Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
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AfterFast, Reliable Home Additions & ADU Across Upland
A home addition in Upland typically runs $45,000-$130,000, while a detached ADU runs $90,000-$220,000 depending on site conditions, finishes, and whether your parcel falls into the Alquist-Priolo fault zone. Most projects we take on in Upland require a site visit before we’ll put a number in writing, because the difference between a flat lot in 91786 and a hillside lot in 91784 changes everything about the foundation, the grading, and the permit path. If you’re planning a room addition, second story, or ADU in Upland, call (877) 610-1318 and we’ll schedule a free estimate with no trip charge inside the county.
Why Barrett & Sons Construction Is Upland’s Preferred Home Additions & ADU Company
Tom Barrett founded this company in 1998, and his sons run the crews. That matters in Upland because the work we take on here, especially in 91784, requires a level of coordination with geotechs, city plan checks, and hillside grading rules that national outfits treat as a headache. We treat it as the job. When you call our Home Additions & ADU team, you’re not getting a call center. You’re getting Tom’s people, and Tom lives close enough to shake your hand at the hardware store on Saturday.
We’ve worked on post-war tract homes in south Upland where the original slab is fifty years old and the framing was never designed for a second story. We’ve worked on custom foothill homes off Mountain Avenue where the driveway climbs a hundred feet before you reach the front door. The permits are different, the engineering is different, and the schedule is different. We plan for all of it on day one, not when the inspector flags it on week six.
Every price change on a Upland job arrives as a written change order before work proceeds. Every eligible job has permits pulled and inspections signed. And every job, from a 400-square-foot addition to a full detached ADU, carries the 90-Day Done Right Promise in writing. One call brings Tom back.
Our Home Additions & ADU Services in Upland
ADU Design & Permitting
Before we draw a single line, we check your parcel against Upland’s Alquist-Priolo fault zone maps, zoning overlays, and hillside grading requirements. That matters most in 91784, where lots near the mountain front may sit inside the study zone for the Cucamonga Fault. If yours does, the city will require a fault-rupture study before a permit is issued. We coordinate the geotech, the architect, and the city’s plan check so that requirement doesn’t surprise you at week ten. This is the part of the job where most Upland ADUs either move forward on schedule or stall for months. We handle it up front.
Garage Conversion ADU
Converting a garage in Upland’s 91786 tract neighborhoods is often the most cost-effective ADU path, typically $30,000-$80,000. These 1950s-1970s garages are usually detached or attached on slab-on-grade, which simplifies the structural work. The variables are electrical service, sewer line access, and whether the existing slab meets current insulation and stormwater requirements. We pull the permits, bring the structure up to code, and keep the exterior looking like it belongs on your street.
New Detached ADU
A new detached ADU in Upland runs $90,000-$220,000. In 91784, that number swings toward the high end when the lot is sloped, the soil is alluvial fan material, and retaining walls or engineered grade beams are required. On a flat 91786 lot, the cost is friendlier but the permitting still takes coordination with Upland’s building division. We’ve built ADUs of 600 square feet and ADUs of 1,200 square feet in Upland, and the common thread is this: the price gets fixed in writing before the first footing is poured, and any scope change arrives as a written change order before work begins.
Junior ADU & Interior Conversion
A junior ADU is a smart fit for Upland homeowners who have an existing bedroom, den, or office suite that can be converted without adding square footage. These projects run lower than a full ADU because they work within the existing footprint. The catch in older Upland homes is often electrical service, egress, and fire separation between the JADU and the main house. We handle those code requirements and make sure the final space qualifies as legal living area, not just a bedroom with a mini-fridge.
What happens when you call
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A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Upland
On high-end additions and ADUs in Upland, the materials schedule drives the project calendar. We install Simonton and Ply Gem windows and doors on most of our Upland builds, and we order early because lead times on custom sizing run 6-12 weeks from those manufacturers. If a designer on your Upland project specifies PGT impact-rated glass or a specialty door package, we source it through our regular suppliers and confirm delivery dates before we sequence the framing. No mystery brands off a van. Everything we install is a named product you can look up.
Common Home Additions & ADU Problems We See in Upland Homes
- Alquist-Priolo fault zone surprises in 91784. Homeowners start design, get excited, and find out at plan check that their parcel triggers a mandatory fault-rupture study. That adds three to six weeks and several thousand dollars before a footing is poured. We check the map before design starts.
- Fifty-year-old slabs in south Upland. Many post-war tract homes in 91786 were built on unreinforced slab-on-grade with aging sewer lines beneath. Adding square footage often means cutting into the slab, which means discovering what’s under it. We plan for that reality, not around it.
- Hillside lots with retaining wall complications. In 91784, an addition on a sloped alluvial-fan lot routinely needs an engineered retaining wall or grade beam before vertical framing can begin. That changes the excavation scope, the drainage plan, and the budget. Contractors who bid these lots like flatland jobs lose money, and the homeowner pays for it in change orders.
- Long-lead millwork and glass delays. Custom cabinetry and architectural glass on a north Upland project can run 10-16 weeks from order date. If the schedule is built around labor availability instead of material lead times, the job stalls mid-framing. We order long-lead items the week the contract is signed.
Pricing for Home Additions & ADU in Upland, CA
Here’s what we’re seeing in Upland right now, line item by line item:
| Project Type | Typical Range in Upland |
|---|---|
| Home Addition | $45,000-$130,000 |
| ADU Construction | $90,000-$220,000 |
| Second Story Addition | $45,000-$130,000 |
| Garage Conversion | $30,000-$80,000 |
What moves the number in Upland? The fault zone, first. A parcel inside the Alquist-Priolo study zone in 91784 adds a geotech report, more review time, and possibly engineered foundation work. The slope, second. A hillside lot off Mountain Avenue north of the 210 needs grading plans, retaining structures, and drainage engineering that a flat 91786 lot never requires. And finishes, third. If you’re specifying custom millwork, architectural glass, and designer plumbing fixtures, the material line alone can be $40,000-$80,000 before labor. We write every allowance on paper, every scope item on paper, and every change on paper before it happens. Call (877) 610-1318 to schedule a free estimate, and we’ll give you a written number you can hold.
On a 1970s custom hillside home off Mountain Avenue near the San Antonio Heights border, our crew handled a second-story addition where the owner’s original scope of work assumed standard slab-on-grade loads. We discovered the parcel fell within the Alquist-Priolo study zone, triggering a fault-rupture study that added three weeks and shifted the subfloor framing to an engineered load-bearing system with a retained hillside wall. We coordinated the geotech, architect, and the city’s inspection sign-off before any vertical framing began. That’s what we mean when we say we handle Upland properly: we find the site condition early and put it in writing.
We Also Serve Cities Near Upland
While this page is focused on Upland, our crews regularly work in Claremont, Montclair, Rancho Cucamonga, and Ontario. Each city has its own building code quirks and its own soil conditions, but the approach is the same: written scope, permits pulled, change orders before any scope change, and Tom’s name on the work.
Serving Upland, CA - Our Local Coverage Area
We’re based in the Upland area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - Home Additions & ADU in Upland
The quickest way is to check Upland’s official general plan maps and the California Geological Survey’s Alquist-Priolo fault zone maps for the Cucamonga Fault. If your parcel is in 91784 near the mountain front, north of the 210, there’s a meaningful chance it falls within or adjacent to the study zone. We pull this map for every Upland project before design begins, because the answer changes the foundation design, the permit timeline, and the budget. Call (877) 610-1318 and we’ll check your parcel during the free estimate.
A second-story addition on a hillside lot in 91784 typically runs 8-14 months from design to final inspection. The fault-rupture study alone adds 3-6 weeks if the parcel triggers it. Custom millwork and architectural glass add 10-16 weeks for fabrication. The labor is not what drives the calendar; the engineered plans, the geotech reviews, and the long-lead materials do. We sequence the orders early so the schedule doesn’t stall mid-framing.
Because 91784 sits on sloped alluvial-fan terrain at the base of the San Gabriel Mountains, where stormwater flows fast, soils are less stable, and the city’s hillside grading ordinance requires engineering for any structure that changes drainage or cuts into a slope. 91786 is flat former citrus-belt land, and the building department does not apply the same hillside provisions. It’s a geography question, not a paperwork question.
Usually yes, if the garage is in 91786 on a flat lot outside the Alquist-Priolo study zone. The existing slab is typically accepted as the foundation, and the work is treated as a remodel rather than ground-up construction. But if the garage is in 91784 near the mountain front, or if the project adds a new foundation element of any kind, the fault-zone question comes back. We’ll tell you which path applies to your parcel before you spend money on design.
We write the scope and every allowance on paper at contract signing, and we convert allowances to firm line items before placing the order with the supplier. If a designer changes a tile spec, a plumbing fixture, or a window package, you receive a written change order with the new price before we order anything. No verbal allowance. No surprise invoice at the end. That’s how a $100,000 addition stays a $100,000 addition in Upland.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Upland and the surrounding Inland Empire since 1998.