Insulation, Cover Board and Slope to Drain
A new membrane is only as flat and as dry as what it sits on. We replace wet or crushed insulation instead of covering it, add a cover board where the system calls for one, and use tapered insulation to build slope toward the drains so water leaves the roof and does not sit in a low spot. Ponding ages a sheet quickly, and it hides punctures and open laps under a film of dirt, so correcting the fall during replacement is one of the most useful decisions on the job.
Penetrations and drains get the same attention. Every pipe, curb and drain body is rebuilt with its own flashing, sealed and terminated so that it can be inspected later. Scupper boxes and sheet metal are hand-formed to the opening in front of us, not ordered in a catalog size and forced to fit. That fit and finish decides whether the roof still reads as tight after many seasons of afternoon heat pulling the metal one way and the night pulling it back.
Cool Roof Rules and Class A Assemblies
California's energy code sets the surface of a replacement roof before we choose a product. The 2025 California Energy Code requires low-slope nonresidential roofing to reach an aged solar reflectance of 0.63 and a thermal emittance of 0.75, or a solar reflectance index of 75, when the roof is new or when the work covers more than 50 percent of the roof or 2,000 square feet, whichever is smaller. A white TPO roof system or a PVC sheet can meet that, and we confirm the aged values on the product data before anything is ordered.
Fire rules add a second layer near the foothills. In a Very High Fire Hazard Severity Zone, the state wildland-urban interface rules call for a Class A roof covering wherever more than 50 percent of an existing roof is replaced in a year, and Chapter 7A judges the whole assembly of covering, underlayment and deck. Pasadena's mapped zones lie generally in the Arroyo Seco, west and north of the 210 freeway, and in upper Hastings Ranch, so a reroof in upper Hastings Ranch, part of East Pasadena, is specified for embers as well as reflectance.
Sequencing Over Occupied Floors
Many buildings here are working buildings. The historic brick-facade storefronts of Old Pasadena have tech companies and small offices on the upper floors above street-level retail and restaurants, and a medical or campus building cannot close because its roof is coming off. We schedule noisy tear-off, crane lifts and hot work around tenant hours, protect entries and air intakes, and keep a single point of contact for the property manager from the first day to the last.
Equipment gets planned early. Rooftop units are lifted or raised on new curbs so the membrane runs cleanly beneath them instead of being cut around their legs, and tenant-owned equipment is coordinated well ahead of the lift. The approach for reroofing an occupied building is the same whether the roof covers one tenant or twenty.
Cost and Schedule Drivers
Price on a replacement moves with a short list of things we can name. The roof area and the number of penetrations; the condition of the deck once the old roof is off; how much tapered insulation it takes to correct the fall; the system chosen; the height and access for staging; and the amount of sheet metal at edges, copings and scuppers. A large, plain roof with few details prices differently from a small roof on a masonry building with a long parapet, and we walk through the difference line by line.
Schedule follows the same drivers, plus weather and tenant limits. We would rather give an honest window with the unknowns named than promise a date and trim the details to meet it. When the insulation is still dry, a recover over the existing roof may be a lower-disruption path, and an infrared moisture survey tells us which path the building actually allows before anyone commits to a scope.
Commercial Roofing Questions
How do I know whether to replace the roof or keep repairing it?
The deciding factor is how much of the insulation is wet. A roof with isolated leaks and dry insulation can usually be repaired or recovered. Once moisture has spread under the membrane, repairs only move the problem to the next weak spot. We take core samples and, on larger roofs, run a survey, then put the cost of continued repair next to the cost of replacement so the choice stays with you.
Can the roof be replaced while tenants stay in the building?
Yes. Access and noise tolerance on the floors below set the limits. We phase the tear-off, dry in every section by the end of the day, and coordinate lifts and hot work with the property manager. Floors directly under active work may need advance notice, and we settle that with you before the first section of old roof comes off.
Does a new roof have to meet the cool roof requirement?
Yes, once the work passes a certain size. Under the 2025 California Energy Code, new nonresidential low-slope roofs and alterations covering more than 50 percent of the roof or 2,000 square feet, whichever is smaller, must reach the aged reflectance and emittance values. A small repair usually falls below that line. A full replacement does not.
What time of year is best for a tear-off in Pasadena?
Rain risk set against heat drives the choice. The long dry summer keeps an open roof safe, but Pasadena has recorded 113 F in June, so we move adhesive work and heavy lifting to the cooler morning hours. Winter work is possible with tighter weather planning. We set the schedule by the forecast and the building, not by the calendar.
Will a replacement need a permit?
A commercial replacement is normally permitted work. Which code edition applies turns on the date the application is filed. Pasadena's permit center lists the 2025 California codes, including the Building Code and the Existing Building Code, as enforced for applications on or after January 1, 2026. We work through the application with you and confirm any local amendments with the city.
