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Boral Home Additions & ADU: The Fresno Owner’s Guide
A Boral home addition or ADU in Fresno typically runs $45,000 to $130,000 installed, and we can usually get a written price in your hand within a few days of walking the site. The most common reason homeowners call us is a failing roof system or a wall assembly that wasn’t tied into the existing structure correctly, so water gets where it shouldn’t and the whole addition starts working against the house instead of with it.
If you already have a Boral addition on your property and something’s off, that’s a different conversation. You’re dealing with a specific problem now, and you need a contractor who can diagnose the exact failure and give you a real number to fix it. We’re an independent remodeling contractor in Fresno, not affiliated with Boral, but we work on these structures regularly and we know how they’re supposed to be put together.
Key Takeaways:
- Typical Boral addition or ADU project: $45,000 – $130,000 in Fresno
- Most failures start at the roofline tie-in or the foundation connection point
- We write the price down before work starts, and it doesn’t move at the door
- Every project carries the 365-Day Done Right Promise in writing
Which Boral Models This Applies To
Boral’s exterior cladding and trim systems are the pieces we see most often on Fresno additions, and the compatibility question usually comes down to which profile was used. Boral’s TruExterior siding and trim come in specific profile depths, most commonly 5/8-inch and 1-inch nominal thicknesses, and you can’t just swap a different profile into the same reveal and expect the lines to read true. The reveal, or the visible face of each board, sets the whole pattern, and mixing profiles off by even a quarter inch shows up as a crooked wall from the street.
When we take on a repair or an addition that ties into existing Boral siding, we match the exact profile and the original installation method. That means checking the fastener pattern, the substrate condition underneath, and whether the original crew used the right gap for expansion. In Fresno’s heat, siding expands. Boral’s poly-ash material handles it better than wood, but only if it was gapped correctly at the seams. If it wasn’t, you’ll see buckling at the butt joints by August.
The OEM-versus-aftermarket decision for Boral comes down to this: for structural or weather-exposed components, we use OEM Boral product. For interior trim or non-critical visual pieces, a quality aftermarket equivalent that matches the profile depth and paint retention spec can work. But we document what we’re using and write it into the estimate, so you know exactly what’s going on your house.
Styles & brands we work with
Signs Your Boral Home Additions & ADU Is Failing
- Water staining at the roofline tie-in. This is the number one failure point on any addition. The flashing detail between the new roof and the existing house gets done wrong or skipped entirely, and every rain season pushes water behind the wall. In Fresno, it doesn’t rain much, but when it does, it finds the gap fast.
- Gaps opening at siding butt joints. If the original installer butted the Boral boards tight instead of leaving the specified gap, heat expansion forces them against each other and you get buckling, popped fasteners, or visible gaps when the material contracts at night. It looks like a material problem. It’s actually an installation problem.
- Soft spots or spongy feel underfoot near the addition’s foundation line. This usually means the foundation was poured without proper drainage or the soil wasn’t compacted. Fresno’s hardpan expands and contracts with moisture, and a slab that wasn’t prepped for it will crack and heave.
- Doors or windows in the addition that stick seasonally. This is the structure moving. Some movement is normal, but a door that only closes in winter or a window that jams every August means the framing or the foundation isn’t holding square.
- Caulk lines that keep splitting at trim intersections. When caulk fails repeatedly in the same spots, the trim is moving too much. The caulk isn’t the problem. The movement behind it is.
See the difference
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After
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AfterReplacement Cost & What’s Included
For a full Boral addition or ADU project in Fresno, the range is $45,000 to $130,000. The spread comes from size, foundation work, roof complexity, and how much of the existing house has to be opened up to tie everything together properly. A detached ADU with its own foundation and utility runs is going to land at the higher end. A bump-out off an existing room with simple roof lines stays lower.
What’s included in that number: all demolition and site prep, foundation work, framing, roofing, exterior cladding matched to your existing Boral product, windows and doors, rough-in for electrical and plumbing, insulation, drywall, and finish trim. Every line item is written down before we start, and the price doesn’t move unless you change the scope. You get the written price in your hand, signed, before the first tool comes out. That’s The Garrison Standard, and it’s not negotiable.
Every project carries the 365-Day Done Right Promise. If the work fails inside that window, we come back and fix it at no charge. You get that in writing too.
DIY or Call Us?
For a Boral addition failure, there’s a small list of things you can check safely, and a much bigger list of things you should absolutely not attempt yourself. You can check caulk lines, look for obvious gaps at siding seams, and mark where water stains appear after rain. That information helps us diagnose faster.
What you shouldn’t do is pull siding off to inspect the substrate, open up any wall cavity, or try to re-flash a roofline from a ladder. The moment you expose the weather barrier or the flashing, you own whatever happens next, and a wrong fix on a wall assembly means rot you can’t see until it’s structural. If the roofline tie-in is the problem, that’s a job for a crew with the right equipment and a written scope. Call (559) 785-2712 and we’ll walk the site and tell you exactly what’s wrong and what it costs to fix.
FAQs
A properly installed Boral addition should give you 30 to 50 years on the exterior cladding and trim, assuming the substrate was prepped right and the flashing details were done correctly. The structure underneath should outlast that. What shortens that lifespan in Fresno isn’t the Boral product, it’s the sun and the hardpan soil. UV exposure beats on the finish, and soil movement stresses the foundation. If the original install was square and the drainage right, you’ll get the full lifespan. If not, problems show up in the first five years.
Yes, in most cases the failing piece can be isolated and fixed without tearing the whole addition down. A roofline tie-in can be re-flashed, a section of siding can be pulled and reinstalled with proper gapping, and foundation heave can be addressed with drainage correction. The question is how much damage already happened behind the failure. Call (559) 785-2712 and we’ll tell you what we’re actually looking at, not what we hope it is.
A focused repair, like re-flashing a roofline or replacing a failed siding section, takes one to three days once materials are on site. A full addition or ADU runs eight to sixteen weeks depending on scope and permit timing in Fresno. We write the schedule into the estimate along with the price, and we stick to both.
We keep the common Boral trim profiles and flashing materials on hand, but every addition is different and most projects need a specific order. We source OEM Boral product for anything weather-exposed, and we document the exact material and spec in your written estimate. Same goes for the other brands we work with regularly: KraftMaid cabinetry, Cambria and Silestone countertops. We don’t guess on materials, and we don’t leave the spec blank. Call (559) 785-2712 for an exact quote, and we’ll put it in writing.
Written by Curtis Lane, Owner, Bradford Remodeling Co Fresno at Bradford Remodeling Co Fresno, serving Fresno and nearby areas.
