Years ago, glass doors were commonly locked with a deadlock in the bottom rail. Many of these doors are still in use, but in order to comply with current codes, I don’t recommend the use of a bottom rail deadlock on most new projects.
Assuming that the glass door is a required egress door and/or on an accessible route, the operating hardware must be mounted between 34″ and 48″ above the finished floor per the IBC and NFPA 101. The 1994 version of the ADAAG requires operating hardware to be mounted below 48″ (no low limit is specified), but the proposed ADAAG and ICC/ANSI A117.1 both require the same 34″-48″ range. In Massachusetts, the operating hardware must be mounted between 36″ and 48″ above the finished floor per 521 CMR.
In some cases, the code official will allow a bottom rail deadlock to be used “after hours” because of the exception for “locks used only for security purposes”, but because of issues I’ve had in the past I tend to err on the side of caution. I typically use glass door panic devices or deadbolts made by Blumcraft or CR Laurence, a center housing with a mortise lockset, or electrified hardware.
Here’s the text from the IBC 2009, 2006, 2003:
1008.1.9.2 Hardware height. Door handles, pulls, latches, locks and other operating devices shall be installed 34 inches (864 mm) minimum and 48 inches (1219 mm) maximum above the finished floor. Locks used only for security purposes and not used for normal operation are permitted at any height.
And NFPA 101 2006, 2009:
184.108.40.206.9.1 The releasing mechanism for any latch other than existing installations shall be located not less than 34 in. (865 mm), and not more than 48 in. (1220 mm), above the finished floor.
ICC/ANSI A117.1 2003 (same text in proposed ADAAG 404.2.7):
404.2.6 Door Hardware. …Operable parts of such hardware shall be 34″ inches minimum and 48″ maximum above the floor…
Massachusetts 521 CMR:
26.11.2 Height: Hand-operated door opening hardware shall be located 36 inches to 48 inches (36″ to 48″ = 914mm to 1219mm) above the floor. See Fig. 26i (below).
Figure 26i from MA 521 CMR: