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Oldcastle Home Additions & ADU: The Dallas Owner’s Guide
Most Dallas homeowners don’t call us about Oldcastle home additions or ADU construction until something has already gone sideways. They call because a previous contractor walked off mid-project, or the permit got tangled, or a foundation issue showed up after the slab was poured. What they actually need is a straight answer on what it costs to fix or finish the work, and whether anyone in Dallas will touch a half-built addition without making things worse. We do. A home addition in Dallas typically runs $45,000 to $130,000 installed, and an ADU runs $90,000 to $220,000 depending on size, foundation condition, and utility runs. We will walk you through every line item before you commit.
We are an independent Dallas contractor, not affiliated with Oldcastle, and we work with Oldcastle-compatible materials and specifications on additions and accessory dwelling units across the metro. The most common failure points we see are not framing or roofing. They are foundation settlement, tie-in leaks where the new structure meets the old, and undersized HVAC runs that turn a second-story addition into a sweatbox by July. If you are reading this because a previous build is failing, the first thing we do is figure out exactly what is still sound before anyone quotes a number.
Which Oldcastle Models This Applies To
When we say Oldcastle compatibility on a home addition or ADU project in Dallas, we are talking about the materials and systems, not a single product line you would pull off a shelf. Oldcastle’s concrete block, pavers, and masonry products show up in foundation walls, retaining blocks, and hardscape tie-ins. The gotcha we run into constantly: not every concrete block spec is rated for load-bearing in a residential foundation context here. Dallas’s expansive clay soil moves, and a block that worked fine for a garden wall in another region is not necessarily the right block for a stem wall under a bedroom.
If you are matching an existing Oldcastle block or paver, check the visible face dimensions and the core pattern before you call us. We can identify most standard residential units from a photo. For an addition, what matters most is that the new foundation meets the same specification as the original. We typically see 8-inch concrete block for stem walls in Dallas additions, with a minimum 2,500 PSI grout fill in the cores where load-bearing is required. The OEM versus aftermarket decision for Oldcastle products is simpler than it sounds: for structural block, use what the engineer specified on the approved drawings. For decorative pavers, aftermarket equivalents are usually fine if the color and thickness match.
Styles & brands we work with
Signs Your Oldcastle Home Additions & ADU Is Failing
- Cracks stepping through the block or brick at the corners of the addition. This usually means differential settlement. The original house has finished settling, and the new addition is still moving. In Dallas’s clay soil, this shows up most after a wet spring followed by a dry August.
- Doors or windows in the addition that stick seasonally. When the opening is square in January and binds in July, the foundation is moving. This is not a hinge adjustment problem. It is a soil moisture problem under the slab or stem wall.
- Water seeping along the seam where the addition meets the original exterior wall. We see this in Dallas constantly on older homes. The original flashing was never properly tied into the new roofline, or the original contractor used caulk where the detail called for a flashing pan.
- A visible gap opening at the roofline where the addition connects. That gap means the trusses or rafters were not properly anchored to the existing structure. Left alone in a Texas windstorm, that gap will get bigger.
- The addition or ADU runs hot in summer even with the AC running full blast. A room that gains ten degrees by 4 p.m. in a Dallas July typically has an undersized duct run or a return air problem. Retrofitting HVAC after the drywall is up costs more than doing it right the first time.
Replacement Cost & What’s Included
Here is what homeowners in Dallas should expect to pay when fixing, completing, or building these projects with us.
| Scope | Typical Dallas Range |
|---|---|
| Home Addition (finish or build) | $45,000 – $130,000 |
| ADU Construction | $90,000 – $220,000 |
| Garage Conversion | $30,000 – $80,000 |
The spread is driven by square footage, whether the existing structure is sound or needs demolition, and what the utility runs require. An ADU with a bathroom and kitchen on the far side of a lot from the main sewer line is a different job than one built right next to the main house. What is included on every project: a written price before work starts, pulled permits passed through final inspection, and the 365-Day Done Right Promise. If something is not right within a year of completion, we make it right at no cost to you.
See the difference
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AfterDIY or Call Us?
Let me be direct. Foundation repair, structural framing, and tying a new roof into an existing structure are not DIY territory. I grew up in Los Angeles, learned the trade at LATTC, and ran jobs across Southern California before bringing that same methodical approach to Dallas. After two-plus decades in construction, we still walk every job before the first nail goes in, because a plan on paper and a house in front of you are two different things. The patterns we see in Dallas clay, from Oak Cliff to the neighborhoods around the Dallas Market Center, repeat: settlement cracks, tie-in leaks, undersized HVAC. Those are diagnosed with a level, a moisture meter, and years of experience, not a YouTube tutorial.
What you can do safely: document the problem with photos, note when you first noticed it, and pull any original drawings or permits you have. That shortens the diagnostic time when we arrive. Then call us at (432) 302-8761. We will tell you what it costs to fix, and frankly, whether it is worth fixing at all. Some additions we have been asked to repair cost more to correct than they would to tear down. You deserve that honesty before you spend a dollar.
As for working on high-tension or structural elements of a failed addition yourself: springs, roof ties, and foundation stabilization carry real risk of collapse or serious injury. We recommend a trained professional handle any structural work. Do not put yourself under a failing roofline.
FAQs
A properly built addition or ADU should last 50-plus years structurally, though the tie-in details and waterproofing typically need inspection and maintenance every ten years in Dallas’s climate. The biggest threat here is not age. It is seasonal clay movement at the connection points. Call (432) 302-8761 and we can tell you whether your movement is normal or trouble.
Yes, in most cases the failure is at the tie-in points and foundation, not the entire structure. We repair what is failing, replace what is rotten, and preserve what is sound. The only time rebuild is cheaper is when the original framing was so poorly done that opening the walls costs more than starting over. A site visit tells us which one you are dealing with.
Small tie-in and flashing repairs typically take three to five days. Structural foundation repairs add one to two weeks. A full ADU build from bare ground to final inspection usually runs four to six months in Dallas, mostly depending on city permitting timelines, which we handle for you. We put the schedule in writing before we start.
We source what the job requires, and we maintain working relationships with suppliers for concrete block, pavers, and masonry materials compatible with Oldcastle specifications across the Dallas area. We also work with spec-grade partners including KraftMaid, Cambria, and Silestone when the job involves cabinetry, countertops, or finishes. You get the right material, not whatever is on sale at the yard.
Call Mason Remodeling Co Dallas
You should know who is coming, what it costs, and what happens if something goes wrong, before we ever pick up a tool. That is how we have worked since 2004, and Isaac Pruett still walks every job himself. We provide a written price before any work starts, and every crew member who arrives at your door has been background-checked, identity-verified, and introduced by name and photo before the visit. If you need a straight answer on a failing addition or ADU in Dallas, call (432) 302-8761 for a free estimate.
Written by Isaac Pruett, Owner, Mason Remodeling Co Dallas at Mason Remodeling Co Dallas, serving Dallas and nearby areas.
