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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 using CertainTeed materials, the installed cost typically runs $53,100 to $153,400 depending on square footage, foundation work, and finish level. We install CertainTeed siding, roofing, insulation, and drywall systems on additions and ADUs across Los Angeles, and we stock the most common CertainTeed components on our trucks so the job doesn’t stall waiting on a supply run. Most homeowners discover they need CertainTeed-specific replacement parts when existing CertainTeed siding cracks at the corners, drywall shows stress fractures from settling, or insulation loses its R-value after years of attic heat exposure.
The Carson, Torrance, and Pasadena calls we get usually start the same way: a homeowner has a certain CertainTeed product on the original house and wants the addition to match, or the addition itself is fifteen years old and something’s failing. Either way, you need to know exactly which CertainTeed line you have before anything gets ordered. That’s what this page is for.
Which CertainTeed Models This Applies To
CertainTeed makes a broad range of exterior and interior building products, and the compatibility questions differ by category. For siding on additions, the three lines we see most in Los Angeles are CedarBoards, Monogram, and MainStreet. CedarBoards runs a 6-7/16″ exposure, Monogram is a double 4″ or double 5″ lap, and MainStreet is the narrower 4″ exposure economy line. They don’t interchange, so if your original house has Monogram and you buy CedarBoards for the addition, the shadow lines won’t match and you’ll see it from the street every time.
For drywall, the distinction is between CertainTeed’s standard AirRenew and the mold-resistant M2Tech boards. M2Tech matters in a Los Angeles ADU because detached units without continuous HVAC can hold humidity, and standard gypsum will soak it up. For insulation, the line is CertainTeed InsulSafe or OPTIMA, and the R-value spec depends on whether your ADU falls under the current Los Angeles Title 24 energy requirements, which changed enforcement in 2023. We’ll pull your permit documents and check against what the city approved, not just what the label says.
OEM versus aftermarket: CertainTeed warranties are strong on the roofing and siding side, less so on interior components where the fastener, tape, and compound matter as much as the board. We use CertainTeed OEM where the warranty chain matters and quality aftermarket equivalents where the spec is fungible. We’ll tell you which is which. Bradford Remodeling is an independent contractor and not affiliated with CertainTeed, so our recommendation isn’t steered by any brand rep.
Styles & brands we work with
Signs Your CertainTeed Home Additions & ADU Is Failing
- Cracks running vertically at siding corners. This usually means the siding was nailed too tight in the original install and the panels can’t expand and contract with Los Angeles temperature swings. Once the nail slot tears out, water gets behind the panel and the sheathing starts to go.
- Drywall seams visible under paint, especially on vaulted or cathedral ceilings. The addition’s framing moved, or the original taper didn’t use CertainTeed’s recommended joint system for that board type. A visible seam that’s been painted twice means the tape is delaminating from the board.
- Attic insulation that’s settled to half its original height. CertainTeed blown-in fiberglass shouldn’t settle more than a few inches. If your ADU or addition attic reads 6 inches where the spec called for R-38 at 12 to 13 inches, the space is losing conditioned air every day and your electrical bill is paying for it.
- Soft drywall below windows or at the base of exterior walls. Water got past the building envelope and wicking into the gypsum. In a Los Angeles ADU, this most often traces to a failed window flashing detail or a weep screed that got buried when someone poured a new patio slab too high.
- Roof shingle granule loss concentrated on one slope of the addition. That slope takes the worst of the afternoon sun, and CertainTeed’s three-tab shingles will shed granules faster on that exposure than the rest of the roof. If the gutter has a dark powder line after a rain, the shingles are past their useful life and the underlayment is next to fail.
See the difference
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AfterReplacement Cost & What’s Included
Home additions and ADUs in Los Angeles land between $53,100 and $153,400 installed, and that spread comes down to three things: square footage, site conditions, and finish level. A 400-square-foot single-room addition with a simple gable roof and standard finishes sits at the lower end. A 750-square-foot ADU with a full kitchen, bathroom, foundation work, and upgraded CertainTeed exterior products pushes toward the top. Foundation conditions in Los Angeles change the number fast, especially in hillside zones where piers or caissons are required.
Our written price includes the full scope: demolition if needed, framing, sheathing, CertainTeed insulation and drywall, siding or stucco, roofing, rough-in for plumbing and electrical, interior finishes, and permit close-out. Parts and labor are line-itemed separately so you see exactly what the CertainTeed materials cost versus the labor to install them. The 365-Day Done Right Promise covers the completed work for a full year after the final walkthrough. If something fails inside that window, Bradford Remodeling returns and corrects it at no charge. That promise is in writing before we start, and you’ll have a signed copy at job close.
Straight number, real scope, no surprises at the punch list.
DIY or Call Us?
A homeowner can safely check a few things: find the CertainTeed label on the backside of a siding panel or the edge of a drywall sheet, measure the insulation depth, and note where cracks or seams are showing. That’s useful information to have before you call. What you shouldn’t do is tear out a wall, re-sheath a corner, or open up a roof section on an addition. Framing, electrical, and structural envelope work carry real risk, and a botched patch to an exterior wall creates a moisture path that costs more than the original repair. If you’re looking at structural cracks, water intrusion, or anything involving a bearing wall, call (903) 568-7222 and let a trained crew handle it.
FAQs
CertainTeed vinyl siding typically performs for 25 to 35 years in the Los Angeles climate, and CertainTeed asphalt shingles for 20 to 25 years depending on sun exposure. Coastal fog zones and inland high-heat zones can shorten those numbers. Call (903) 568-7222 for an exact quote on your addition.
Small siding cracks can sometimes be patched, and individual shingles can be swapped, but failed drywall, settled insulation, and structural envelope problems almost always require replacement of the affected section. Patch jobs on water-damaged gypsum always fail again. Call (903) 568-7222 and we’ll tell you which situation you have before anyone touches the wall.
A standard 400-square-foot addition takes 8 to 12 weeks from permit approval to final inspection, and a full ADU takes 4 to 6 months including foundation and utility work. Los Angeles Department of Building and Safety plan-check times add to the front end. Estimates are free, call (903) 568-7222.
We stock the most common CertainTeed drywall, insulation, and siding profiles on our trucks, and we special-order anything outside that inventory within three to five business days. Every material on the quote is documented by brand, model, and spec before work begins. Call (903) 568-7222 to schedule your free estimate.
Written by Curtis Lane, Owner, Bradford Remodeling at Bradford Remodeling, serving Los Angeles and nearby areas.
