By Dan Cahill
After six decades of repairing, maintaining, and replacing commercial roofs across Southern California, we know exactly how each system performs once the last crew has packed up. Built‑up asphalt, rubber‑modified bitumen, the latest single‑ply plastics, classic metal panels, mission‑style tiles, and modern restorative coatings all deliver distinct blends of cost, durability, and risk—and those trade‑offs become painfully apparent when a roof ages past its honeymoon phase.
Drawing on thousands of service calls and forensic inspections, we cut through marketing claims to show where each membrane excels, where it falls short, and what that means for a roof that must protect tenants, equipment, and balance sheets for decades.
Built-Up Roofing (BUR)
Built‑up roofing (BUR) is one of the oldest flat‑roof assemblies in use. Crews still wheel out a tar kettle, mopping hot asphalt between successive rolled layers—“plies”—to create the system. A base sheet goes down first, followed by one, two, or occasionally three fiberglass plies, and a protective cap sheet seals the surface, literally “building up” the roof. BUR dominated commercial roofs across North America 25–30 years ago, from Maine to Southern California, much like manual gearboxes once ruled the road before automatics became standard. It remains common, though it is no longer the default choice.
The draw is its modest upfront cost without bargain‑basement quality. Depending on the specification, warranties run from five years (albeit rare) to about twenty years. Field experience shows that once the warranty expires, substantial repairs—or a complete replacement—are usually close behind; few BUR roofs outperform their guarantee by more than a handful of years.
Newer membrane technologies often deliver meaningful service life well past their warranty period, so when the cost per year of actual performance is calculated—not just warranty coverage—BUR may prove less economical over the long term.
Modified Bitumen Roofing
Modified bitumen (MB) is the logical successor to classic built‑up roofing. In the 1970s and ’80s, manufacturers began blending traditional asphalt with rubber and plastic polymers, creating a far more elastic and tear‑resistant membrane than its predecessors. That elasticity is critical on Southern California commercial roofs, which expand under daytime heat and contract when temperatures drop at night. A conventional built‑up roof can fatigue and crack at stress points—90‑degree transitions, HVAC curbs, parapet walls—after years of this daily push‑and‑pull. The polymer additives in an MB sheet absorb those movements, dramatically reducing the risk of splits and leaks in vulnerable areas.
Construction is straightforward: a polyester or fiberglass reinforcing mat is saturated with rubber‑modified asphalt and then factory‑finished with either a granular or smooth surface. The result is a single‑ply sheet that performs better through temperature swings, endures foot traffic, and weathers more evenly in later years. Interestingly, the formulation began in Italy as an impermeable pond liner before its advantages in roofing were recognized.
Warranties typically run 12–20 years, yet field data show well‑installed MB roofs delivering 25–30 years—and counting—of leak‑free service. SBR Roofing maintains several modified roofs that are past their original 12‑year warranty and still performing after three decades. That extra runway matters: every deferred re‑roof avoids not only capital expense but also the operational disruption tenants dread in restaurants, hospitals, schools, and other noise‑sensitive facilities.
The upfront cost has narrowed over time. On comparable 20‑year specifications, an MB roof is now about 10 percent more than a built‑up system. When that modest premium buys an additional decade—or more—of service life, the life‑cycle economics favor modified bitumen. In short, you pay a little extra today to avoid a much larger re‑roofing bill (and headache) tomorrow.
TPO
Thermoplastic polyolefin (TPO) appeared in the 1990s as the next leap in single‑ply membranes. Instead of reinforcing asphalt, manufacturers extrude a plastic sheet in wide rolls—5 × 100 ft and 10 × 100 ft are common—so crews weld far fewer seams than they do with 3 × 33 ft asphalt plies. At 45 – 80 mils thick, the membrane is thin, light, and quick to install, placing minimal dead load on the structure. Warranties run for 15–20 years.
The caution flag is the chemistry: TPO is still a work in progress. Early formulations failed inside their warranty periods—leaks that required large‑scale repairs or full replacement—so every major manufacturer kept “tinkering with the recipe.” Industry‑wide, the product has been reformulated six or seven times; the sheet sold today has only a decade of field history. In other words, a 20‑year warranty often covers a membrane with 10 years of real‑world data, and defects in the previous version drove each reformulation.
Because TPO is inexpensive, it looks appealing at bid time, yet roofing is a long‑term asset, not a gadget you swap out every few years. Clients who took earlier versions sometimes feel like guinea pigs. For that reason, SBR Roofing rarely recommends TPO to legacy‑minded owners. The material may eventually deliver on its promise, but the proof of decades‑long performance remains pending.
EPDM
Ethylene Propylene Diene Monomer (EPDM) is a black, rubber‑based, single‑ply membrane extruded in long, relatively narrow sheets. Its inherent elasticity is much higher than that of light‑colored plastics like TPO, allowing it to stretch and rebound through the wide seasonal temperature swings common in the Midwest and other snow‑belt regions. Buildings in those climates expand during hot, humid summers and contract during frigid winters; EPDM absorbs that movement without splitting, which is why decades of field use have given it a reputation for reliability and minimal manufacturing defects.
Southern California is a different story. The membrane’s dark surface soaks up heat, driving rooftop temperatures far higher than ambient air. For that reason, EPDM installations here are rare; in more than 25 years, we have encountered only a handful. In short, EPDM is an excellent choice where cold‑weather performance is paramount, but the sun‑baked West has never been its natural market.
Metal Roofing Systems
Metal roofing encompasses several panel styles that balance cost, appearance, and performance:
- Corrugated Panels: The familiar wavy aluminum or galvanized steel sheets on warehouses, barns, and budget‑driven industrial buildings. Fast to install and inexpensive, they deliver bare‑bones weather protection when aesthetics are secondary.
- Standing‑Seam Panels: Long, flat pans joined by raised, concealed‑fastener ribs. Powder‑coated finishes resist coastal corrosion, and the sleek surface sheds snow quickly in mountain towns such as Big Bear. Materials and labor run high, but many architects specify standing seam for its clean, contemporary look; it is now the second‑most common metal option we encounter.
- Stamped Metal Tiles and Shingles: Factory‑formed panels that imitate traditional shakes or tiles. Once more widespread, they have become niche products offered by boutique manufacturers. Most mainstream brands now replicate those shapes with non‑metal composites to sidestep metal’s higher material cost.
Southern California still sees basic corrugated roofs on cost‑conscious facilities, while standing‑seam and stamped profiles appear on projects where corrosion resistance, snow management, or modern curb appeal outweigh the price premium.
Tile Roofing
Visitors quickly notice the red, semi‑cylindrical tiles topping many homes. Classic clay tiles—kiln‑fired, brittle, and centuries-old in design—set that visual standard. Concrete tiles arrived later, offering similar looks with better resistance to foot traffic and impact. Both products have expanded beyond terracotta red; modern palettes span virtually every color family to suit contemporary architecture.
Restorative Roof Coatings
Restorative coatings are applied directly over an existing roof—whether built‑up, modified bitumen, TPO, or another membrane—to renew the surface and extend its service life. Rather than building a roof from the deck up, the coating acts as a protective top layer, sealing minor cracks, boosting UV resistance, and improving waterproofing. In other words, a coating is a maintenance strategy: it preserves and upgrades the roof you already have instead of replacing it with a brand-new system.
Conclusion
After weighing the real‑world strengths and weaknesses of every major system, we return to a simple principle: the best roof is the one that delivers the lowest total cost of ownership—purchase price, maintenance, energy use, and inevitable repairs—over the full span of its service life. Sometimes, that points to proven modified bitumen, other times to a high‑build coating that squeezes extra years out of sound insulation, or to a premium standing‑seam metal assembly where aesthetics, longevity, and solar readiness converge.
Whatever the solution, we stand behind it for the long haul because our reputation rides on every square foot we install and maintain. Discover why top businesses trust SBR Roofing for expert roof replacement services—click to learn more.
Author Bio
Dan Cahill embarked on his journey in 2001, accumulating over 23 years of experience in the commercial roofing field. The original owner of SBR Roofing extended a trial opportunity in 2001, coinciding with the dot-com bubble burst. The proposition was simple: give it a year, see if it suits you, and if not, no hard feelings. Surprisingly, Dan found himself sticking around. Fast-forward over two decades, and he continues to thrive in the field.
With a background in sales, Dan discovered a passion for the dynamics of salesmanship, particularly in the freedom it offered from the confines of a desk. The opportunity to engage with people, navigate various situations, and even climb up on roofs appealed to him. This intriguing experience kept Dan hooked, prompting him to stay the course, eventually becoming a leader in the roofing industry.
