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Oldcastle Home Additions & ADU: The Austin Owner’s Guide
If you have an Oldcastle home addition or ADU component that’s failing, Mason Remodeling Co Austin stocks and installs Oldcastle-compatible materials for a complete replacement. Most Austin homeowners pay between $45,000 and $130,000 for a full home addition, and $90,000 to $220,000 for an ADU, depending on size, foundation work, and finishes. We’re an independent Austin contractor, not affiliated with Oldcastle, but our crews work with their products weekly and can usually assess the damage and give you a written price within a few days of your call.
The way most people discover an Oldcastle addition or ADU component has failed isn’t dramatic. A corner of drywall starts pulling away. A door that used to latch clean now sticks. Water shows up near the stem wall after a hard rain. In Austin, the clay-heavy soil under most neighborhoods means the structure moves before the finish materials do. By the time you see the crack, the load path has already shifted.
Which Oldcastle Models This Applies To
Oldcastle manufactures a broad line of concrete and masonry building products, and when we talk about “Oldcastle home additions and ADUs” in Austin, we’re typically dealing with two categories. First, the foundation and structural block: Oldcastle concrete masonry units (CMUs), retaining wall block, and precast concrete components used in addition foundations, stem walls, and ADU slabs. Second, the finish products: Oldcastle pavers and wall stone that make up patios, walkways, and skirting around the structure.
The compatibility gotcha that matters here: Oldcastle block comes in both modular (8x8x16 nominal, actually 7-5/8″ x 7-5/8″ x 15-5/8″) and non-modular (true dimension) sizes. If your original addition was built with modular block and someone patches it with non-modular, the courses stop lining up within three rows and you get horizontal drift that shows through the veneer as stair-step cracking. We check the existing block with a tape measure before we ever quote a repair. It’s the kind of detail that separates a lasting fix from one that looks right for six months.
For OEM versus aftermarket: Oldcastle’s structural block has no real “aftermarket” equivalent worth buying. The compressive strength rating (usually 1,900 to 2,800 psi for non-load-bearing, 3,000+ for load-bearing) matters, and off-brand block often skips the testing documentation. For pavers and wall stone, we stock Oldcastle-compatible alternatives from Belgard and Techo-Bloc that match the dimensions and color families well enough for seamless patches. But we’ll tell you honestly when an exact Oldcastle match is worth sourcing versus when a compatible product gets you there faster and for less.
Styles & brands we work with
Signs Your Oldcastle Home Additions & ADU Is Failing
- Stair-step cracks in the block veneer or CMU walls. This is the classic Austin sign of differential settlement. The clay soil under the addition expands and contracts with seasonal moisture, and one corner of the addition moves more than the other. The crack follows the mortar joints because mortar is weaker than the block.
- Doors and windows inside the addition start binding or won’t stay closed. When the foundation shifts, the rough openings rack slightly. A door that scrapes the jamb in summer but closes fine in winter is a settlement signal, not a hinge problem.
- Water staining or efflorescence (white chalky residue) on the block wall exterior. This means water is wicking through the CMU. In Austin’s wet springs, that’s often a weep hole or flashing issue at the stem wall level, not so much the block itself. But left alone, it’ll spall the face off the block over five to ten years.
- Gaps opening between the new addition and the original house. Oldcastle CMU additions settle differently than a wood-framed original structure. When the gap between the addition and the original house starts to widen past 1/4″, the connector details at the roofline and wall plane are failing.
- Pavers or wall stone around the ADU heaving or sinking at the edges. Around Austin, this usually traces back to poor base preparation or a gutter downspout dumping water at the paver edge. It erodes the base material, and the pavers follow. You’ll see a low spot that pools water after rain, which accelerates the problem.
See the difference
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AfterReplacement Cost & What’s Included
The installed price range for Oldcastle home additions and ADU work in Austin runs from $45,000 to $130,000 for a home addition and $90,000 to $220,000 for an ADU, depending on whether you’re looking at structural repair, full replacement of a failed component, or a complete ground-up build. Here’s how the specific costs break out in this market:
- Home Addition: $45,000 – $130,000
- ADU Construction: $90,000 – $220,000
- Garage Conversion (common ADU path in Austin): $30,000 – $80,000
- Foundation / structural block repair on existing addition: typically $8,000 – $25,000 depending on the number of piers and linear feet of wall involved
What drives the range is honest and straightforward: site access, soil conditions on your specific Austin lot (the clay along the Colorado River corridor behaves differently than the limestone pockets west of MoPac), whether the existing footings meet current code or need supplemental support, and the finish level you spec. Every quote we write includes the parts, labor, dump fees, and permits as separate line items. No verbal handshake numbers. No “we’ll figure it out as we go.”
Everything we install is covered by our 365-Day Done Right Promise. If something isn’t right within a year of completion, we make it right at no cost to you. That’s the whole promise, stated plainly.
DIY or Call Us?
Some things an Austin homeowner can safely check before calling us. You can look for the symptoms listed above. You can check your downspouts and make sure they’re not dumping water at the base of the addition. You can measure a crack with a pencil mark and a date, then watch whether it grows over a few weeks. That information helps our crew when they arrive.
What you should not do is try to shore up, jack, or patch structural CMU on your own. Block walls under load can fail suddenly if you remove the wrong section. Mortar removal near a load path isn’t a weekend project. And paver repairs around an ADU foundation that have drainage failure at the root will just sink again in the next Austin monsoon season. That’s when you call us at (903) 623-1966. Isaac Pruett will look at photos, talk through what you’re seeing, and tell you straight if it’s worth a service visit or if you can watch and wait.
FAQs
A properly built Oldcastle CMU addition or ADU in Austin should last 60 to 80 years before major structural work, though finish materials like pavers, caulking, and flashing typically need attention every 15 to 20 years. The wildcard in this city is the foundation soil, which can shorten or lengthen that timeline significantly depending on drainage. Call us at (903) 623-1966 and we’ll tell you what we’re seeing in your neighborhood.
In most Austin cases, yes, the damaged section can be repaired without rebuilding the entire addition. We’ll isolate the failed block, address the underlying drainage or settlement issue, and rebuild the section with matching Oldcastle or compatible materials. Full replacement only makes sense when the damage is widespread or the original construction doesn’t meet current code. Call us for an honest read on your specific situation.
Most structural block repairs on Austin additions take 3 to 10 working days, depending on the scope and whether new footings or piers are required. Paver and wall stone repairs around an ADU usually wrap up in 2 to 4 days. When we quote the job, we’ll give you a working timeline and tell you what could realistically change it. Call (903) 623-1966 to schedule.
We stock Oldcastle-compatible CMU block, mortar, and a range of Oldcastle-compatible pavers and wall stone, and we can source exact Oldcastle matches through our supplier network when the job calls for it. You don’t need to buy anything yourself. We handle the materials, delivery, and any color or size matching before we start.
If your Oldcastle home addition or ADU is showing signs of failure, the fastest way to a straight answer is a phone call. Tell us what’s wrong with it. We’ll figure out what it actually needs. Call (903) 623-1966 for a free estimate, and we’ll put the price in writing before any work starts. We also work with KraftMaid cabinetry, Cambria and Silestone surfaces on the interior side of our addition and ADU builds.
Written by Isaac Pruett, Owner, Mason Remodeling Co Austin at Mason Remodeling Co Austin, serving Austin and nearby areas.
