Metal roofing
Architectural shingles
Tile roofing
GAF
Owens Corning
Flat & low-slopeFree roof inspection with deck photos before we talk money - GAF and Owens Corning certified installation
Fast, Reliable Roof Installation Across Westmont
Roof installation in Westmont runs between $9,800 and $24,000 for most homes, with flat and low-slope systems landing on the higher end because they demand specialized torch-down or TPO membranes rather than standard shingles. Our Roofing Company - Westmont team has been installing roofs across this area for years, and we know exactly what these mid-century ranch homes throw at a roofing crew: UV-baked plywood, corroded flashing, and transitions that leak if they’re not re-flashed properly. Call (424) 435-5428 and we’ll send someone out to scope your roof and put a written price in your hand before any work starts.
Westmont’s housing stock is mostly 1940s and 1950s single-family ranches with flat or gently sloped roofs. That changes everything about how a roof gets installed here. A crew that only does pitched shingle work will miss what’s actually happening at your flashing and membrane transitions. We won’t.
Why Mercer Roofing Co Torrance Is Westmont’s Preferred Roof Installation Company
Westmont homeowners keep calling us back because we show up the way people here want to be treated. Every technician who comes to your door is background-checked, identity-verified, and uniformed under the Threshold Verified standard. Before we arrive, we send the technician’s name and photo to your phone. When they knock, they badge in with a photo ID. You know exactly who is on your property before you open the door. That matters in a neighborhood where people are home alone with young kids, or older and cautious about strangers.
Grant Whitlock leads our crew, and he’s set one rule above everything: a written price before a single nail goes in. Not an estimate. Not a ballpark. A line-item written price for the full roof installation scope. If anything changes on the job, you see it in writing first. That’s the only way we work, and it’s why Westmont customers across the 90047 and 90262 ZIP codes tell their neighbors about us.
We’re part of the Threshold Group family, founded in 2000. Each location is independently owned and operated, but every one of us is held to the same standard: background-checked, photo-badged, uniformed technicians on every visit. For Westmont that means the same professionalism whether we’re quoting a full tear-off near the 110 Freeway or doing a TPO replacement on a quiet cul-de-sac off Vermont Avenue.
Styles & brands we work with






Roof Installation Team Serving Westmont
Our Roof Installation crew works with shingle brands like GAF, CertainTeed, and Owens Corning, plus TPO and torch-down systems for the flat roofs that define Westmont. We do not send a generic crew and hope for the best. We send installers who have re-flashed low-slope transitions on Westmont ranch homes dozens of times and know what this city’s sun does to plywood decking over forty years.
Roof Flashing Installation in Westmont
Roof flashing installation in Westmont typically runs $1,400 to $3,800 depending on how many penetrations your roof has and whether we need to cut back stucco or siding to reach the old drip edge. Flashing is the metal that seals the places where your roof meets a chimney, a vent pipe, a wall, or a low-slope transition, and on Westmont’s flat and low-slope roofs it’s the part that fails first. UV exposure bakes the old flashing until it cracks or corrodes, and once that happens water gets behind it and into your decking.
Low-Slope Transition Flashing
On Westmont ranch homes we regularly replace transition flashing where a low-slope section meets a slightly steeper plane. The old metal was often nailed directly to the decking with no waterproofing membrane behind it, and after seventy years of sun and rain it leaks. We cut back the old material, install new drip edge, and lap fresh flashing over an ice and water shield so the seam stays dry.
Counterflashing and Stucco Work
Ranch homes in the 1940s and 1950s built with stucco exterior walls often have counterflashing embedded in the stucco itself. When that flashing corrodes, the only honest fix is grinding a clean line in the stucco, setting new counterflashing, and sealing it. That’s local Westmont work. A roofer who’s never cut into the stucco on a mid-century rancher will patch the leak and leave the root cause in place.
TPO Roofing Installation in Westmont
TPO roofing installation in Westmont typically runs $11,500 to $22,000 for a full single-story ranch home, including the tear-off of the old system and new insulation and membrane. TPO is a white, heat-welded single-ply membrane that reflects UV instead of absorbing it. On Westmont’s intense south-facing roof slopes that reflectivity adds real years to the roof’s life, and it keeps the attic cooler during the hottest stretches of July and August.
Full Tear-Off and TPO Membrane
A proper TPO install begins with getting down to the decking. On Westmont homes that’s usually plywood or spaced board sheathing from the original build, and we always expect to find at least a few sheets that were UV-damaged or rotted from old leaks. We replace those before the new insulation goes down, because no membrane in the world fixes a bad deck.
TPO on Flat and Low-Slope Sections
Flat roofs in Westmont hold water in a way pitched roofs never do. TPO solves that with heat-welded seams, which means there’s no glue or tape to peel back when ponding water sits after a winter storm. We also slope the new insulation where the structure allows so water drains instead of pooling. On the low-slope transitions we run TPO up under the flashing, not just to it, which is the detail that keeps the first heavy rain from finding its way inside.
Trusted Brands We Service in Westmont
We install and repair systems from IKO, Atlas, and Boral, along with the full GAF and CertainTeed lines for shingle work. For Westmont we keep materials and common flashing profiles stocked locally, which means faster turnaround when your old roof has to be torn off and replaced during a dry window between winter storms. We do not push a single brand on every house. We match the system to what your roof actually needs, whether that’s Atlas shingles on a pitched section or an IKO membrane on a flat addition.
See the difference
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After
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After
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AfterCommon Roof Installation Problems We See in Westmont Homes
- UV-cracked composition shingles on south-facing slopes. The sun here is relentless, and shingles that face due south fail years earlier than the rest of the roof. We see the pattern constantly on homes along Normandie Avenue and Vermont Avenue: the south plane is cracked and curled while the north plane still looks serviceable.
- Wind-driven debris from the railroad corridor. Homes on the east side of Westmont, closer to the tracks, catch torn starter strips and lifted underlayment after windy days. The debris isn’t just cosmetic – once the starter strip is loose, the first real windstorm peels back whole sections of shingle.
- Ponding water on low-slope roofs after winter rain. Original 1940s and 1950s roof decks in Westmont rarely have drainage slopes that meet modern standards. After a heavy rain, water sits in low spots and eats through the membrane. A new roof has to fix the drainage, not just recover it.
- Corroded flashing around chimneys and vents. Decades of dry heat followed by soaking rains turn old galvanized flashing into rust. We routinely find flashing on Westmont ranches so far gone it crumbles when we touch it, which means the leak has been active longer than the homeowner realized.
Pricing for Roof Installation in Westmont, CA
A complete roof installation on a typical Westmont ranch home runs $9,800 to $24,000. The spread comes down to three things: whether your roof is pitched shingle (lower end) or flat/low-slope TPO or torch-down (higher end), how much decking repairs add once we open up what’s underneath, and how many flashing transitions your house has. County permitting for Westmont roof work adds roughly $200 to $500 depending on project valuation. We include the permit line in your written quote, and we pull the permits ourselves. You get item-by-item pricing before work starts, no change orders dropped on you mid-job. Call (424) 435-5428 to schedule a free estimate.
We Also Serve Cities Near Westmont
Beyond Roof Installation in Westmont, our crews serve Torrance, Inglewood, Carson, and Hawthorne. Same written-price-first standard, same Threshold Verified technicians, same 365-Day Done Right Promise on every job. If you’re just outside Westmont and wondering whether we’ll come to you, call and ask – we’ll be straight with you about scheduling.
Serving Westmont, CA - Our Local Coverage Area
We’re based in the Westmont area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs About Roof Installation in Westmont
Flat and low-slope roofs cost more because they require specialized membrane systems like TPO or torch-down, heat-welded seams, and more careful flashing work at every transition. Westmont’s ranch homes have these roofs on most of their square footage, which means you’re paying for a watertight membrane rather than overlapping shingles. Call (424) 435-5428 and we’ll give you an exact quote for your home’s roof type – the estimate is free.
Homes west of Vermont Avenue, closer to the 110, absorb more direct UV on south-facing slopes, which accelerates shingle cracking and flashing corrosion. We account for that by inspecting the south slope first and recommending UV-resistant materials where exposure is worst. Call (424) 435-5428 and we’ll walk your roof with you and point out what the sun has already done.
Yes, a full roof installation in Westmont requires permits through Los Angeles County. We pull them for you and include the permit fees in your written quote. You never have to file paperwork or chase an inspector – we handle both and pass inspection before we consider the job done.
Ice and water shield is a self-adhesive waterproofing membrane installed on decking in vulnerable areas like valleys, eaves, and low-slope transitions. In Westmont you don’t need it for ice, but you absolutely need it for wind-driven rain and the ponding water that sits on flat sections. We include it on every slope transition and around every penetration. Call (424) 435-5428 for a quote that includes it line by line.
We start by inspecting the starter strips along the eaves and rakes, since those are the first thing sustained wind loosens. We also check for lifted underlayment at the corners of the roof. For homes east of Vermont Avenue near the tracks, we recommend upgraded nailing patterns and reinforced starter strips as part of the install. Call (424) 435-5428 and we’ll assess your exposure and give you a written recommendation.
Written by Grant Whitlock, Owner at Mercer Roofing Co Torrance, serving Westmont since 2000.