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Boral Home Additions & ADU: The Los Angeles Owner’s Guide
Boral home additions and ADU construction in Los Angeles typically run between $53,100 and $153,400 for a full addition, while a complete detached ADU lands between $106,200 and $259,600 depending on square footage, foundation work, and finish level. We install and build with Boral-compatible materials daily, and we can get your project scoped and priced in writing before any work starts. Most homeowners call us after their existing addition shows framing issues, or when they realize their current space wasn’t built to Los Angeles seismic and setback codes.
What usually brings people to this page is a failed or failing part of an existing structure: a sagging ridge beam, a rotted sill plate, a door frame that won’t stay square, or a room that was never properly permitted. You want to know whether the Boral component you have can be matched, what the real cost is, and whether you need a crew that understands Los Angeles building codes. We’ll answer all three.
Which Boral Models This Applies To
Boral produces several exterior cladding and trim product lines that appear regularly in Los Angeles home additions and ADUs. The compatible lines we work with include Boral TruExterior siding and trim, Boral Versetta Stone, and Boral roof tiles. Each has its own fastening requirements and expansion behavior. TruExterior, for example, uses a poly-ash substrate that does not absorb water the way fiber cement or wood does, which means it handles Los Angeles’s wet-winter-to-dry-summer swings without swelling or cracking the way cheaper sidings will.
If you have an existing Boral product, identify it before ordering anything. Look for the manufacturer’s stamp on the back side of a trim board or inside a siding seam. Measure the profile thickness: TruExterior trim comes in 4/4 and 5/4 thicknesses, and Versetta Stone panels are 8 inches by 36 inches with a tongue-and-groove locking ledge. One compatibility gotcha we see often: homeowners replace a cracked Boral corner board with treated lumber, not realizing the Boral product was chosen specifically because it doesn’t cup or rot at the mudsill. The aftermarket lumber looks fine for a season, then warps and pulls the siding with it. For Boral-specific parts, OEM matters. For generic framing lumber inside the wall, a quality graded kiln-dried aftermarket equivalent is fine and keeps your budget sane. Bradford Remodeling is an independent contractor and not affiliated with Boral, but we stock and order their product lines through our documented materials roster.
Styles & brands we work with
Signs Your Boral Home Additions & ADU Is Failing
- Gaps opening at outside corners where Boral trim meets siding. This usually means the original installer nailed the trim too tightly and the building’s seasonal movement is now working against the fasteners. In Los Angeles, the temperature swing between a Santa Ana October and a wet February will test every corner joint.
- Water staining on interior drywall below windows or at the ceiling line. Often a failed flashing detail behind Boral trim, not the Boral product itself. The trim is doing its job; the housewrap or flashing behind it wasn’t lapped correctly.
- Boral Versetta Stone panels pulling away from the wall plane. This is almost always an installation error with the locking ledge, not a material failure. The panels are designed to lock together, and when the bottom course isn’t level, every course above it compounds the mistake.
- Popping or squeaking floor systems in the addition. This points to the framing, not the cladding. If the addition was built before current Los Angeles seismic retrofit standards, you may be hearing joist hangers that were never installed or a beam that’s undersized for the span.
- Doors and windows in the addition that stick seasonally or won’t latch. In Los Angeles, this is frequently a foundation issue under the addition: expansive soil in areas like the San Fernando Valley or parts of the Basin expands and contracts enough to shift a poorly anchored mudsill by a quarter inch, which is all it takes to rack a door frame.
See the difference
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After
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After
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AfterReplacement Cost & What’s Included
In Los Angeles, the installed cost for replacing failed Boral exterior components on an existing addition runs from roughly $2,360 to $7,670 for isolated trim and siding repairs, and $4,130 to $12,980 if the failure extends into structural framing or sheathing. If you’re replacing a rotted mudsill or sistering floor joists, expect the project to land in the $5,310 to $14,160 range once you factor in permitting, engineering, and the required Los Angeles Department of Building and Safety inspections.
| Scope of Work | Typical Los Angeles Installed Range |
|---|---|
| Boral trim and siding repair (isolated sections) | $2,360 – $7,670 |
| Full re-clad of a small addition (400 – 600 sq ft exterior) | $8,260 – $21,240 |
| Structural repair including mudsill, joists, or beam replacement | $5,310 – $14,160 |
| New home addition (full build) | $53,100 – $153,400 |
| Detached ADU construction | $106,200 – $259,600 |
| Garage conversion to living space | $35,400 – $94,400 |
Every one of these numbers includes a written price before we start. You’ll see parts and labor separated on the estimate, so you know exactly what the Boral material costs and what the crew costs. The 365-Day Done Right Promise covers the completed work for a full year: if anything we installed fails inside that window, we return and correct it at no charge. That’s written into the contract, not implied.
DIY or Call Us?
You can safely handle the diagnosis on a Boral home additions or ADU problem. Walk the exterior, check for gaps at corners, look for staining, and note which direction any cracks run. If you want to pull a piece of trim to check the condition of the sheathing behind it, that’s within most homeowners’ reach, assuming you’re comfortable with a pry bar and have a ladder on solid ground. What you should not do is attempt structural repairs without a licensed contractor and the right permits. Los Angeles Building and Safety will flag unpermitted structural work when you sell the house, and a botched seismic retrofit it is a safety issue, not just a code issue. If the failure involves any load-bearing member, a gas line, or the electrical panel serving the addition, call a professional. That’s not a caution; that’s the law and common sense.
Call us at (903) 568-7222 if the problem is structural or you’re tired of guessing. We’ll come out, look at the actual condition, and give you a written price. No charge for the estimate.
FAQs
Boral TruExterior siding and trim carries a 20-year limited warranty from the manufacturer, and in Los Angeles’s climate we see it holding its profile and paint adhesion well past 15 years with basic maintenance. The weak point is almost never the Boral product; it’s the flashing, the fasteners, or the housewrap behind it. Call (903) 568-7222 for a free estimate if you suspect installation issues, because those will show up inside the first five years.
Yes, if the damage is cosmetic and confined to the paint or a small surface crack. In that case we can sand, spot-fill with a poly-ash compatible caulk, and repaint. If the board is cracked through at a fastener point or pulling loose from the substrate, replace it. A patched structural trim board will open back up within a season. Call (903) 568-7222 and we’ll tell you which category you’re in.
Isolated trim and siding replacement on a Los Angeles addition is usually a one-day job once materials are on site. Structural repairs involving framing, permitting, or inspection typically run one to three weeks depending on scope and LADBS scheduling. ADU construction is a different animal, commonly 9 to 14 months in Los Angeles from permits to final inspection. We’ll give you a written timeline before work starts.
We keep common Boral TruExterior trim profiles and Versetta Stone starter courses in our Los Angeles materials inventory, along with the correct fasteners and flashing systems for Boral installations. Specialty profiles and larger siding orders come from our documented supplier network, usually in three to seven business days. We’ll tell you at the estimate which parts are on the truck and which are on order.
Straight number, real scope, no surprises at the punch list.
Call (903) 568-7222 for a free written estimate on any Boral home additions or ADU work in Los Angeles. We’ll answer in person, get you a written price, and stand behind the work for a full year.
Written by Curtis Lane, Owner, Bradford Remodeling at Bradford Remodeling, serving Los Angeles and nearby areas.
