Wind Load Calculation Letters — ASCE 7-22 for Residential and Light Commercial

Wind load reports are the backbone of coastal and hurricane-region construction. When an architect, contractor, or product manufacturer needs to prove that a roofing system, window, structural component, or cladding resists the site-specific design wind pressure, a PE-sealed wind calculation report is the deliverable.

We write these to ASCE 7-22 — the current edition referenced by the 2024 IBC and adopted (with amendments) across most hurricane-prone jurisdictions. Older-edition reports (ASCE 7-16, 7-10) are still issued for projects permitted under those code cycles.

What a wind calculation letter contains

Risk Category. Category I, II, III, or IV based on occupancy per ASCE 7-22 Table 1.5-1. Most single-family residential falls in Category II.

Basic wind speed. Looked up from the ASCE 7 Hazard Tool for the exact project coordinates, at the applicable Risk Category. In Florida, these run from 140 mph inland to 180 mph in the Keys.

Exposure category. B (suburban), C (open terrain), or D (water-facing). Exposure D along the coast generates markedly higher pressures.

Enclosure classification. Enclosed, partially enclosed, or open — with Florida’s High-Velocity Hurricane Zone (HVHZ) requiring impact protection or partially-enclosed classification.

Mean roof height and geometry. Each zone of the building envelope sees different pressures.

Component and Cladding (C&C) pressures. Broken out by zone (corners, edges, field), for both the positive and negative surfaces, with effective wind area considerations.

Main Wind Force Resisting System (MWFRS) pressures. For the overall structural analysis.

Where these reports get used

Roofing permit applications. Many Florida jurisdictions require an attached wind calculation for re-roof permits over a certain square footage or in HVHZ.

Window and door installations. The design wind pressure at each opening determines which NOA-approved products are acceptable. The calculation letter supports the product selection. See our Florida window installation case study for a full example.

Screen enclosures and pool cages. The wind analysis for an aluminum enclosure is usually prepared alongside the structural design. See our pool enclosure article.

Product approval submissions. Manufacturers submitting for NOA or FL product approval rely on wind pressure calculations prepared by a licensed PE.

Insurance mitigation credits. Some carriers recognize PE-documented wind-mitigation features on a site-specific basis.

Paired with forensic work

When wind load calculations are prepared in the context of a damage claim — “did this roof fail because the wind exceeded its design capacity?” — the analysis usually pairs with a forensic investigation from our colleagues at HurricaneInspections.com. Their forensic engineering approach documents what the winds actually were, what the damage patterns show, and whether the failure was consistent with a design-event or with a sub-design event.

If you need a wind calculation report for a permit, an insurance claim, or a product submission, reach out. We quote these hourly and most reports close within 3–5 business days.