Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
CertainTeed Home Additions & ADU: The Los Angeles Owner’s Guide
Home additions and ADU construction in Los Angeles using CertainTeed building products typically runs $53,100 to $153,400 installed, depending on square footage, foundation work, and the roofing, insulation, and siding systems specified. We stock CertainTeed siding, roofing, insulation, and trim products at Mason Remodeling and our crews install them on ADUs, garage conversions, and room additions across Los Angeles every month. Most owners discover the need for CertainTeed products when an existing addition starts showing water intrusion, drywall cracking at the roofline, or insulation that no longer holds temperature – and by then, the right fix usually means replacing the failed material rather than patching it.
This page covers the CertainTeed side of home additions and ADUs: which products matter, what fails first in Los Angeles weather, and what a complete replacement or new build actually costs. Isaac Pruett and our crew have been doing this work since 2004, and we’ve handled enough CertainTeed installs to know exactly what to check before we give you a written price.
Which CertainTeed Products This Applies To
CertainTeed makes several product lines that play a role in home additions and ADUs, and each has its own compatibility quirks. The big four are CertainTeed siding (MainStreet, Cedar Impressions, Monogram), CertainTeed roofing (Landmark, Presidential Shake), CertainTeed insulation (Optima, InsulSafe), and CertainTeed drywall and trim products. The compatibility gotcha most LA homeowners run into: CertainTeed siding profiles are not interchangeable across product generations. A Cedar Impressions panel from 2010 will not match a 2024 panel even if the color name is the same – the profile depth changed slightly, and the locking edges were redesigned. If you’re trying to match existing siding on an older addition, you either need to source the exact-generation panel or replace the whole elevation, not just a section.
For new ADU construction, we specify CertainTeed Landmark shingles on almost every project in Los Angeles. The reason is simple: Landmark is a Class A fire-rated shingle, and with wildfire zone requirements expanding across LA County hillside neighborhoods like Sylmar, Porter Ranch, and Granada Hills, that rating matters more every year. CertainTeed Optima blow-in insulation is another staple for us on ADU framing – it settles less than older fiberglass batt insulation, and in a city where attic temperatures hit 140 degrees in August, proper insulation between the roof deck and living space is not optional. Mason Remodeling is an independent contractor, not a CertainTeed dealer or affiliate, which means we install what works best for your specific project rather than pushing a single product line.
Styles & brands we work with
Signs Your Existing Addition or ADU Needs CertainTeed-Level Attention
- Water staining around window trim and rooflines. In Los Angeles, the real culprit is often failed CertainTeed flashing details or siding that has shifted after years of thermal expansion. The dry heat breaks down caulk seals, and the winter rains find every opening. If you see staining on ceiling drywall near the roofline, the water is already moving through your insulation.
- Drywall cracking at wall-to-ceiling joints, especially on south-facing walls. Los Angeles additions sit on expansive soil in many neighborhoods – the San Fernando Valley especially. Soil heave pushes the foundation micro-inches, and the framing flexes. If your drywall is cracking in a stair-step pattern, that’s not a drywall problem, it’s a structural movement problem.
- Siding panels with visible warping, fading, or brittle edges. CertainTeed vinyl and polymer siding has a lifespan, and full western sun exposure in Los Angeles shortens it. We regularly see 15-year-old siding in Van Nuys and Reseda that looks 30 years old. Once the panels get brittle, they crack at the nail flanges and start pulling loose in wind.
- Attic or crawlspace temperatures that no longer match the rest of the house. If your addition is always 10 degrees hotter than the original house despite the same AC, your insulation has likely settled, gotten wet, or was never installed correctly in the first place. We’ve done enough tear-outs to say this with confidence: someone building an addition without a permit often skips insulation inspection, and you pay for it forever after.
- Roof shingle granule loss in gutters and at downspout bases. CertainTeed Landmark shingles shed granules over time, but if you’re seeing dark asphalt patches on shingles or heavy granules collecting in your gutters after only 8 to 10 years, the shingles are failing early. That’s usually a ventilation problem – hot trapped attic air cooking the shingles from below – and it means the whole roof system, not just the shingles, needs fixing.
Replacement Cost & What’s Included in Los Angeles
A full home addition in Los Angeles using CertainTeed products across the building envelope runs $53,100 to $153,400. That’s the honest range for permitted work: foundation, framing, roofing, siding, insulation, electrical, plumbing, drywall, and finish. ADU construction runs higher at $106,200 to $259,600 because of separate utility connections, fire-rated assemblies, and Los Angeles Department of Building and Safety’s ADU-specific requirements. Garage conversions in Los Angeles fall between $35,400 and $94,400 depending on whether the existing slab can be reused and how much structural retrofitting the old garage shell needs.
Every Mason Remodeling project gets a written price before any work starts. That’s not a promotion, not a favor, not something we do when you ask nicely – it’s just how we operate. Your written price includes all materials, labor, permit fees where applicable, and disposal. If the scope changes mid-project, we write a change order and you approve it before we do the work. No surprise invoices, no verbal estimates that grow. The completed work is covered by our 365-Day Done Right Promise: if something isn’t right within a year of completion, we fix it at no cost.
See the difference
Before
After
Before
After
Before
AfterDIY or Call Us?
Some of this work is genuinely safe to assess on your own. You can check for visible water staining, feel for drafty areas around windows and doors, and look at your roofline from the ground with binoculars to spot missing shingles or sagging sections. You can also call us and describe what you’re seeing – we’ll tell you honestly whether it’s a “keep an eye on it” situation or a “let’s get someone out” situation. That conversation is free.
Where DIY goes wrong is the actual construction. A room addition in Los Angeles requires permits, engineered plans, and inspections. If you build without permits – something we see often from the cheapest-bid crowd – you end up with a non-permitted structure that your insurance may not cover and that a future buyer’s lender may refuse to finance. The siding, roofing, and insulation are also interdependent: a roofing mistake leaks into the insulation, which saturates the drywall, which grows mold. It’s a chain reaction that gets expensive fast. Call us at (803) 680-2547 and we’ll come look, talk through options, and give you a written price before anything starts.
FAQs
CertainTeed Landmark asphalt shingles typically last 25 to 30 years in Los Angeles when attic ventilation is correct, and CertainTeed vinyl siding typically lasts 20 to 30 years in our climate. Full western sun exposure shortens both lifespans by several years. We’ve seen Landmark shingles fail in 12 to 15 years when the attic wasn’t vented correctly, so the installation matters as much as the product. Call (803) 680-2547 and we’ll assess what you have.
Yes, if the damage is limited to a few panels and you can source the same-generation CertainTeed profile. Matching older panels is the hard part because CertainTeed has changed profiles over the years, and a mismatched panel will be visible from across the street. If we can’t source an exact match, we’ll tell you honestly and quote you for a full elevation replacement rather than a patchy repair. Estimates are free either way.
Most room additions in Los Angeles take 4 to 8 months from first day of demolition to final inspection, and ADUs take 6 to 12 months depending on scope and city permitting timelines. Los Angeles Department of Building and Safety permit review can take 6 to 12 weeks alone. We don’t rush the work, but we also don’t disappear mid-project – the crew that starts your job is the crew that finishes it, and you’ll know exactly who’s coming each day.
We stock common CertainTeed Landmark shingle colors, insulation, and trim profiles at our Los Angeles yard, and we order project-specific siding profiles and specialty products as needed. If you need a specific CertainTeed product matched for an existing addition, we’ll verify the exact product generation before quoting so you’re not paying for something that won’t match. Call (803) 680-2547 and we’ll check availability while you’re on the phone.
Call Mason Remodeling for a Written Price
Before you commit to a CertainTeed home addition, ADU, or a repair on an existing addition, get the numbers in writing. A live person answers our phones 24 hours a day, 7 days a week – no call trees, no voicemail loops. Call (803) 680-2547 to schedule your free estimate. Isaac Pruett will walk the site, check the details that matter, and give you a written price. Know who’s coming, know what it costs, know it’s backed up – everything else is just noise.
Written by Isaac Pruett, Owner, Mason Remodeling at Mason Remodeling, serving Los Angeles and nearby areas.
