Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
Master Halco Home Additions & ADU: The San Antonio Owner’s Guide
Master Halco home additions and ADU projects in San Antonio typically run between $45,000 and $130,000, depending on square footage, foundation work, and how far the existing roofline has to move. We install and finish these additions with named-brand materials and a written price before any work starts. Most San Antonio homeowners discover their addition plans need adjustment when an existing roofline, slab, or permit condition doesn’t line up with the original Master Halco product specifications they pulled online, and they need someone who can read the measurements and tell them exactly what will and won’t work. Graham Stein and our crew have walked through enough King William Historic District properties to know that older San Antonio homes rarely match any catalog sheet perfectly.
We’re an independent San Antonio remodeling contractor, not a Master Halco dealer or affiliate. That matters because we can spec a Master Halco-compatible room addition or ADU shell without pushing you toward a single product line. If your plans call for cabinets from KraftMaid, countertops from Cambria or Silestone, and windows from James Hardie, those names all work inside a Master Halco-framed addition, and we’ll write that down in the scope before demo day.
Which Master Halco Models This Applies To
Most San Antonio homes asking about Master Halco additions are working from one of three product categories: the standard gable-end room addition kits, the attached ADU shells with a shared wall, or the detached accessory dwelling unit frames that Master Halco sells through local lumber yards across Texas. Each category uses different connector plates, header schedules, and anchor bolt patterns, and mixing up the hardware between them is the most common ordering mistake we see. The model label is usually stamped on the bottom chord of a truss or on the end of a header beam, but on San Antonio homes built before 2000, that label has often faded past reading.
If the label is gone, we measure the spacing: Master Halco room addition kits historically ship with 16-inch on-center stud layout for the gable kits and 24-inch for the detached ADU shells, but the San Antonio climate has pushed a lot of builders toward 16-inch on everything to handle the summer sun load on the roof deck. OEM Master Halco hardware is worth paying for when it’s a load-bearing connector or hurricane tie, because the zinc coating is specced for coastal humidity and Texas isn’t always content to stay dry. For non-structural blocking and trim, a quality aftermarket equivalent from a San Antonio lumber yard will carry the same load ratings and cost less than OEM. The decision we always write into the price: where the part carries weight, use Master Halco. Where it just fills space, use what the inspector will accept and save the family money.
Styles & brands we work with
Signs Your Master Halco Home Additions & ADU Is Failing
- Doors that stick in summer but swing fine in winter. San Antonio’s clay soil expands and contracts with moisture, and a Master Halco addition on a pier foundation will move enough to bind a door in August. The fix is usually a foundation-level adjustment, not a new door slab.
- Cracks running diagonally from the corners of windows or doors in the addition. This points to shear movement between the Master Halco frame and the original house, often where the tie-in detail wasn’t flashed or framed with enough overlap. The crack itself isn’t the problem; the movement behind it is.
- A visible gap where the addition roof meets the main house roof. San Antonio’s afternoon thunderstorms will drive water into that gap fast. The flashing detail Master Halco specs in the kit is correct, but if the original installer substituted a cheaper saddle or skipped the step flashing, the gap opens up within a few seasons.
- Drywall screws popping along the ceiling of the addition. This usually means the Master Halco trusses were stored too long before installation and picked up enough moisture to shrink after the drywall went up. It’s cosmetic but it’s a sign the wood wasn’t as dry as it should have been.
- Musty smell inside the addition after a heavy rain, with no visible leak. Water is getting behind the siding or into the wall cavity, and in San Antonio’s August heat, that moisture turns to rot fast. We find this most often on additions where the house wrap was torn during install and nobody taped it.
See the difference
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AfterReplacement Cost & What’s Included
Full home additions in San Antonio run $45,000 to $130,000. A detached ADU construction project runs $90,000 to $220,000. A garage conversion, which often pairs with a Master Halco frame for the new roof span, lands between $30,000 and $80,000. What drives the range: foundation type (slab on grade costs less than pier and beam when we’re tying into San Antonio’s expansive clay), whether the existing HVAC can carry the added square footage, and how much of the original roof structure has to come off to tie the new framing in cleanly.
Every price we give includes the written scope, the Master Halco-compatible framing and hardware, the flashing and weather barrier, the named-brand finishes you choose, and the clean-up photo before the crew leaves. Shoe covers and drop cloths are on the job from day one, not billed as a line item. The written price is the price. If something changes mid-project, you’ll see it in writing and approve it before anyone picks up a tool. Our 365-Day Done Right Promise covers every completed addition and ADU: if something isn’t right after we’re done, we make it right.
DIY or Call Us?
What you can safely check on your own: whether the addition’s gutters are clean and draining away from the foundation, whether the crawl space vents are open in summer, and whether the exterior caulk at windows and siding joints has pulled away. Those are observational checks. What you should not do yourself is pull back siding to inspect the Master Halco tie-in framing, cut into a roof-to-wall intersection to check flashing, or attempt to re-shim a foundation pier. Those involve load-bearing structure, and in San Antonio’s shifting soil, guessing wrong means the wall you opened now supports less than it did this morning. If you see cracks, gaps, or sticking doors in a Master Halco addition, call us at (432) 233-0976 and we’ll come look before you move anything.
FAQs
A properly flashed and tied-in Master Halco addition should last 40 to 60 years in San Antonio, with the roof deck and flashing needing replacement at roughly the 20-year mark. The frame itself holds up, but the South Texas sun and summer humidity punish everything that faces the weather. Call (432) 233-0976 and we’ll give you an honest read on what’s salvageable.
Yes, in most cases the framing can be reinforced, the flashing corrected, and the tie-in rebuilt without a full teardown. The exception is widespread wood rot from long-term water intrusion, which in San Antonio’s climate means replacement is often cheaper than piecemeal repair. We’ll tell you which one you’re looking at, in writing, before anything is signed.
A flashing correction or foundation shim takes two to four days once we have the permit in hand. A full tie-in rebuild or roof structure replacement runs two to six weeks depending on scope and San Antonio permitting timelines. The written schedule we give you at contract is the schedule we work to, and we’ll call if anything shifts.
We keep common Master Halco-compatible connectors, hurricane ties, flashing profiles, and anchor hardware on our trucks, and we source the rest from San Antonio lumber yards the same day. For larger structural components we order from the local Master Halco distributor and stage delivery to match the project schedule, so the lumber doesn’t sit in the sun longer than it has to.
Written by Graham Stein, Owner, Elmstead Remodeling San Antonio at Elmstead Remodeling San Antonio, serving San Antonio and nearby areas.
