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CertainTeed Home Additions & ADU: The Austin Owner’s Guide
If you’re planning a home addition or ADU in Austin and you want CertainTeed materials specified from the first framing inspection to the final walkthrough, we’ll price it in writing before any work starts. A full home addition in Austin typically runs $45,000 – $130,000, while a detached ADU lands between $90,000 – $220,000 depending on square footage, foundation type, and finish level. Most owners come to us after a smaller remodel went sideways: a contractor vanished mid-project, a “simple” garage conversion turned into an unpermitted mess, or a price that was “around $60,000” somehow became $90,000 once the slab was poured.
We’re not affiliated with CertainTeed, but we specify their products where they hold up best in Central Texas: their siding, insulation, and roofing components perform well through Austin’s heat-soak summers and the occasional February ice event. If you’ve been burned before, this page will tell you what the materials actually cost, what the labor actually costs, and what we put in writing so the number on day one is the number on the invoice.
Which CertainTeed Products Matter for Additions & ADUs
CertainTeed makes a broad line of building products, and the compatibility question changes depending on what you’re adding. For a stick-built addition, the materials that matter most are CertainTeed’s vinyl and polymer siding lines, their insulation batts and rigid foam boards, and their roofing shingles if you’re tying into the existing roof plane. For a detached ADU, you’re looking at the same suite plus their drywall and backer board products, which we install alongside other trade brands like James Hardie siding and Therma-Tru doors.
Here’s the compatibility gotcha most Austin owners don’t know: if your existing home has CertainTeed siding installed before roughly 2015, the specific color lot and profile may be discontinued. You can’t always match an old panel exactly. We address this upfront by pulling a physical siding sample from your exterior and putting it against current CertainTeed stock before we write your quote. When an exact match isn’t available, we’ll show you the closest profile and color side by side so you can make the call with your eyes, not a brochure.
OEM versus aftermarket matters less with CertainTeed than with, say, a gas furnace part. CertainTeed’s products are the original material, and what fails on a home addition isn’t usually the CertainTeed product itself. It’s the flashing around it, the substrate behind it, or the installation that was never done to spec. A cheap aftermarket siding panel isn’t the risk. A crew that skips house wrap behind the panel is the risk. We install CertainTeed products to manufacturer spec because the material warranty only holds if the install is right.
Styles & brands we work with
Signs Your Home Addition or ADU Plan Is About to Go Wrong
Most failed additions aren’t failed by materials. They’re failed by planning. Here’s what we see in Austin:
- You have a verbal estimate and no written scope. The contractor says “somewhere around $70K” and starts demo. Without a written line-item price, that number will drift. Every Penhallow project gets a written price before work starts. That’s the Kingswell Way, and it’s non-negotiable.
- Your existing foundation wasn’t evaluated. Austin sits on expansive clay. Parts of town east of I-35 have soil that moves enough to crack slab foundations within a decade. Before we frame a single wall, we check what the addition is sitting on. Skipping this step is how you get a 400-square-foot room with a door that won’t close by September.
- The permit conversation is vague. A contractor who says “we can probably do this without pulling permits” is telling you they don’t want an inspector looking at their work. Additions and ADUs in Austin require permits, full stop. We pull them, we schedule the inspections, and we don’t close the wall until it passes.
- The price doesn’t include the tie-in. Tying a new roofline into an existing one, matching siding, running new HVAC ducting, upsizing your electrical panel. These are real costs. A quote that ignores them is a quote that changes. We account for tie-in work in the written price, because that’s where additions bleed money.
- You’re hearing nothing about drainage. An addition changes how water flows around your foundation. If your contractor hasn’t mentioned grading or gutters, they haven’t thought it through. We specify drainage on every addition and ADU we quote. It’s a few thousand dollars that saves a cracked slab and a mold problem in a decade.
See the difference
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AfterReplacement Cost & What’s Included
Home additions in Austin run $45,000 – $130,000. ADUs run $90,000 – $220,000. The spread is driven by five things: square footage, foundation type (slab-on-grade versus pier-and-beam), whether you’re adding a bathroom or a full second kitchen, the finish level of the interior, and how much site work the lot requires before we can even form up the slab.
Here’s how Austin pricing breaks down in practice:
- Small bump-out addition (120 – 200 sq ft): $45,000 – $75,000. A single room, no plumbing, existing foundation extended.
- Mid-size addition (200 – 500 sq ft with a bathroom): $75,000 – $110,000. Includes plumbing, new foundation section, roof tie-in, HVAC extension.
- Large addition (500+ sq ft with kitchen or primary suite): $110,000 – $130,000+. Full electrical subpanel, new HVAC zone, structural engineering.
- Garage conversion ADU: $30,000 – $80,000. Lower end if the slab and roof are sound. Higher end if the garage was built before 1980 and needs stem walls, insulation, and a full re-roof.
- Detached ADU (400 – 800 sq ft): $90,000 – $220,000. New foundation, new utility runs from the street or main house, full kitchen and bath, separate HVAC.
Every quote includes the written 365-Day Done Right Promise. If the work fails inside the guarantee period, we come back and fix it at no charge. That’s in writing on every project. No verbal reassurances, no “we’ll take a look” stories. We put it on paper.
DIY or Call Us?
An honest answer: additions and ADUs are not DIY territory. This isn’t a faucet cartridge or a cabinet door you can re-order. You’re dealing with structural engineering, electrical loads, plumbing runs, and Austin’s permitting office. A mistake in any one of those systems creates a problem that costs more to fix than the original job was worth.
What you can do before calling anyone is useful. Measure your lot to understand setback requirements. Pull your survey if you have one. Look at your electrical panel and see if you even have two open breaker slots. Those three pieces of information will make any honest contractor’s first visit more productive. Trevor Nash says it plainly: tell me what you need, I’ll tell you what it costs, and we’ll go from there. Call us at (325) 225-5429 and that’s exactly how the conversation goes.
FAQs
Plan on 3 – 6 months for a mid-size addition and 6 – 12 months for a detached ADU, from permit approval to final walkthrough. Austin’s permitting office adds 4 – 8 weeks at the front end regardless of contractor, and inspections are scheduled on the city’s timeline, not ours. We give you a defined arrival window for our crew, and we keep the site clean the whole way through.
Often yes, and it’s the smarter money. If the foundation is sound and the framing is dry, we can re-side, re-roof, and remodel the interior for less than a full teardown. The first thing we do is check what’s structural versus what’s cosmetic. If it’s cosmetic, you’re looking at a remodel, not a replacement. If the slab has failed or the roof is sagging, that’s a different conversation.
Yes, on every single project. No exceptions. We pull the permits, schedule the inspections, and we don’t cover up framing, plumbing, or electrical until the city sign-off comes through. A contractor who offers to skip permits is not saving you money. They’re making your house harder to sell and your insurance harder to claim.
We source CertainTeed siding, insulation, and roofing materials through our local Austin supply partners rather than warehousing them ourselves. That means you get current stock, correct color lots, and materials that haven’t been sitting in a Texas storage yard for two summers. We also work with KraftMaid, Cambria, and Silestone for the interior finishes, so the same written-price approach applies to cabinets, countertops, and tile as it does to the framing.
If you’re ready to price an addition or ADU in Austin, call (325) 225-5429. You’ll get a real person, a real appointment window, and a written number before anything gets built. That’s the only way we work.
Written by Trevor Nash, Owner, Penhallow Remodeling Austin at Penhallow Remodeling Austin, serving Austin and nearby areas.
