Los Angeles County, California

Commercial Roof Replacement in Los Angeles

Replacing a low-slope commercial or apartment roof starts with one question: does the old membrane come off to the deck, or can a new one go over it? That decides the price. We count the layers and check the drainage on a free visit, and the scope comes in writing.

Tell us about your roof Call (310) 857-2520

Free roof inspection
We come out, get on the roof, and tell you what we find.
The price in writing
A written quote before anyone starts, with nothing to sign on the spot.
Licensed roofers
Our roofer who comes out holds a current California license.
Across Los Angeles County
From the Valley and the foothills to the Westside and the South Bay.

Replacing a low-slope commercial or multi-unit roof means stripping the old membrane down to the deck or covering it with a new one. Code decides which one you get. That decision changes the price and the schedule more than the choice of membrane.

A recover is ruled out where the roof is water soaked, too deteriorated to serve as a base, or already carrying two or more applications. LA County is tighter and lets one existing layer stay, and the rest comes off.

Flat and low-slope, typical range$12,000 to $30,000

That band covers a roof the size of a house. A commercial deck can sit well above it, and anything bigger gets walked and measured. Costs page.

A test cut is the only way to know what is under the membrane. Insulation this wet cannot be covered over, and it is what decides whether the job is a recover or a tear-off.

Count the layers first

Core cuts tell you two things a scan cannot: how many layers are on the deck, and whether the insulation under them is wet. A recover over wet insulation is not recommended, and a moisture scan should be confirmed with test cuts. On an LA County roof the layer count decides whether a recover is legal at all, so get it first. The building department inspects once the layers are off, or before new material goes down.

What Title 24 adds

The energy code is why so many low-slope roofs in this county are white. The difference against the parapet cap beside it is the reflectance the code is asking for.

All sixteen California climate zones ask nonresidential low-slope roofs for a three-year aged solar reflectance of 0.63 and thermal emittance of 0.75, or an SRI of 75. Aged means the value measured after three years of exposure. The number printed for a new sheet is a different figure. A membrane without a Cool Roof Rating Council rating defaults to 0.10, so it cannot meet 0.63.

The energy code pulls a re-roof in once more than 50 percent of the roof area or more than 2,000 square feet is altered, whichever is less. On a large roof one phase can cross that on its own, so measure the area you are altering before assuming the job falls outside it.

The roof gets thicker

Every inch of new insulation is an inch off the height of every curb, drain and door threshold on the roof. That is what has to be checked before the boards are ordered.

It also requires R-23ci on roof alterations in Climate Zones 1 to 5 and 9 to 16, and R-17ci in Zones 6 to 8. That board goes above the deck and under the membrane, so it is part of the roof assembly and gets priced with the roof instead of as a separate insulation job. Los Angeles straddles the line: coastal addresses in Zone 6, inland valleys in Zone 9, by ZIP code.

R-17 works out to about 2.5 inches of polyiso plus a half-inch coverboard, and R-23 to about 3.5 plus a half-inch. That is three to four inches of new build-up above the deck.

Flat and low-slope, typical range$12,000 to $30,000The inspection is free, and the price for your roof comes in writing.

Get a price for your roof

Drainage decides how long it lasts

On a replacement the code waives the quarter-inch-per-foot minimum slope where the roof provides positive drainage. The code's definitions chapter puts a number on it: the roof drains within 48 hours of precipitation, with deck deflection allowed for. Standing water is covered on the commercial roofing page. A replacement is the point where it gets corrected, and that correction has to be priced before the membrane is ordered.

LA County Public Works sizes roof drains on 3 inches of rain per hour, without help from overflows. The drain body, the leaders and the overflow piping are plumbing work. A roofer flashes the drain into the membrane and sets the sump around it. The piping below belongs to the plumber.

Curbs, units and license scope

Base flashing runs at least 8 inches up from the membrane, and new insulation eats that height. A recover may not be possible where 8 inches cannot be provided at through-wall details.

A roofing license covers the work that seals and waterproofs the structure. Lifting a rooftop HVAC unit is mechanical work, and where solar comes off, LA County requires an electrical or solar contractor to put it back, on a separate permit.

Ask which warranty is which

A manufacturer's no dollar limit guarantee and an installer's workmanship warranty are separate pieces of paper, and a bid may include one, both or neither. Ask which of the two is on the table before you compare prices. Johns Manville, as one example, issues NDL guarantees only through contractors it has designated. Ask each bidder on your building whether they hold that designation, and the manufacturer will confirm it.

JM excludes damage from improper drainage on every system except PVC and TPO, damage from foot traffic and stored material, and pre-existing materials left under a recover. On a flat deck read the drainage exclusion twice. The standing water the county sizing rules are written around is the same water the guarantee will not cover.

What to ask before you sign

How many layers are on the deck, and what did the core cuts show?
Which climate zone is this address in, and what R-value does that set?
Which warranty comes from the manufacturer, which from the installer, and how long does each run?

Get the layer count and the drainage plan in writing before anyone quotes. The visit is free, because the layer count and the drainage only show up on the roof. Our roofer who comes out holds a current California license and hands over the CSLB number.

The offer

$500 off a new roof, 10% off any repair

Send your request online from this page and the offer is attached, with nothing to remember.

We get on the roof, and into the attic if that is where the answer is
You get photographs of whatever we find
The price in writing, with nothing to sign on the spot

Claim it on a free inspection

Drainage firstA replacement is the point where ponding gets corrected, and it has to be priced before the membrane is ordered.
Everything on the roofUnits, curbs, drains and scuppers all get detailed around, and new insulation changes their heights.
Base flashing heightIt runs at least 8 inches up, and new build-up eats into that.