors. Could be the same stuff used on wired glass.
http://bit.ly/2iqoYZH
https://youtu.be/96x2tO9Xuxw |
Edward J Dueppen, RA, CSI, CCS, LEED AP
Senior Member
Username: edueppen
Post Number: 34
Registered: 08-2013
| | Posted on Friday, January 13, 2017 - 08:46 am: | |
Bill - as always, I appreciate your insider point of view.
CR Laurence, and possibly others, have mirror safety film backings that do work with mounting mastics.
http://bit.ly/2jEhZdB
But be sure to read the "Note" indicating that only certain mastics are compatible with the film. |
David J. Wyatt, CDT
Senior Member
Username: david_j_wyatt_cdt
Post Number: 166
Registered: 03-2011
| | Posted on Monday, January 23, 2017 - 02:21 pm: | |
Thank you, everyone. Your recommendations all go in the same general direction, and they have been helpful in raising my awareness. I carried the concept of tempered glass over from the Division 10 specification for smaller framed toilet room mirrors. This is where I went wrong. The building code should be one of the first resources a specifier should rely on.
The term "tape" (see Edward's link), is misleading. In my revised specifications, I am referring to the product generically as "safety backing" then identifying the CRL product as an acceptable product.
Again, thank you 4specs correspondents. |
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