Impact Rated Windows: DP, ASTM, and NOA Explained

Impact rated windows in Florida must carry a Design Pressure (DP) rating, measured in pounds per square foot (psf). DP50 means the unit survives 50 psf of static air pressure without failure. That is not 50 mph — a common and costly misconception. Per ASCE 7 load calculations, DP50 corresponds to roughly 173 mph design wind speed. DP70 corresponds to roughly 205 mph. The higher the DP number, the stronger the unit. Miami-Dade and Broward homeowners typically need at least DP50 for most openings. Larger or taller openings — think floor-to-ceiling glass in a coastal high-rise — may require DP60 or DP70. Your building official determines the minimum based on your home's height, location, and exposure category. Always match the DP rating on the spec sheet to the requirement on your permit drawings. A DP40 window installed where DP50 is required will fail inspection and must be replaced at your cost.

3 different labeling systems appear on Florida spec sheets, and they confuse even experienced buyers. DP (Design Pressure) is the legacy term used in Florida Product Approvals and Miami-Dade NOA certificates. PG (Performance Grade) is the newer AAMA/WDMA term used on many manufacturer cut sheets. For impact-rated products, PG50 and DP50 reference the same 50 psf pressure threshold. The underlying test criteria differ slightly between standards, so they are not always interchangeable for code purposes. Florida's Florida Building Code requires that the product approval reference match the code edition in effect at permit time. When in doubt, ask your installer for the Florida Product Approval number — the FL# — and look it up directly in the state's database. That FL# will list the exact DP value, the test standard, and the approved configurations. Never rely on a marketing brochure number alone.

ASTM E1886 defines exactly how impact products are tested in a laboratory. The test has 2 distinct phases. First, a missile is fired at the glazing (the glass assembly) at a specified speed. Second, the assembly must survive 9,000 cyclic pressure cycles — repeated positive and negative air pulses that simulate a full hurricane's gusting pattern. A window that cracks on the first missile strike fails immediately. A window that survives the missile but leaks air after 4,500 pressure cycles also fails. ASTM E1996 is the companion standard. It defines missile categories A through E, specifying the size and speed of the projectile used in each test. Category C uses a 4.0 lb 2x4 fired at 40 feet per second. Category D uses a heavier 9.0 lb 2x4 fired at 50 feet per second. You can dig deeper into how laminated glass survives these impacts on our impact glass laminated PVB explained page.

Florida has 2 parallel approval tracks for impact rated windows. The Florida Product Approval (FL#) is a statewide certification. It confirms the product meets Florida Building Code minimums and is valid in most of the state. The Miami-Dade Notice of Acceptance (NOA) is a stricter county-level certification. It is the toughest impact certification in the United States. NOA is required for every opening in Miami-Dade County and Broward County — the two HVHZ (High-Velocity Hurricane Zone) counties. If a product carries an NOA, it automatically satisfies the FL# requirement anywhere in Florida. The reverse is not true. An FL#-only window cannot be legally installed in Miami-Dade or Broward without an NOA. Our Broward County impact window permit guide details exactly which documents your building department will request at the job counter. Always verify the NOA number at the Miami-Dade Product Control website before signing a contract.

Florida homeowners insurance carriers require proof of impact rated windows to grant wind mitigation credits. The OIR-B1-1802 form — the standard wind mitigation inspection form — asks the inspector to verify the opening protection rating. A product without a valid NOA or FL# cannot earn full credit, even if the glass looks identical to a certified unit. Credits can reduce your annual premium by 10% to 45% depending on your carrier and coverage tier. Our page on insurance savings with impact windows and wind mitigation breaks down the math by coverage type. Resale value follows the same logic. Appraisers in Miami-Dade and Broward increasingly distinguish between NOA-certified windows and non-certified glass when valuing a home. With 30+ years of direct South Florida experience, SafeGuard has worked through every major hurricane and code update since Andrew — and the documentation requirements have only grown stricter since 1992.

Location drives the minimum specification for impact rated windows more than any other factor. Homes in Miami-Dade and Broward always need NOA-certified, Missile Level D products — full stop. Homes in Palm Beach County or Martin County may qualify for FL#-only, Level C products in inland zones, but coastal parcels often require Level D per the local AHJ. Our best hurricane impact windows buying guide walks through how exposure category (A, B, C, or D per ASCE 7) affects your minimum DP requirement by building height. A single-story home in Coral Springs needs a lower DP than a 4th-floor condo in Aventura facing open water. Verify your parcel's flood zone at the FEMA Flood Map Service Center — coastal A and V zones typically trigger the highest exposure categories and the strictest DP requirements. Getting the spec right before ordering saves weeks of permit delays and thousands in re-order costs.

Every legitimate impact window contractor should hand you 4 specific documents before installation begins. First, the Florida Product Approval (FL#) or Miami-Dade NOA number for the exact product and configuration being installed. Second, the ASTM E1886 laboratory test report number — not a summary, the actual report reference. Third, the DP rating tied to that FL# or NOA, confirming it meets your permit's minimum. Fourth, the missile level category per ASTM E1996 — Level C or D, stated clearly in writing. You can verify contractor licensing at Florida DBPR contractor lookup in under 60 seconds. If an installer cannot produce all 4 documents, that is a serious red flag. Homeowners in Miami-Dade and Broward who skip this step frequently discover non-compliant products at final inspection — triggering costly replacements. SafeGuard includes the DP rating, missile category, NOA or FL# number, and ASTM test report reference on every quote we deliver. Ask any installer you consider for the same paperwork.