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Boral Home Additions & ADU: The San Francisco Owner’s Guide
If you’ve got a Boral home addition or ADU in San Francisco and a component is failing, here’s the straight answer: Bradford Remodeling Co San Francisco installs and services Boral-compatible additions and ADU systems across the city, with complete projects typically running $53,100 to $153,400 depending on square footage, foundation work, and finishes. We diagnose the specific Boral panel, trim, or structural issue, pull the right replacement, and handle it as a full-scope repair or addition rather than a patch job.
Most San Francisco homeowners discover a Boral component has failed the hard way: a hairline crack spreads through an exterior panel after a damp winter, a fascia board shows rot where fog moisture sat against it, or a corner trim piece pulls away from the framing after a few seasons of bay wind. The good news is Boral’s cement-based and polymer products are generally forgiving, but when one fails, it usually means water found a way in. That’s the thing you fix first.
Key Takeaways:
- Full Boral home addition or ADU work in San Francisco runs $53,100 to $153,400
- We identify the exact Boral product line and match it, so repairs blend with your existing structure
- Every job gets a written price before work starts, and the 365-Day Done Right Promise covers the completed work for a full year
Which Boral Models This Applies To
Boral manufactures several product lines that show up on San Francisco additions and ADUs, and they are not interchangeable. The two you’re most likely dealing with are Boral TruExterior siding and trim (a poly-ash product that machines like wood but holds up against moisture) and Boral concrete roof tile, which is heavier than standard asphalt and requires different flashing details at the eaves. If your addition has a flat or low-slope section, you may also have Boral’s lightweight roofing panels specified for that condition.
Here’s the compatibility gotcha: Boral TruExterior trim comes in specific thicknesses, usually 5/4 and 4/4, and the reveal dimensions on older San Francisco projects can differ from what’s stocked now. If you’re patching a Boral fascia board on a home addition built eight or ten years ago, we need to measure the actual reveal, not the nominal dimension. A three-quarter-inch board from the original build may need to be ripped to match, or we may recommend replacing the full trim run so the sight lines stay clean. For Boral concrete tile, the profile and color batch matter. Tile from a different production run can be close but not identical in tone, and on a south-facing ADU wall in San Francisco, that mismatch will show for years.
Bradford Remodeling Co San Francisco is an independent remodeler, not affiliated with Boral. We work with Boral’s distribution network to source OEM material, and we also carry a documented roster of equivalent aftermarket trim and flashing stock where an OEM part is no longer produced. For TruExterior, the aftermarket options are generally solid. For roof tile, we lean OEM because the profile match matters more than the savings.
Styles & brands we work with
Signs Your Boral Home Additions & ADU Is Failing
- Cracks radiating from fastener holes in TruExterior trim. This is the most common failure we see in the Outer Sunset and Richmond District, where fog moisture gets behind the trim and the material swells and contracts against the screw. The underlying cause is usually a failed or missing seal at the fastener point.
- Visible swelling or delamination at the bottom edge of a Boral panel. If water wicks up from grade or splashes back from a patio, the bottom six inches of a panel will start to separate. This is a drainage and clearance issue, not a product defect, and it needs to be corrected before replacing the panel.
- Fascia pulling away from the eave on an ADU. Boral trim is dimensionally stable, so when it moves, the movement is in the framing behind it. On older San Francisco ADUs with original wood framing, this usually means the rafter tails have rot and need repair before the trim goes back on.
- Concrete roof tile showing spider cracking or spalling on the surface. This happens when water gets absorbed into the tile and freezes (rare in San Francisco) or when the tile was walked on during installation. A spalled Boral tile is a water path, even if it hasn’t cracked all the way through.
- Visible gaps at outside corners where two Boral trim pieces meet. This is the classic sign of an installation that didn’t include proper flashing behind the corner. The trim itself rarely fails at the joint; what fails is the water management behind it.
See the difference
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After
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After
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AfterReplacement Cost & What’s Included
For Boral home addition and ADU work in San Francisco, here’s the pricing structure we work from:
- Full home addition (Boral trim and/or siding included): $53,100 to $153,400
- ADU construction: $106,200 to $259,600
- Garage conversion: $35,400 to $94,400
- Boral trim repair or replacement (isolated sections): $4,130 to $10,620 (priced per linear foot and access)
- Boral concrete tile repair on an existing roof: $710 to $2,950 depending on the number of tiles and slope access
What moves the number on a Boral-specific job is scope clarity: are we replacing two pieces of fascia, or are we stripping the entire ADU eaves line and re-flashing it? A $4,000 trim repair usually means one exposed section with good framing behind it. A $10,000 repair means scaffolding, rot repair in the rafter tails, and new flashing throughout the eaves. Every Bradford Remodeling job in San Francisco gets a written price with a line-by-line scope before any work starts. The number does not move at the door. And when the work is complete, you get a signed 365-Day Done Right Promise: if it fails within a year, we come back and correct it at no charge.
DIY or Call Us?
With Boral products, there’s a honest split. On the inspection side, you can walk your addition or ADU once a season and look for the cracking patterns and gapping we listed above. Take photos, measure the affected area, and note which side of the building it’s on. That information helps us quote accurately over the phone.
On the repair side, we draw a firmer line. Boral TruExterior installs fine with standard tools, but the failure you’re fixing is rarely just the visible piece. It’s the flashing behind it, the rot in the framing it was hiding, or the drainage problem that caused the issue in the first place. If you replace the panel without correcting what caused the failure, you’ll do the job again in eighteen months. Roof tile work is outright dangerous, sloped surfaces and heavy tile mean a fall risk that isn’t worth taking on yourself. Curtis Lane has spent two decades reading framing and moisture movement in San Francisco’s older buildings, and he’ll tell you the same thing on the phone: let us look at it before you spend money on materials you may not need. Call (831) 610-5598 for a free estimate.
FAQs
Boral TruExterior carries a manufacturer’s warranty that typically runs 20 years or more, but in San Francisco’s fog belt, the real-world lifespan depends almost entirely on installation quality. Trim installed without proper flashing behind joints will show moisture problems in three to five years; trim installed correctly should last 20+ years without meaningful deterioration. Call (831) 610-5598 if you want us to assess the installation on your existing addition.
A hairline surface crack in Boral TruExterior can sometimes be sealed and monitored, but any crack that has opened more than about a sixteenth of an inch, or any crack at a fastener point, means the panel needs replacement. The issue is that a visible crack means water has been getting behind the panel. Sealing the face doesn’t fix what’s happening behind it. We’ll give you a straight answer on whether repair is even an option before we quote a replacement.
An isolated Boral fascia or trim replacement on a San Francisco home addition typically takes one day. Full ADU eaves line replacement with scaffolding and rot repair usually runs two to three days. Small concrete tile repairs can be done in a morning if we have the matching tile in stock. We’ll give you a written timeline with your written price.
We keep common Boral TruExterior profiles and trim dimensions on hand, along with matching flashing components. For concrete roof tile and less common panel colors, we order through Boral’s distribution network, which adds a few days to the schedule. The written quote will always tell you if material lead time applies before you commit to the job. Call (831) 610-5598 and we’ll check inventory while you’re on the phone.
Written by Curtis Lane, Owner, Bradford Remodeling Co – San Francisco, CA at Bradford Remodeling Co San Francisco, serving San Francisco and nearby areas.
