Free roof inspection with deck photos before we talk money - GAF and Owens Corning certified installation
Before
After
Before
After
Before
AfterFast, Reliable Roof Installation Across San Marcos
A new roof in San Marcos typically runs $9,500 to $18,000 for a standard composition shingle home, while concrete tile tear-offs and Class A fire-rated assemblies in the hillside tracts usually land between $18,000 and $34,000. Those are real numbers we’ve quoted on homes from San Elijo Hills to the older pockets off Grand Avenue, and they reflect what this city’s specific housing stock and fire-zone code requirements actually demand. If you’re weighing a roof installation, call (743) 200-8347 and we’ll give you a written line-item price before any work gets scheduled.
We know San Marcos roofs because we work on them constantly. The concrete tile wave built between the late 1990s and mid-2000s is now hitting the 20-to-25-year mark, and that’s where we spend most of our days. Our Roof Installation crews are familiar with the tracts along Twin Oaks Valley Road and the master-planned sections of San Elijo Hills, which means we arrive knowing what’s likely under the tiles before we even set up the ladder. Grant Whitlock, who leads Mercer Roofing, insists every estimator who quotes a San Marcos job understands the inland thermal band and what it does to underlayment a decade before any tile shows damage.
Why Mercer Roofing Is San Marcos’s Preferred Roof Installation Company
Two things set us apart in San Marcos, and they both come down to how we treat the person answering the door. First, every technician who arrives gets his name and photo sent to you before the visit, and he badges in with a photo ID at the door. If you’re home alone with young kids, or you’re older and want proof of who’s on your property, that specific detail matters more than any brochure claim. It’s the Threshold Verified standard, and every Mercer location, including the crews serving San Marcos from our San Diego dispatch office, is contractually held to it.
Second, we put every price in writing before work starts, and we don’t change it unless you approve a change in writing first. No verbal estimates, no “we’ll see how it goes.” Every roof installation in San Marcos starts with a written line-item quote. Every repair carries a written guarantee, and if a repair fails within 365 days, we make it right or come back free, part of our 365-Day Done Right Promise. That guarantee is included with every job, not sold as an add-on.
We also stock shingle inventory from GAF, CertainTeed, and Owens Corning locally, which means San Marcos customers aren’t waiting on a warehouse shipment from another county when a project is already underway. Call (743) 200-8347 and a live person answers, any hour, any day. Not a voicemail tree, not a callback form. You’ll speak to a human who can schedule a roof installation estimate on the spot.
Roof Flashing Installation in San Marcos
Roof Flashing Installation in San Marcos usually runs $450 to $1,600 depending on how many penetrations, valleys, or chimneys need new metal, and it’s one of the most overlooked pieces of a watertight assembly. Flashing is the metal that carries water off the places where your roof changes direction or gets interrupted, vents, chimneys, skylights, valleys, and wall intersections. When flashing fails, water gets behind the tile or shingle and finds the decking, and by then the damage is already done. On older San Elijo Hills homes, we routinely replace corroded galvanized flashing at the same time we address failed underlayment, because doing one without the other just means a second leak in a year.
Valley and penetration flashing
Valleys are where two roof planes meet, and they move more water than any other part of the roof. In San Marcos, Santa Ana wind drives rain sideways, which means valley flashing that isn’t properly lapped or is too narrow gets overrun fast. We use wider, heavier-gauge valley metal and mechanically fasten the edges so wind-driven water can’t get underneath.
Chimney and skylight flashing
Chimney flashing on stucco-and-tile San Marcos homes from the 1990s and early 2000s often used thin step flashing that has since pulled away from the mortar. Skylights are just as bad: the original curb flashing degrades under inland UV exposure far faster than it does at the coast. We pull the old metal, inspect the surrounding sheathing, and set new flashing with a proper reglet cut into the stucco where needed.
TPO Roofing Installation in San Marcos
TPO Roofing Installation in San Marcos typically costs $7 to $11 per square foot installed for low-slope or flat-roof portions of a home, though most single-family houses here don’t need it. Where we do install TPO is on flat-roof additions, patio covers, and some mid-century homes along Grand Avenue and the older downtown pockets that have low-slope sections. TPO is a thermoplastic membrane, heat-welded at the seams, and it handles the inland sun better than old modified bitumen or built-up roofs that bake and crack under the same UV load we’ve been talking about.
When TPO makes sense
If your San Marcos home has a flat or very low-slope roof section, tile and composition shingles aren’t the right material for that surface. TPO is. It’s white, so it reflects heat instead of absorbing it, which matters when your attic is already fighting a 95-degree inland afternoon. We install it over new or recovered insulation, and the heat-welded seams stay flexible through thermal cycling.
Replacing old flat-roof material
Many of the flat sections we tear off in older San Marcos homes are original built-up roofs from the 1960s and 1970s, full of blisters and alligator cracking. We strip it to the deck, inspect for rotted plywood, replace any compromised sheathing, and then install the TPO membrane with a fully adhered system. The seams are hot-air welded, not glued, which is the difference between a roof that lasts 20 years and one that peels in six.
Trusted Brands We Service in San Marcos
We install and repair shingle roofs using GAF, CertainTeed, and Owens Corning systems, and we stock the most common colors and lines for San Marcos customers so tear-off and replacement moves without supply delays. Every brand we carry offers a Class A fire rating when installed as part of a full assembly, which is the baseline requirement in the hillside fire hazard zones. If you’re comparing bids from two San Marcos roofers, ask which specific shingle they’re quoting, because a GAF Timberline and a builder-grade CertainTeed are not the same roof, and the difference in longevity shows up fast in this inland climate. We’re manufacturer-recognized across these lines, and Grant Whitlock’s crews are trained on each brand’s installation requirements, which is what keeps the manufacturer warranty valid.
Common Roof Installation Problems We See in San Marcos Homes
- Failed hot-mopped underlayment under intact tile. San Elijo Hills and the tracts above Twin Oaks Valley Road were built with hot-mopped felt underlayment beneath concrete tile. At the 20-to-25-year point, that felt dries, cracks, and loses waterproofing capacity, while the tiles above still look fine. Homeowners find out when water stains appear on the ceiling and no broken tile can be found.
- California fire-zone code triggers mid-project. Most hillside San Marcos tracts fall inside Cal Fire Very High Fire Hazard Severity Zones. Pull a permit for a roof installation and the scope legally changes: Class A assembly, ice and water shield in valleys, and flashing upgrades that weren’t in the original bid. If a contractor didn’t price those in from the start, the change order lands mid-job.
- Tile cracking and lifting from Santa Ana wind and inland heat. San Marcos sits inland enough that thermal cycling is more aggressive than in Carlsbad or Oceanside at the same latitude. Tiles crack along ridgelines and lift in valleys, then wind drives rain sideways under the field, bypassing whatever underlayment is left.
- Decking rot at penetrations and eaves. By the time flashing fails on a chimney, vent, or skylight, water has usually been getting behind it for a year or more. We open these areas on older San Marcos homes and commonly find rotted plywood or OSB that needs replacement before the new roof can go down correctly.
Pricing for Roof Installation in San Marcos, CA
Here are straight numbers from jobs we’ve quoted across San Marcos. A full composition shingle roof installation on a standard 1,800 to 2,400 square foot home runs $9,500 to $18,000. Concrete tile tear-off and replacement, including a Class A assembly, runs $18,000 to $34,000 depending on the roof’s complexity, pitch, and tile condition. Roof Flashing Installation alone is $450 to $1,600. TPO flat-roof sections run $7 to $11 per square foot. The biggest cost drivers are whether the roof needs a Class A fire-rated assembly, whether decking has to be replaced, and how much flashing needs rebuilding. Every estimate is free, written, and line-itemed. Call (743) 200-8347 and you’ll get a real price, not a range someone made up over the phone.
We Also Serve Cities Near San Marcos
Beyond San Marcos, our roof installation crews cover Roof Installation in San Marcos and the surrounding North County cities: Vista, Escondido, Carlsbad, and Encinitas. If you’re in any of these areas and need a written roof estimate, the same Threshold Verified standard applies: name and photo before arrival, photo ID badge at the door, and a written price before any work begins.
Serving San Marcos, CA - Our Local Coverage Area
We’re based in the San Marcos 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 San Marcos
Because the leak isn’t coming from the tile. It’s coming from the underlayment beneath it. On the concrete tile homes built in San Elijo Hills and along Twin Oaks Valley Road from the late 1990s through the mid-2000s, the original hot-mopped felt underlayment has now aged 20 to 25 years. In San Marcos’s inland heat, that felt dries out, cracks, and stops shedding water, while the tiles above still look completely intact from the ground. We confirm this with a water test: the roof fails before a single tile shows damage. The fix is a full tear-off and new underlayment, not a tile swap. Call (743) 200-8347 and we’ll inspect yours and show you exactly what’s happening underneath.
Yes, and it changes it in a way most homeowners don’t see coming. If your San Marcos home sits in the hillside tracts, which includes most of San Elijo Hills and the areas above Twin Oaks Valley Road, you’re likely in a Cal Fire Very High Fire Hazard Severity Zone. That means any permitted re-roof must meet Class A assembly requirements, which means specific underlayment, specific flashing details, and in some cases specific tile or shingle choices. A contractor who quotes you a standard Class B or unrated assembly either doesn’t know the local code or is planning to pull the permit and hit you with a change order when the inspector flags it. We price the Class A assembly into the initial written bid so there’s no mid-job surprise.
Failed waterproofing, rotted decking at penetrations and eaves, and code upgrades that the permit triggers. On a recent concrete tile tear-off in San Elijo Hills, our crew found the original hot-mopped underlayment dried, cracked, and completely unwaterproofed beneath tiles that still passed a walk-over inspection, and the roof failed a water test before showing a single broken tile. We stripped to the decking, replaced cracked tile battens, laid new ice and water shield in the valleys and along all penetrations, set a Class A-rated assembly to satisfy the Very High Fire Hazard Severity Zone requirement, and installed new drip edge at the fascia before the tiles went back down. That’s what a real roof installation in San Marcos looks like, and it’s why our estimates include inspection of what’s underneath before we finalize a price.
Yes. San Marcos sits 10 to 15 miles inland, behind the marine layer that moderates Carlsbad and Oceanside. That means hotter summer surface temperatures and more aggressive thermal cycling. Tile and shingle expand and contract more each day, which accelerates UV breakdown of underlayment and causes tiles to crack or lift along ridgelines and in valleys. Santa Ana wind events add another layer: wind drives rain sideways under the field, bypassing flashing and underlayment that has already degraded. A roof in San Marcos simply ages faster than the same roof at the coast, and the materials and installation details have to account for that. We quote for the inland reality, not the coastal one.
Put them side by side and check five things: the specific shingle or tile brand and line, not just “composition shingle”; whether underlayment is included and what type; whether the bid includes a Class A assembly if your home is in a fire hazard zone; whether decking replacement is included or will be added as a change order; and whether flashing replacement at penetrations is priced in. Two bids that both say “$15,000” can be wildly different roofs. Ours is a written line-item price, and every line is spelled out before work starts. If you’re comparing quotes, call (743) 200-8347 and we’ll walk through exactly what’s in ours, and what to look for in the other one.
When you’re ready to get a real number for your San Marcos roof, call (743) 200-8347. A live person answers, and we’ll schedule a free written estimate. You’ll know who’s coming before they arrive, and you’ll have the price in writing before any work starts.
Written by Grant Whitlock, Owner at Mercer Roofing, serving San Marcos and the surrounding North County area since 2000.