What Condition Was the Roof In Before We Started?
The existing roof surface had reached the end of its serviceable life. Large sections of the modified bitumen membrane had delaminated and pulled away from the substrate, exposing bare wood decking across several areas of the field. The dark oxidized surface showed no meaningful solar reflectance, and standing water stains around multiple HVAC equipment curbs confirmed that water had been finding its way into the assembly.
The building at 2369 E 51st St in Vernon sits in an industrial corridor where rooftop equipment loads are high — this roof carried at least 4 separate packaged HVAC units. Every curb penetration is a potential leak point, and by the time our crew got on this roof, several of those transitions had failed. Flashing mastic had cracked, the membrane edges were lifting, and the underlying wood decking was visibly darkened with moisture damage in at least 3 distinct zones.
Project Gallery
Replacing the entire roof down to the deck was one option, but an overlay was viable here because the decking, once dried, retained structural integrity. A torch down overlay adds a fully adhered waterproof membrane directly over the prepared substrate, sealing everything — deck, curbs, parapet base, and field — in a single continuous system.
How Does a Torch Down Overlay Actually Work?
A torch down modified bitumen overlay uses an open-flame propane torch to heat-weld a reinforced asphalt membrane directly to the roof surface, creating a seamless, fully adhered waterproof layer without mechanical fasteners or adhesive cold-process gaps. The membrane itself is a polyester or fiberglass-reinforced bitumen sheet, typically 160 to 180 mils thick, which is far heavier than standard cap sheet applied with cold adhesive.
On this Vernon project, the installation sequence followed the standard low-slope protocol:
- Substrate prep: Loose or delaminated membrane sections were stripped, fastened down, or cut back to sound material. The deck was allowed to dry before torching began.
- Base sheet application: A base ply was torch-applied across the field, lapped and sealed at all seams with a minimum 3-inch overlap.
- Curb and parapet flashing: Each HVAC curb received a full membrane wrap — up the vertical face and over the top cap — before the field membrane tied in. Parapet walls were flashed to the top rail.
- Cap sheet: A granulated white cap sheet was applied as the final ply, providing both UV protection and the solar-reflective finish required under California’s Title 24 building energy standards.
White cap sheet on a commercial flat roof in the Los Angeles basin isn’t just cosmetic. California Energy Commission data shows that cool roof coatings on low-slope commercial roofs can reduce peak cooling loads by 10–15%, a meaningful number for a building running 4 or more rooftop packaged units through a Southern California summer. According to NOAA, the Los Angeles basin regularly records summer ambient temperatures above 95°F, conditions that accelerate dark-surface membrane degradation.
Our crews have observed that dark oxidized cap sheets on Vernon-area roofs tend to show surface cracking and granule loss within 8–10 years of installation — the combination of intense UV exposure and industrial heat loading shortens the cycle compared to coastal ZIP codes.
What Did the Finished Roof Look Like?
The completed surface is uniformly white, flat, and fully adhered across the field, with clean flashing transitions at all 4 parapet walls and each HVAC curb — exactly what a functioning low-slope membrane system should look like. The parapet cap flashing was reset and sealed, and the roof drains were cleared and integrated into the new membrane.
As of 2026, California’s Title 24 energy code requires low-slope commercial roofs in Climate Zone 9 — which includes Vernon — to meet a minimum aged solar reflectance of 0.55. The white granulated cap sheet installed here meets that threshold. Roof Replacement CA is Licensed by the California Contractors State License Board (CSLB), and this installation was performed to current code.
The building owner’s goal going into this project was simple: stop the leaks, pass a roof inspection, and avoid a full tear-off that would have added 2–3 days of labor and roughly 40–60% more in disposal costs. The torch down overlay achieved all three.
Ready to Assess Your Commercial Flat Roof?
If your flat roof is showing delaminated membrane, active leaks around HVAC curbs, or a surface that’s gone gray and brittle, a torch down overlay may extend the roof’s service life by 15–20 years at significantly lower cost than full replacement. Call Roof Replacement CA to schedule a roof evaluation at your Vernon-area commercial property.
