Commercial roofing · Reroofing
Commercial reroofing and roof replacement
Sometimes the roof is finished and the right answer is a new one. This page covers when code forces a tear-off, what the 2025 Energy Code adds to a replacement that owners rarely budget for, how the membrane gets chosen, and how the work is run on a building that has to stay open.
- CA Licence #1052777
- We price match like-for-like bids
- 5–10 years on labor and workmanship
What a properly run replacement gets you
Why the details matter on a commercial tear-off
Test-cut evidence, not a guess
Layer count, deck condition, and insulation state confirmed before the scope is written - not assumed from the parking lot.
Code compliance built in
Cool roof reflectance and Table 141.0-C insulation handled as part of the scope, not discovered at inspection.
The building stays open
Phased tear-off sequenced around dock doors, tenant hours, and production - only opening what can be dried in the same day.
A documented closeout
Manufacturer product data, CRRC listing, Title 24 certificates, warranty, and closeout photos - the full record, not just an invoice.
First: make sure you actually need one
We are a certified coating applicator, so read this with that in mind and then check it against your own roof. A great many low-slope roofs that get replaced in this market did not need to be. If the deck is sound, the insulation is dry, the membrane is still adhered, and the roof drains, you are looking at a spent weathering surface on an otherwise intact assembly — and replacing the whole thing means paying to landfill components that were still working.
The tests that settle it are a moisture survey, adhesion testing on the actual substrate, and test cuts. We lay the whole decision out onroof coating vs. replacement, including every condition where the answer is genuinely a tear-off.
When it is a tear-off, we will say so and price it. What follows is what that job involves.
Code
When the code requires removal down to the deck
A recover — new roofing installed over the existing covering — is not always available. Section 1511 of the building code as adopted in California prohibits a roof recover under any of these conditions:
- The existing roof or covering is water soaked, or deteriorated enough that it is not an adequate base for additional roofing.
- The existing covering is slate, clay, cement, or asbestos-cement tile.
- The roof already carries two or more applications of any type of roof covering.
The third one catches more buildings than owners expect, and it is why the layer count matters so much. If a previous owner recovered the roof instead of replacing it, the next roofing event is a mandatory tear-off — the most expensive and most disruptive option on the table, with no way to opt out.
The exception worth knowing: a protective roof coating is treated in the code as maintenance or repair rather than as a new covering layer. Beginning with the 2018 code cycle the model codes state directly that a new protective coating over an existing coating or covering is permitted without tear-off and need not be counted as an additional roofing layer. On a two-layer roof, that is often the only path that is not a tear-off.
Asbestos changes everything. Older built-up roofs, mastics, and asbestos-cement products in Los Angeles County housing and industrial stock require survey, notification, and licensed abatement before removal. Scope it early — discovering it mid-tear-off is the worst possible time.
Energy code
What Title 24 adds to a replacement
Cool roof reflectance
Altering the lesser of 50 percent of the roof area or 2,000 square feet triggers the nonresidential cool roof requirement. For low-slope roofs the prescriptive threshold is a minimum aged solar reflectance of 0.63 with thermal emittance of 0.75, or an SRI of 75. For steep-slope nonresidential roofs it is aged reflectance of 0.20 with emittance of 0.75, or an SRI of 16. Compliance is documented against the CRRC-rated aged values for the exact product and color installed.
Insulation
Section 141.0(b)2 also requires the altered area of a low-slope roof replacement or recover to be insulated to the level in Table 141.0-C for your climate zone. Exceptions exist — including recovers that add new above-deck insulation, roofs already insulated above a threshold, tapered insulation at drains, and cases where equipment constrains the buildup — and they are worth working through carefully, because they change the job.
What that means physically
Insulation raises the roof. On a building whose curbs, thresholds, parapets, drains, and scuppers were all detailed around the old elevation, a couple of inches is not a small change. Base flashing height at rooftop unit curbs is the usual pinch point, followed by door and hatch thresholds and drain sumps. Expect a mechanical trade in the scope.
Compliance documents
- CRRC Product ID for the exact product and color
- Aged SR, TE, and SRI as listed by CRRC
- Certificate of Compliance (NRCC-ENV) at permit application
- Certificate of Installation (NRCI-ENV) signed after the work
- Manufacturer product data for the submittal record
The 2025 standards apply to permits applied for on or after January 1, 2026. Climate zone, applicable exceptions, and local amendments have to be confirmed for your specific address and jurisdiction — Los Angeles County has a lot of building departments in it. We pull the values for the address rather than quoting from memory.
Selection
Choosing the system
There is no best commercial roof. There is a right one for your deck, your exhaust, your traffic, your wind exposure, and how long you intend to hold the building.
TPO
The default single-ply on new low-slope commercial work: white, heat-welded seams, good chemical resistance, and a strong cool-roof profile straight out of the box. Mechanically attached, induction welded, or fully adhered depending on the wind design and the deck. The thing to specify carefully is membrane thickness and the reinforcement scrim, because thin membrane is where TPO earns its bad stories.
PVC
Heat-welded like TPO, with better resistance to grease, oils, and chemical exhaust. That makes it the right call over restaurants, food processing, and any building venting fats or solvents onto the roof — which covers a meaningful share of the industrial buildings along the 60 corridor and most of Kern County agricultural processing.
Modified bitumen
Torch, cold-adhesive, or self-adhered multi-ply asphaltic. Tough, redundant, forgiving of foot traffic, and still the sensible answer on small complex roofs with many penetrations, and on roofs that will take abuse. Cap sheet selection drives the reflectance, so the cool roof requirement has to be designed in rather than assumed.
Built-up roofing
The traditional multi-ply asphalt and felt system, usually with a surfacing. Rarely the value choice on new work today, but relevant because so much of the existing low-slope stock in Los Angeles County is BUR, and knowing what is on the deck determines both the recover options and the coating options.
Sprayed polyurethane foam
The one system that adds both insulation and slope, sprayed in place and then coated. It solves the two problems a coating alone cannot, which makes it the answer on a roof with a genuine drainage defect and inadequate insulation. It also requires a substrate and a crew that suit it, and the coating over it is what protects it — foam has no UV resistance at all.
Standing seam and metal retrofit
On existing screw-down metal, the choice is usually between a retrofit standing seam system over subframing and a coating restoration of the existing panels. The retrofit is a real roof replacement with a long life; the restoration is a fraction of the cost and stops the fastener and seam leaks. Which one is right depends on panel condition and how long you intend to hold the building.
What actually drives the specification
The deck
Steel, concrete, wood, or lightweight insulating concrete — each one constrains attachment, fire assembly, and thermal barrier requirements differently. Steel deck governs fastener selection and pullout; concrete may require adhesive attachment; lightweight insulating concrete needs specific fasteners and a pull test to confirm they hold. This is settled by test cuts and pull testing, not by assumption.
Wind
Attachment density is an engineering output: wind loads for your site and building geometry, with heavier fastening at corners and perimeters where uplift concentrates. Low-slope roof edge securement is required by the building code to comply with ANSI/SPRI ES-1. Edge metal is where a large share of wind failures actually begin, and it is a favorite place for a low bidder to save money.
What is coming off the roof
Kitchen exhaust, food and agricultural processing, solvents, and heavy equipment oil all attack membranes differently. PVC handles grease and chemical exposure that will shorten a TPO roof. If your building vents anything, that belongs in the specification conversation on day one.
Traffic
A roof with a dozen packaged units and a monthly service contractor needs a durable membrane and real designated walkways. A roof nobody visits does not. Walkway systems are cheap relative to the membrane they protect and they are the first thing cut from a bid.
Hold period
A building you intend to sell in three years and a building your family trust will own in twenty are different engineering problems with different right answers. Tell us which one this is. It changes what we recommend.
Execution
Running a reroof on a building that stays open
Most of our commercial work is on buildings that cannot close — distribution centers along the 60 corridor through Commerce and City of Industry, multi-tenant retail, manufacturing, and agricultural processing in Kern County during a season that does not pause. The planning that matters:
- Only open what you can dry in. Tear-off is sequenced so that every square of deck opened in a day is watertight before the crew leaves. This is the single discipline that separates a professional reroof from a disaster.
- Sequence around operations. Dock doors, production lines, tenant hours, and truck routing. Staging and dumpster placement are planned around your parking field, not the other way around.
- Protect what is below. Dust and debris control over occupied space, food handling areas, and clean processes. In a packing house or a food plant this is a food-safety issue, not a courtesy.
- Coordinate the other trades. Mechanical work at raised curbs, electrical at conduit supports, and solar de-installation if there is an array. These are scheduled up front, because discovering them in week two stops the job.
- Weather windows are real here. The dry season is the season, and the fall queue fills. Planning a spring or summer start is how you avoid being on a waiting list in December.
If your roof is a restoration candidate, none of the above applies at all — no tear-off means no open deck, no debris, and no closure. That is the honest reason to evaluatecoating versus replacementbefore committing to a tear-off.
What we need to bid it
- Roof area, and a roof plan or drainage plan if one exists
- Existing membrane type, approximate age, and any known layer count
- Deck type, if known
- Leak history — where, how often, and what has been patched
- Rooftop equipment inventory, and whether there is solar
- Existing warranty and who issued it
- Occupancy, tenant hours, and any operational blackout dates
- Whether the building is held long term or headed for sale
What comes back is a written scope: the tear-off or recover determination and why, the assembly with insulation and attachment, the code compliance path and documentation set, the edge and detail work, the warranty terms, and a schedule built around your operations. If a licensed contractor has already bid the same scope, we will match it.
Why call Green Coast
Credentials that matter on a replacement
- Two CSLB classifications - C-39 (Roofing) and B (General Building), in business since 2019. Curb rework, structural questions, and multi-trade coordination stay in-house.
- We price match like-for-like bids from another licensed contractor.
- 5–10 years on labor and workmanship, on top of the manufacturer warranty on the system.
- California license #1052777 - licensed, bonded, and insured. Verify it at cslb.ca.gov.
What you end up with
A new assembly matched to your deck, exhaust, traffic, and wind exposure, with the tear-off-or-recover determination backed by test cuts, the Title 24 compliance documentation filed, and a schedule built around your operations rather than ours.
Where we work
Commercial reroofing across Los Angeles County and Kern County, plus Orange, San Bernardino, and Riverside counties. See the full service area.
Questions owners ask
How do I know whether I have to tear off or can recover?
It is determined by what is actually on the deck, which is determined by test cuts. Section 1511 of the building code as adopted in California prohibits a recover where the existing roof is water soaked or deteriorated past being an adequate base, where the existing covering is slate, clay, cement, or asbestos-cement tile, or where the roof already carries two or more applications of any type of covering. Owners frequently do not know their layer count, and the answer changes the project by a large multiple. Permit interpretation is local, so it gets confirmed with your building department during scoping.
Why does replacement cost so much more than the membrane price suggests?
Because the membrane is a modest share of it. A low-slope replacement carries tear-off and disposal, insulation brought up to current Energy Code for your climate zone, a roof plane that is now higher than it was, and then everything that has to be reworked around that new elevation — rooftop unit curbs that no longer give you flashing height, door and hatch thresholds, parapet and edge metal, drain sumps, scupper elevations, and conduit and gas line supports. On an occupied building with a dense equipment field, that rework is frequently the largest single line and it never shows up in a per-square-foot comparison.
Does a replacement trigger Title 24?
Yes, on both counts. Altering more than 50 percent of the roof area or more than 2,000 square feet, whichever is less, triggers the nonresidential cool roof requirement — for low-slope roofs, a minimum aged solar reflectance of 0.63 with thermal emittance of 0.75, or an SRI of 75, documented against a CRRC-rated product. A replacement or recover additionally has to insulate the altered area to the level in Table 141.0-C for your climate zone, with exceptions including recovers that add new above-deck insulation. A recoat, by contrast, is not required to be insulated. The 2025 standards apply to permits applied for on or after January 1, 2026.
Can you reroof without shutting the building down?
Usually, with planning. A tear-off is sequenced so that only as much deck is opened as can be dried in the same day, with the work phased around dock doors, production areas, and tenant spaces. But be honest with yourself about it: there is a period where the building is exposed, there is debris and crane and dumpster traffic in your parking field, and there is noise directly over occupied space. That disruption is precisely why restoration is worth evaluating first when the roof qualifies for it.
What about wind uplift and edge securement?
They are engineering requirements, not preferences. Attachment is designed for the wind loads at your site and building geometry, with denser fastening at corners and perimeters where uplift concentrates, and low-slope roof edge securement is required by the building code to comply with the ANSI/SPRI ES-1 standard. Edge metal is where a large share of wind failures start, and it is also the line item most often value-engineered by a bidder who is trying to be low. Ask what edge system is being proposed and to what standard.
What documentation comes with the job?
Manufacturer product data and system approval, the CRRC listing for the exact product and color, the Title 24 compliance paperwork — the Certificate of Compliance filed at permit application and the Certificate of Installation signed after the work — the manufacturer warranty, our workmanship warranty, and closeout photos. Ask every bidder for that list. The ones who cannot produce it are the ones who were cheapest for a reason.
Request a roof evaluation
We will walk the roof, cut it where it needs cutting, tell you what is actually on the deck, and give you a written answer on whether this is a replacement or a restoration — with the code path and the documentation for either one.
Green Coast Builders · CA License #1052777 · Serving Los Angeles, Commerce, City of Industry, Anaheim, San Bernardino, Riverside, Bakersfield, and Ridgecrest.