A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateFast, Reliable Home Addition Contractor Across Monrovia
Home additions in Monrovia typically run $180 to $420 per square foot depending on the scope, with a full second-story addition landing between $220,000 and $450,000 and a garage conversion or bump-out starting closer to $85,000. Those are the honest numbers, and we put them in writing before any work starts. If you live near Monrovia High, over on North Mayflower Avenue, or up in the foothill neighborhoods above Foothill Boulevard, you’ve probably watched a neighbor wrestle with a cramped kitchen or a bedroom that stopped working the moment a second kid arrived.
Benson ADU Builders, led by Troy Eastman, handles the whole addition from as-built survey to final inspection. You call (903) 568-7222, you get a live person, and you get a written price before a single shovel turns. No phone tag, no disappearing act between estimate and demo day.
Why Benson ADU Builders Is Monrovia’s Preferred Home Addition Contractor Company
Most of the additions we scope in Monrovia involve pre-1940s bungalows on narrow lots, often with detached garages sitting near the rear alley. That geometry changes everything about how an addition gets designed. A house on a 5,000-square-foot lot with a non-conforming garage can’t always add square footage the way a newer tract home can, and we walk homeowners through that reality in the first conversation, not after the plans come back from plan check.
We’re part of the Relay Home Co. family, founded in 2006, and every Monrovia project carries The Relay Visibility Guarantee: a written price before work starts, a 365-Day Done Right Promise, and a free second visit if any covered repair fails within that year. All of our technicians are background-checked and arrive in uniform, so when someone walks up your driveway on a morning in the 91016 area, you know exactly who it is and exactly what they’re there to do.
Our Home Addition Contractor team has walked plenty of Monrovia lots from the Old Town blocks near Myrtle Avenue to the hillside streets above Norumbega Drive. We know which sides of town hit design review, which lots fight setback requirements, and which older homes need structural upgrades before a second floor goes on. That local knowledge gets priced into the written estimate, not billed as a surprise later.
Second Story Addition Contractor in Monrovia
A Second Story Addition Contractor in Monrovia is dealing with something most other cities in the San Gabriel Valley don’t see as often: 1920s and 1930s wood-frame bungalows that were never engineered for a second floor. Adding a second story here means checking the foundation and the existing studs before the first framing nail goes in. On a typical Monrovia bungalow, a full second-story addition with a new primary suite and a second bath runs $240,000 to $420,000, and plan check alone can take four to eight weeks depending on whether the property sits in a historic-adjacent district.
What the structural work actually involves
Existing footings under a 1930s home were poured for a single story. When you add a second floor, those footings carry more load, so the plans either reinforce them or add a structural steel beam to carry the upper level. The same applies to the ceiling joists on the main floor – they become floor joists for the new level, and they almost always need to be upsized.
Why design review can add time here
Parts of Monrovia near Old Town and the historic-adjacent blocks can trigger a design review step for visible additions. The city wants new work to match the character of the original house, and that means exterior material choices matter before plans get submitted, not after a neighbor complains. We spec compatible materials from the first drawing so plan check doesn’t send the project back for rework.
Garage Addition Contractors in Monrovia
Garage Addition Contractors in Monrovia spend a lot of time on detached garages sitting at the back of narrow lots, many of them non-conforming to current setback rules. Converting that garage into livable square footage often makes more sense than building new footprint, but only if the city will allow it. A garage conversion to a studio ADU or a family room in Monrovia typically lands between $85,000 and $180,000, and the permit path depends on whether the existing structure can be brought up to current code.
Setback realities on narrow Monrovia lots
Lots in the 91016 and 91017 areas often measure 50 feet wide or less, which puts the rear garage close to the property line. When a garage is non-conforming, Monrovia may allow the conversion to proceed, but you’ll need an as-built survey to prove the existing conditions before plans go in. We order that survey first, because discovering the non-conforming condition halfway through design is how budgets and timelines quietly blow up.
Fire access and sewer lateral requirements
Rear additions and garage conversions on narrow lots trigger fire department review for vehicle access, and many older Monrovia homes need a sewer lateral replacement or repair before the addition can pass inspection. We identify these items in the written scope so you’re never hit with a surprise line item after the permit is pulled.
Trusted Brands We Service in Monrovia
Benson ADU Builders builds with prefab systems from Abodu, Cover, and Dvele, which gives Monrovia homeowners a faster path to a permitted addition than a traditional site-built build from scratch. These are brands you can research independently – Abodu and Cover are both known for their prefab ADU and addition panels, and Dvele builds high-performance prefab homes with a focus on long-term durability. For cladding and exterior finishes on visible additions, we spec James Hardie siding, which holds up better to Monrovia’s hot foothill summers than older wood siding and matches the look of existing stucco closely enough to pass design review. We stock common replacement parts locally for the brands we install, so warranty work in Monrovia doesn’t wait on a parts shipment from out of state.
Common Home Addition Contractor Problems We See in Monrovia Homes
- Non-conforming garages discovered after design starts. Many Monrovia garages built before current setback rules exist are too close to the property line. Skipping the as-built survey means finding this out at plan check, which forces a redesign and adds weeks.
- Incompatible exterior materials on historic-adjacent blocks. Visible additions near Old Town can trigger design review if the new siding or roofline doesn’t match the original character of the house. Swapping materials mid-review is expensive and preventable.
- Fire-access and sewer lateral surprises on rear additions. Narrow Monrovia lots often fail fire department vehicle-access review the first time through, and old sewer laterals under the alley may need replacement before final sign-off. Both should be scoped before permits are pulled.
- Foundations under-built for a second story. Pre-1940s bungalows poured for one story can’t always carry a second without structural reinforcement. A homeowner who skips the structural review ends up paying for beam work mid-framing.
Pricing for Home Addition Contractor in Monrovia, CA
Here’s the honest picture for Monrovia’s market. A bump-out addition, like widening a kitchen or expanding a primary bedroom, runs $95,000 to $190,000. A full second-story addition lands between $220,000 and $450,000 depending on structural upgrades, bathroom count, and whether design review applies. A garage conversion to living space or an ADU starts around $85,000 and tops out near $180,000. What moves the number: the condition of the existing foundation, whether the property sits in a historic-adjacent zone, sewer lateral condition, and the cost of matching existing exterior materials on a visible addition. Call (903) 568-7222 for a free, written estimate. You’ll have a real number before we ask for a deposit.
We Also Serve Cities Near Monrovia
Our crew serves Home Addition Contractor in Monrovia and the surrounding San Gabriel Valley cities, including Arcadia, Duarte, Sierra Madre, and Baldwin Park. If your property sits on the edge of Monrovia, one of those borders may apply to your permit jurisdiction, and we’ll sort that out during the scoping call.
Serving Monrovia, CA - Our Local Coverage Area
We’re based in the Monrovia 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 About Home Addition Contractor in Monrovia
Yes. A second-story addition in Monrovia requires a separate structural permit, and it may also require design review if the property is in a historic-adjacent zone, plus fire department approval for access on narrow lots. We handle every permit in the written scope, and we order the as-built survey before plans are submitted. Call (903) 568-7222 for a free scoping conversation.
In most cases, yes, provided the existing garage can meet current code or be brought up to it. Monrovia permits garage conversions to ADUs as long as setbacks, fire access, and sewer lateral requirements are addressed. We scope the conversion fully before you commit, and we put the price in writing. Call (903) 568-7222 to get an exact quote for your garage.
Expect six to nine months for a typical Monrovia addition. Plan check alone runs four to eight weeks depending on design review, and construction on a second-story addition usually takes four to six months. Garage conversions are faster, often three to four months from permit to final inspection. We’ll give you a calendar with the written estimate.
Unforeseen structural conditions are the biggest one. If the foundation turns out to be under-built, that adds scope and cost. Sewer lateral issues and fire-access upgrades are the other common surprises on narrow lots. The written estimate addresses the likely ones up front, and we never bill for scope changes without a written change order you approve first. Call (903) 568-7222 to talk through your specific property.
Yes. We’re a full-scope Home Addition Contractor for Monrovia, and we handle second-story additions, garage conversions, bump-outs, and ADUs. Troy Eastman and the team manage the entire project from survey through final inspection, and every job carries the 365-Day Done Right Promise. Call (903) 568-7222 to schedule your free estimate.
Written by Troy Eastman, Owner at Benson ADU Builders, serving Monrovia home addition and ADU projects since 2006.
