Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
Before
After
Before
After
Before
AfterFast, Reliable Home Additions & ADU Across Folsom
Home additions and ADU construction in Folsom typically run $45,000-$130,000 for room additions and $90,000-$220,000 for detached ADUs, with garage conversions landing between $30,000-$80,000. Most of our Folsom jobs are in the 95630 and 95763 ZIP codes, and we know exactly what the HOA boards, building inspectors, and WUI fire codes require before the first shovel hits dirt. Call (877) 610-1318 and we’ll walk the property with you, look at what’s there, and give you a written scope before you commit to anything.
We’re Barrett & Sons Construction, and Tom Barrett’s name, address, and license number are published for anyone to look up. That’s the point. You’re not getting a call center. You’re getting us.
Why Barrett & Sons Construction Is Folsom’s Preferred Home Additions & ADU Company
We’ve built enough Home Additions & ADU projects in Folsom to know that this city is different from the flat valley towns around it. Empire Ranch red-tile roofs have strict architectural review. Folsom Ranch lots sit on granite that laughs at a standard auger. American River Canyon hillside parcels trigger California’s full Wildland-Urban Interface building code, which changes everything from your siding to your soffit vents. We handle all of it without making you the middleman.
Our reviews from Folsom customers lean on the same things: the crew showed up when they said they would, the change order came in writing before the price moved, and Tom answered the phone when there was a question. We don’t paper over a rock strike or a failed inspection and surprise you later. The permit inspector works for you, not for me, and that’s exactly why we want him on every eligible job.
Crews serving Folsom are coordinated from our Sacramento office, but the guys on your lot carry the Barrett & Sons name, are background-checked, and wear uniforms. Tom’s sons run crews. It’s not a franchise dispatching strangers.
Our Home Additions & ADU Services in Folsom
ADU Design & Permitting
Folsom ADU projects live or die at the permit counter. Between the city’s ADU ordinance, HOA architectural review in Folsom Ranch and Empire Ranch, and WUI fire requirements in the eastern hillside zones, there are a dozen ways to get a plan kicked back. We handle the design, the submittals, the revisions, and the inspections. You sign one scope, and we pull every permit on the job before work starts.
New Detached ADU
A detached ADU in Folsom runs $90,000-$220,000 depending on size, site access, and whether the lot sits in a granite-heavy foothill section. In the 95763 ZIP, many Folsom Ranch lots have hard rock close to the surface, which can add pneumatic breaking to the site prep line item. We write that into the scope upfront. No surprises. If your lot is in the WUI overlay, you’ll also need ember-resistant vents and ignition-resistant siding, and we spec those materials from the first drawing.
Garage Conversion ADU
Converting an attached garage in Folsom typically runs $30,000-$80,000. The 95630 ZIP is full of 1990s and 2000s tract homes on slab foundations, which usually convert cleanly. The bigger question is the builder warranty. Cutting into the stucco wall to tie in a new entrance can void the original structural warranty on that connection point, and you need to know that before the saw comes out. We’ll tell you exactly which parts of the warranty survive and which don’t.
Junior ADU & Interior Conversion
A Junior ADU inside your existing Folsom house is the fastest path to a rental unit or an in-law suite, and in many cases it doesn’t require a separate utility connection. The catch is that JADUs have a 500-square-foot cap and normally need independent exterior access. Older Empire Ranch and Broadstone floor plans don’t always have a good spot for that door, but we’ll tell you honestly if it works. If it doesn’t, we’ll show you the next best option.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Folsom
For windows and doors on Folsom ADUs and second-story additions, we install Simonton, Ply Gem, and PGT products. These aren’t mystery brands off a van. You can look up the specs, read the NFRC ratings, and check the WUI compliance sheets yourself. For Folsom projects in the fire-hardening zones, Simonton and PGT both make ember-resistant, impact-rated window assemblies that pass local inspection without a fight.
Common Home Additions & ADU Problems We See in Folsom Homes
- HOA stop orders mid-project. In master-planned communities like Empire Ranch and Folsom Ranch, the HOA’s architectural committee can stop an ADU at rough-in if the roof pitch, exterior color, or window style doesn’t match the design guidelines. We pull the HOA review paperwork before we ever file for a building permit.
- Granite bedrock under the footings. Folsom’s foothill terrain sits on the same granite that built the State Capitol. Excavation for a second-story addition pier or an ADU foundation in the hillside sections regularly hits rock that needs pneumatic breakers. We write the contingency into the change order structure so you see the number before it hits the invoice.
- Builder warranties voided by cut-ins. When you tie a room addition into a 1990s stucco tract home, the cut into the exterior wall often voids your original builder structural warranty on that wall and any connected roofline. We’ll show you exactly which warranty sections survive and which don’t, in writing, before you sign.
- Framing lumber warped by Folsom heat. Folsom summers regularly exceed 105°F with single-digit humidity. Green or improperly stored framing lumber can dry so fast it twists before the sheathing goes on. Our crews schedule framing deliveries tightly and store material out of direct sun, which is the difference between passing inspection on the first visit and tearing out warped studs.
Pricing for Home Additions & ADU in Folsom, CA
We’ll give you real Folsom numbers, not a “well, it depends.” Here’s what you’re looking at.
| Project Type | Typical Folsom Price Range |
|---|---|
| New Detached ADU | $90,000-$220,000 |
| Home Addition | $45,000-$130,000 |
| Garage Conversion ADU | $30,000-$80,000 |
What moves the number: lot access (hillside Folsom parcels cost more to stage), granite encounters during excavation, WUI material upgrades, and HOA approval time. We write every allowance, every change order, and every permit fee on paper before work proceeds. The allowance that isn’t on paper is a surprise waiting for a date. Call (877) 610-1318 and we’ll put a written estimate in your hand. Free, and worth the phone call.
We Also Serve Cities Near Folsom
Our crews work Folsom every week, and we regularly take on projects in Orangevale, Granite Bay, El Dorado Hills, and Fair Oaks. If you’re just outside the Folsom city line, the same team, the same written pricing, and the same 90-Day Done Right Promise apply. Call (877) 610-1318 and ask for Tom.
Serving Folsom, CA - Our Local Coverage Area
We’re based in the Folsom 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 Folsom
Yes. Both Folsom Ranch and Empire Ranch have active architectural review committees that must approve your ADU’s roof pitch, exterior color, window style, and setback before the city will even look at your permit application. Skipping this step is the single most common reason Folsom ADU projects stall at rough-in. We handle the HOA submittal as part of our permitting scope, so you don’t end up re-drawing the plans mid-project. Call (877) 610-1318 and we’ll tell you exactly what your specific HOA requires.
If your lot is in the foothill sections of Folsom where granite sits close to the surface, you may need pneumatic breaking or rock hammers to get your new foundation piers down to code depth. That can add $3,000-$8,000 to the excavation line item depending on how much rock we hit. We’ll flag this risk before we quote, and if we hit rock mid-dig, you’ll get a written change order before any price moves. Call (877) 610-1318 to schedule a site walk and we’ll check the soil map for your parcel.
It can. When you cut into the stucco or framing of a 1990s-2000s tract home to tie in the new ADU entrance, the original builder structural warranty on that connection point is typically voided. Non-structural components of the warranty usually survive. We’ll review your original warranty documents and give you a written list of what’s covered and what isn’t before work starts. Call (877) 610-1318 for an honest read on your specific home.
In Folsom’s Wildland-Urban Interface overlay, a detached ADU needs Class A roofing, ember-resistant vents, ignition-resistant siding (like HardiePlank), and double-paned windows with tight mesh screens. The exact spec depends on your parcel’s fire hazard severity zone, which we check on Cal Fire’s map before we draw anything. We price these materials into the original quote, not as a surprise add-on. Call (877) 610-1318 and we’ll confirm your parcel’s WUI status for free.
Yes, in most cases. A Junior ADU inside your existing Folsom home can share the main house’s water, sewer, and electrical service, which saves you $10,000-$20,000 compared to a detached ADU that needs new utility drops. The JADU just needs its own exterior access and a small kitchenette, and it’s capped at 500 square feet. We’ll tell you if your floor plan works. Call (877) 610-1318 and we’ll take a look.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Folsom since 1998.