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CertainTeed Home Additions & ADU: The Los Angeles Owner’s Guide
If you’re planning a home addition or ADU in Los Angeles and want CertainTeed materials specified, expect to pay between $53,100 and $153,400 for a completed addition, and $106,200 to $259,600 for a full ADU build. That range includes framing, roofing, drywall, insulation, windows, and finish work using CertainTeed products where they matter most: siding, roofing, and insulation. Most owners reach out to us after their existing addition or ADU shows water intrusion at the roofline, failing insulation that drives up cooling bills, or siding that’s warped in the San Fernando Valley heat. We spec CertainTeed because it holds up in Los Angeles sun and occasional heavy rain, and we can match it to your existing structure without guesswork.
Here’s what to know before you spend a dollar: we’re an independent Los Angeles contractor, not a CertainTeed dealer or affiliate. We install and source CertainTeed products because they’re reliable and we can get them quickly. Isaac Pruett runs Mason Remodeling Co Los Angeles, and he’s spent two decades building additions and ADUs across LA County. We’ll walk you through every product choice, every line item, and every schedule milestone before work starts.
Which CertainTeed Models This Applies To
CertainTeed doesn’t make “home additions” as a product line. What it makes are the material systems that go into them: roofing shingles, vinyl and polymer siding, insulation, and drywall. The compatibility question is really about which CertainTeed product lines suit your addition or ADU, and how to match them to what’s already on your main house.
For roofing, the CertainTeed Landmark series is the most common we install on LA additions. Landmark Pro and Landmark Premium carry heavier weights and better wind ratings, which matters in canyon areas like Topanga or the hills above Studio City. For siding, CertainTeed’s Monogram vinyl and Cedar Impressions polymer shake are the two lines that hold up best in direct Los Angeles sun without fading or warping. For insulation, the CertainTeed InsulSafe SP blown-in fiberglass and SmartBatt kraft-faced batts are what we spec for ADU exterior walls and attic spaces.
Compatibility gotcha: if your main house was built with a discontinued CertainTeed siding profile, you won’t find an exact match. CertainTeed retires profiles every few years. We can match color within 90% using current lines, but a perfect match on a 20-year-old profile isn’t possible. We’ll show you samples before ordering.
On parts: OEM CertainTeed materials are worth the cost for roofing underlayment and siding, where warranty registration matters. For insulation and drywall, quality aftermarket equivalents like Owens Corning or USG perform identically and can trim 8-12% off the material budget. We’ll give you both options in writing.
Styles & brands we work with
Signs Your CertainTeed Home Additions & ADU Is Failing
- Water staining at the roofline or ceiling corners. This usually means the CertainTeed shingle underlayment or flashing has failed at the transition where the addition ties into the original roof. Los Angeles gets most of its rain in a few heavy weeks, so the leak shows up fast when it happens.
- Siding that’s warped, chalky, or pulling away from the wall. CertainTeed vinyl holds up well, but the San Fernando Valley’s 100-degree summers and UV exposure will eventually fade and embrittle any polymer. If you can see gaps at the seams from ten feet away, water is getting behind it.
- Rooms that won’t hold temperature. If your ADU bakes in summer and chills in winter even with the HVAC running, the CertainTeed insulation has likely settled, been chewed by rodents, or was never installed to the right R-value in the first place.
- Drywall cracks along seams where the addition meets the original house. Los Angeles sits on expansive clay soils that shift seasonally. Additions need movement joints at the transition, and if those weren’t framed correctly, the CertainTeed drywall will crack on a regular schedule.
- Rising electric bills without a usage change. Failed insulation doesn’t announce itself, it just costs you money every month. We see this constantly in ADUs built 10-plus years ago with minimal insulation. A thermal camera tells us in 20 minutes where the walls are leaking conditioned air.
Replacement Cost & What’s Included
Here’s what a CertainTeed-spec addition or ADU actually costs in Los Angeles, line by line:
- Full home addition (up to ~600 sq ft): $53,100 – $153,400
- ADU construction (detached, up to ~1,000 sq ft): $106,200 – $259,600
- Garage conversion to ADU: $35,400 – $94,400
- Roof replacement on existing addition (CertainTeed Landmark shingles): $9,440 – $23,600
- New siding on existing addition (CertainTeed Monogram vinyl): $4,130 – $12,980
What drives the range is size, site access, foundation condition, and whether Los Angeles Department of Building & Safety requires engineered plans or seismic upgrades. We deliver a written price before any work starts, and it stays that price unless you change the scope. Every job includes a written guarantee covering our workmanship for 365 days from the completion date. If a repair or install fails within that year, we return and fix it free. No dispute process, no conditions.
We also price KraftMaid cabinetry, Cambria and Silestone countertops where they fit the design of your addition or ADU. Call (213) 632-5711 and we’ll walk you through the numbers for your specific lot and building size.
See the difference
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AfterDIY or Call Us?
You can safely handle three things yourself: measuring your existing addition’s square footage, checking your property’s ADU eligibility with the city, and noting where you’re seeing water stains or temperature problems. That information makes the first call with us much faster.
What you shouldn’t do: attempt to reroof a Los Angeles addition, reframe walls, pull existing siding, or touch any load-bearing element. Steep-roof work and structural changes injure experienced tradespeople every year in this city. One of Isaac Pruett’s hard rules from his LATTC training days: don’t let anyone without a harness and a real plan get on a second-story roof. More practically, we’ve rebuilt several DIY additions where a homeowner saved $8,000 on labor and spent $40,000 undoing the damage. The savings don’t survive contact with a Los Angeles building inspector. If you’re seeing any of the failure signs above, call (213) 632-5711 for a free estimate. You’ll know who’s coming and what it costs before anyone picks up a hammer.
FAQs
A properly framed addition with CertainTeed Landmark roofing and Monogram siding will last 25 to 40 years in Los Angeles before the envelope needs significant work, with the roof typically needing replacement around year 20 to 25 depending on sun exposure and storm frequency. The structure itself, if built to current LA seismic code, will outlive the finishes by decades. Call (213) 632-5711 and we’ll assess what your existing addition still has left.
In many cases yes: roof leaks at flashing points, settled insulation, cracked drywall at joints, and faded or warped siding sections can all be repaired without tearing down the addition. Rebuilding only makes sense when the framing itself has water damage, termite damage, or was never built to code. We’ll give you the repair price and the rebuild price side by side so you can decide.
Most additions take 4 to 7 months from permit approval to final inspection; ADUs typically run 6 to 10 months depending on foundation work, utility connections, and how fast the LA Department of Building & Safety moves on your permits. We include the permitting timeline in our written price and schedule, and we pull every permit ourselves. Call (213) 632-5711 for a schedule estimate on your specific scope.
We don’t warehouse full siding or roofing inventories, but we order CertainTeed Landmark shingles, Monogram siding, and InsulSafe SP insulation direct from LA-area distributors with 5 to 10 day lead times, and we confirm material arrival before we schedule your demo day. Drywall and standard framing lumber we can have on site within 48 hours. Know who’s coming, know what it costs, know it’s guaranteed: everything else is just noise.
Contact Mason Remodeling Co Los Angeles
Planning a CertainTeed-spec addition or ADU in Los Angeles, or dealing with one that’s failing? Call (213) 632-5711 for a free estimate. You’ll get a written price before any work starts, a crew that arrives background-checked and in uniform with photo ID, and a 365-day guarantee on everything we build. That’s the Threshold Standard, and it’s how we’ve done every project since 2004.
Written by Isaac Pruett, Owner, Mason Remodeling Co at Mason Remodeling Co Los Angeles, serving Los Angeles and nearby areas.
