An accessory dwelling unit — a small, fully independent home on the same lot as your house — is one of the most flexible things you can build. A place for aging parents to live close by. A home office that isn't a spare bedroom. A rental that helps pay the mortgage. A starter home for an adult child.

Wes-Tec Builders designs and builds ADUs across the Denver metro, and we've been building in this market since 1986. We're a family company, BBB A+ accredited with zero complaints filed — a record we believe no other Colorado home improvement company can match.

Three ways to build an ADU

Detached ADU. A brand-new small home in the backyard — a cottage, a studio, a one- or two-bedroom unit. Detached ADUs offer the most privacy and the most design freedom, and they're the most common choice when the lot has room.

Garage conversion. Your existing garage becomes living space: insulation, HVAC, plumbing, a kitchen and bath, and a real front door. Conversions cost substantially less than building new because the foundation, walls, and roof already exist — but you give up the garage, and the conversion still needs full residential permits.

Above-garage ADU. A living unit built over a new or existing garage. It's a smart fit for lots where yard space is tight: you keep the garage and gain a home above it. Above-garage ADUs involve more structural work than a conversion, since the garage has to carry a second floor.

Can I build an ADU on my lot?

ADU rules vary by city and by zone — setbacks, height limits, size limits, parking, and owner-occupancy rules are all local, and they change. Some Front Range cities have loosened their ADU rules significantly in recent years; others are stricter. That's why we start every ADU project with a free feasibility check: we look at your lot, your zoning, and your utilities, and tell you what's actually possible before you spend anything on design.

We do not quote a one-size-fits-all size limit, because there isn't one — the rules for your lot depend on your city and your zone.

What an ADU costs — and why

ADUs are full homes in miniature: kitchen, bathroom, HVAC, electrical, plumbing, insulation, and finishes — plus permits, engineering, and utility connections. As approximate Denver-market ranges (not Wes-Tec quotes):

What moves your number most is utilities: running power, gas, water, and sewer to a detached or above-garage unit, including trenching and panel upgrades, is one of the biggest swing factors. Site conditions matter too — slope, soil, drainage, alley access, and distance from your home's utilities all move the price. Finish level matters as well: a basic studio and a fully appointed one-bedroom are different projects.

Final pricing comes from a free in-home estimate and feasibility check — we'll give you your exact number, not a guess.

Our process — design, engineering, and permits handled in-house

1. Free feasibility check and estimate — we confirm what your city and zone allow, look at your lot and utilities, and give you a real number.
2. Design and engineering — floor plan, 3D model, structural engineering stamp, and permit drawings, all coordinated by us.
3. Permits and construction — we pull permits, coordinate utility work and inspections, and handle HOA approvals.

Full ADUs typically run 4–8 months of construction, with 2–4 months of design, engineering, and permitting before that. Garage conversions run 2–4 months. Utility work and inspections are usually the long poles.

FAQs

Do I need a permit to build an ADU?

Yes — ADUs need full residential permits plus zoning review, and rentals may need to meet additional local requirements. We handle all of it.

Is it cheaper to convert my garage or build a detached ADU?

Converting is usually $100,000+ cheaper than building detached new, because you already have the foundation, walls, and roof. But you lose the garage, and the conversion still needs insulation, HVAC, plumbing, and permits.

Can I rent out my ADU?

In many Denver-metro cities, yes — but rental and landlord-tenant rules vary by city. We flag the local rules during the feasibility check so there are no surprises.

Will an ADU increase my property taxes?

Added living space gets assessed, so expect a modest increase. If the ADU generates rental income, the math usually still works strongly in your favor.

Thinking about an ADU? Start with a free feasibility check. Call Wes-Tec Builders at 303-improve or visit westec-builders.com. Forty years family-run, BBB A+ with zero complaints filed — a record we believe no other Colorado home improvement company can match.

Call Now: 303-improve