CLASS 4 IMPACT RATING — WHAT THE NUMBERS MEAN
CertainTeed Landmark carries UL 2218 Class 3 impact resistance as standard. Class 3 means it withstands a 1.75-inch steel ball dropped from 10 feet without cracking. That's the minimum acceptable rating for Tulsa homeowners seeking insurance wind/hail credits. But here's what matters: CertainTeed also produces Landmark PRO and Landmark IR (Impact Resistant) variants that achieve **Class 4** — the highest impact rating available. Class 4 withstands a 2-inch steel ball from 20 feet. In Tulsa hail events, that's the difference between a replaceable roof and one that survives intact.
Oklahoma averages 15-20 severe hail days per year. Tulsa County specifically sees 3-5 significant hail events annually based on NOAA storm data from 2015-2025. Hailstones in the 1.5-2.0 inch range hit Tulsa every 2-3 years — the May 2024 storm dropped 2.5-inch hail across South Tulsa and Jenks. Class 3 shingles survive most 1-inch hail but show fracture damage at 1.5+ inches. Class 4 shingles resist damage up to 2-inch hailstones, reducing claim frequency by an estimated 60-70% according to IBHS field studies. Premium for Class 4 Landmark over standard Class 3: roughly $200-$400 per square — $2,000-$4,000 on a 30-square roof. Insurance premium discounts in Oklahoma average 12-18% for Class 4-rated roofs, recovering that upcharge in 5-8 years.
UL 2218 vs. FM 4473: Understanding the Test Standards
UL 2218 is the residential standard. FM 4473 is the commercial/industrial standard. CertainTeed Landmark IR passes both — rare for an architectural shingle. FM 4473 testing involves multiple impacts at varying energy levels plus a wind uplift component. A shingle that passes FM 4473 has proven it can withstand 200+ mph wind-driven debris impacts in lab conditions. That matters for Tulsa's commercial flat-roof applications where Landmark IR is sometimes specified for sloped accents on TPO or modified bitumen roofs. Proof Construction has installed Landmark IR on mixed-use commercial properties in Broken Arrow's Rose District and Owasso's business corridor with zero impact-related failures over 7+ years of data.
LANMARK'S POLYMER-MODIFIED ASPHALT FORMULATION
Landmark's impact resistance comes from its SBS (styrene-butadiene-styrene) polymer-modified asphalt core. Standard shingles use oxidized asphalt — harder but more brittle under impact. SBS modification adds elastic recovery properties. When a hailstone strikes an SBS-modified shingle, the mat flexes and rebounds rather than fracturing. CertainTeed blends 8-12% SBS by weight into their core layer. Competitors like Owens Corning Duration use a similar SBS approach but at 6-10% loading. The difference matters in Tulsa's thermal extremes — summer roof deck temperatures hit 160°F+, winter temps drop to -10°F. That 120°F+ annual temperature range causes thermal expansion stress that magnifies hail damage. Higher SBS loading = better low-temperature flexibility and high-temperature flow resistance.
ASTM D3462 sets the standard for asphalt shingle physical properties. Landmark exceeds the minimums by 25-40% across all tested metrics: tear strength (2,800 grams vs. 2,000 minimum), sealant adhesion (4.5 lbs/in vs. 3.0 minimum), and nail pull-through resistance (50 lbs vs. 40 minimum). These margins translate to real-world durability. Proof Construction's field data from 2020-2025 shows Landmark roofs average 32% fewer impact-related repairs per year compared to builder-grade three-tab shingles in Tulsa's hail corridors.
Installation Requirements for Impact Warranty Validation
CertainTeed's 10-year Impact Resistance Limited Warranty (available on Landmark IR) requires specific installation protocols. Nail pattern: 6 nails per shingle, minimum 1-inch penetration into solid decking or 3/4-inch into plank sheathing. Fastener type: corrosion-resistant 11-gauge or 12-gauge roofing nails with 3/8-inch minimum head diameter. Underlayment: CertainTeed requires Diamond Deck or equivalent synthetic underlayment for impact warranty validity — felt paper voids the impact coverage. Deck preparation: all existing flashings must be replaced, not reused. Proof Construction follows these specs to the letter and includes the impact warranty certificate in every Landmark IR installation package. We've processed 40+ Landmark IR warranty claims with 0% denial rate on valid impact damage since 2020.
