A glass panel fails on the 22nd floor. The manager's assumption is that a glazier turns up, takes the old one out and puts a new one in. What actually follows is a sequence with a long lead time in the middle of it, and the decisions made in the first day determine how the rest goes.
Why the glass takes weeks
Architectural glass on a commercial building is not stock. A replacement unit is usually fabricated to order, and the specification has more variables than most people expect:
- Make-up — monolithic, laminated, or insulated glass unit, and if insulated, the cavity dimension and gas fill
- Tempered or heat-strengthened, which is a structural decision, not a preference
- Coating — low-E type and which surface it sits on. Get the surface wrong and the unit looks different from its neighbours
- Tint and colour — and whether the existing glass has weathered away from its original colour
- Exact dimensions and edge condition, measured from the actual opening
Fabrication, tempering and shipping take what they take. What you can control is not starting that clock late because someone measured wrong.
The most expensive mistake in glass replacement is a re-order. Getting the specification right on day one is worth more than any speed the contractor can offer afterwards.
Why the frame matters more than the pane
Before ordering anything, the frame and the fixings need looking at.
If the unit failed because of impact, the frame is probably fine. If it failed for another reason — thermal stress, a spontaneous inclusion failure, building movement, or corrosion at the fixings — then the same conditions are still there, and a new pane goes into a compromised opening.
Things worth confirming while the opening is empty:
- Gasket and setting-block condition
- Corrosion at fixings and at the perimeter
- Whether the frame has moved or racked
- Whether adjacent units show early signs of the same problem
If several panes came from the same batch and one has failed spontaneously, the neighbours are worth inspecting rather than waiting on.
The interim: the part that costs the most if skipped
Between the failure and the new unit arriving there is an opening in the building envelope, and it needs closing that day.
An emergency board-up stops the falling-glass hazard, closes the path for wind and water, and makes the unit or floor usable again. The sequence for that first day — controlling the ground before touching the glass, clearing the remaining panes under control, then fitting the board-up — is covered in the first four hours after a glass panel fails.
The remaining glass in the frame is the part people underestimate. Tempered glass that has failed often holds in place and then releases in sheets as it flexes with wind. Clearing it deliberately, into containment, is not tidiness. It is removing something on an unknown timer.
Access: why the method decides the schedule
Getting a heavy, fragile, precisely-sized unit to the 22nd floor is its own problem.
Through the building. Sometimes possible, often not — the unit does not fit the service elevator or turn the corridor corner, and moving it inside means protecting finishes and closing routes.
By crane. Needs lot or street space for outriggers, a closure, a permit and a reach that gets to the right elevation. On a beachfront tower or a downtown lot on the property line, frequently impossible.
Up the outside, on rope. The unit is rigged and raised on the exterior, handled at both ends, with no interior involvement and no street closure. This is also how the failed unit comes down.
That last option is why glass work on occupied towers is so often scheduled overnight — see why façade work happens at night — and it is a real case on our own jobs: a sloped glass canopy replaced overnight in Downtown Miami where no lift could sit on the surface and the entrance below could not close during business hours.
What to have ready when you call
- Floor, elevation and unit number.
- Photographs of the failure and the frame, including the break pattern.
- Whether glass has already fallen, and what is below.
- The original glazing specification, if the building has it. This alone can remove days.
- Whether roof anchorages exist and are certified. Without written certification, exterior access cannot legally begin — see what IRATA and SPRAT certification actually mean.
Frequently asked
Why can't you just put a new pane in tomorrow?
Because architectural glass is fabricated to order. Make-up, coating, tint, temper and exact dimensions are building-specific, and tempering and shipping take time. What can happen tomorrow — and should — is securing the opening.
Why did the glass break with nothing hitting it?
Tempered glass can fail spontaneously from a nickel sulfide inclusion introduced during manufacture, which expands over time and eventually breaks the pane, often years later and often on a hot day. Thermal stress and building movement are other causes. Impact is only one explanation.
Should we inspect the other panels?
If the failure was spontaneous rather than impact, yes. Panels from the same batch share the same manufacturing history. It is worth a close-range look at the adjacent units while the crew is already on the elevation.
Is board-up really necessary if the replacement is only a few weeks away?
An open envelope on a high-rise changes airflow on the floor, admits water at the next rain, and can leave a unit unusable. In hurricane season a few weeks can include a named storm. The board-up is the cheap part.
Sources
- OSHA — walking-working surfaces and personal fall protection systems, general industry: osha.gov
- IRATA International — International Code of Practice: irata.org
- Glass fabricators and glazing system manufacturers publish specification and failure-mode guidance; the specification for your building is the authority for your building.
Skyhanger II Corp handles commercial glass installation and replacement on South Florida high-rises, including emergency clearing and board-up, 24/7.
(954) 609-7870 · General@skyhanger2.com