Hurricane preparation for rooftop mechanical plant

How is rooftop HVAC equipment actually secured to a building?

Through a continuous load path: the unit is positively fastened to a curb, rail or dunnage frame, that support is fastened to the roof structure, and the structure carries the load. Weight is not an attachment method; nor is friction.

In practice, a prefabricated curb matched to the unit's footprint, fastened into structural members rather than deck alone, with the unit bolted where the manufacturer nominates. For anchors set to the membrane rather than through it, FM Approvals publishes FM 4481, Anchors for Roof Mounted Equipment, issued 22 July 2022.

Outside the High-Velocity Hurricane Zone, Florida Building Code Section 1510.10 requires roof-mounted mechanical units to sit on curbs raised at least 8 inches above the roof. Inside the HVHZ, Section 1522.2 is blunter: all rooftop equipment and supports shall be secured to the structure per the loading requirements of Chapter 16, and wood sleepers are not permitted.

The loads come from ASCE 7, which the 8th Edition (2023) Code adopted at ASCE 7-22 and the 9th Edition carries forward from 31 December 2026. Rooftop equipment is treated at Section 29.4.1, yielding a lateral force and a simultaneous uplift. ASCE 7-16 removed the old 60-foot height cut-off, so uplift now applies at any building height.

Does a unit set down in 1998 and never reassessed still comply?

Almost certainly not against today's numbers, and in most cases it does not have to be: existing equipment is not retroactively required to meet the current code. Whether the attachment will hold is another question.

The code reaches old plant at replacement, at relocation, when the roof beneath it is replaced, and on any permitted work. Section 553.844(5), Florida Statutes, settles the roofing side: where 25 percent or more of a roof permitted under the 2007 code or later is repaired, only the repaired portion must meet current code.

So the legal exposure is usually small; the physical exposure is not. The commonest finding is not an old unit but an undocumented changeout — a newer unit on an older curb built for a different footprint, shimmed and sealed, with no calculation and no permit record.

What separates storm damage from deferred maintenance in a claim?

Standard commercial property forms cover direct physical loss from windstorm but exclude wear and tear, rust, corrosion, decay and deterioration. So the argument after a hurricane is rarely whether the storm happened. It is which part of the damage the storm caused, decided on evidence of condition before the wind arrived.

Three patterns account for most disputes. A coil with eight years of chloride pitting is damaged further by debris, and the insurer apportions. A curb whose anchors had already corroded fails below the design load, and the insurer puts the failure in the fixing. Interior water enters, and coverage turns on whether wind first opened the envelope — the windstorm and hail peril in the basic form excludes interior damage from rain unless wind or hail first damages the roof or walls.

A dated April inspection changes that: the deferred-maintenance narrative has to be argued against a document rather than asserted into a vacuum. Two things then decide the number. Depreciation, since a unit at the end of its life settles on actual cash value terms unless replacement cost coverage says otherwise. And code upgrade, since a replacement must be anchored to current loads and, in the HVHZ, raised to the clearances in Table 1522.3 — ordinance or law coverage decides who pays that.

How do you restart rooftop equipment after a hurricane?

Document first, inspect second, dry and test third, energise last. A unit that has been flooded or salt-sprayed is not switched on to see whether it works. That converts a repairable claim into a replacement, and puts someone in front of equipment whose insulation may no longer be insulation.

Photograph before anything is touched. Wide shots that place the damage in the building, then each unit, then the attachment detail, then the debris where it landed. Debris moved before it is photographed is debris whose origin can be argued.

Then the clock, which runs under Sections 627.70132 and 627.70131, Florida Statutes, set out below. A governor's declaration of a state of emergency does not by itself toll those deadlines — only an order from the Office of Insurance Regulation does.

Electrical before mechanical. NEMA CS 70006-2026, Evaluating Water-Damaged Electrical Equipment, formerly NEMA GD 1, lists water-damaged motors, moulded-case circuit breakers, switches and fuses for replacement rather than reconditioning, and notes that salt water residue is both corrosive and conductive. Insulation resistance on windings is measured, not judged by eye.

Then the mechanical side. Coils and cabinets rinsed with potable water to carry the chloride off before it dries in place; drain pans cleared, bearings, belts and blower wheels inspected.

A refrigerant circuit is a repair, not a top-up. Under EPA's Section 608 rules at 40 CFR Part 82, Subpart F, appliances holding 50 pounds or more of regulated refrigerant must have leaks repaired once the annual leak rate passes the trigger — 10 percent for comfort cooling, 20 for commercial refrigeration, 30 for industrial process — within thirty days, with verification tests.

Energise last, with a written note of who inspected what and when, and then photograph the unit running.