Licensed & Insured • ROC #318269
The Custom Builder You've Trusted for Over 17+ Years
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(602) 361-2310ADUs, additions, guest houses, and more — designed, permitted, and built by one trusted team.
What We Build
Our Services
From backyard ADUs to full home additions, we handle design, permitting, and construction — so you get one team, one vision, and zero headaches.
ADU Construction
Custom detached or attached ADUs designed to match your home. Perfect for rental income, family, or a private retreat.
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Home Additions
Expand your living space with bedrooms, bathrooms, second stories, or full wing additions — built to blend seamlessly.
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Guest Houses & Casitas
Standalone living spaces with full kitchens, bathrooms, and custom finishes — ideal for guests or multigenerational living.
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Pool Houses
Enjoy your outdoor space year-round with a custom pool house built for Arizona's climate and your lifestyle.
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Garages & RV Garages
Detached garages, oversized RV garages, and garage conversions — designed for your vehicles and storage needs.
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Mother-in-Law Suites
Private, accessible suites designed for comfort and independence — keep family close while giving everyone their space.
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Leave the Building to the Pros
We handle the hard parts so you can focus on the exciting ones.
Design & Build Under One Roof
We handle everything from architectural design and 3D renderings to full construction — one team, one point of contact.
Zoning & Permitting Experts
We know Maricopa County codes inside and out. Every design we create is buildable — no rejected permits, no wasted time.
Transparent Pricing
Clear, detailed estimates from day one. No hidden fees, no change-order surprises — just honest numbers you can plan around.
Owner On-Site Daily
Mark Kelso personally oversees every project. You get direct access to the owner from start to finish.
Our Work
Recent Projects
Custom homes and additions built across the Phoenix metropolitan area.
About Kelso Custom Builders
Here to Answer Any Questions
Owner Mark Kelso began his career in the trades at just seventeen years old as an electrician. After decades of hands-on experience, he and his wife Jamie founded Kelso Custom Builders to bring a personal, quality-focused approach to every project.
Today, with over 17 years in business, we serve homeowners across Phoenix, Scottsdale, Cave Creek, Paradise Valley, and the entire Maricopa County area. Every project gets Mark's personal attention — from the first design meeting to the final walkthrough.
Client Testimonials
What Our Clients Say
"Great communication, great guy, gets job done in very very timely fashion."
"Very responsive and thorough. Patiently educates homeowner. Creative suggestions."
"Great guy, very easy to work with and understands what you are trying to accomplish."
Where We Work
Serving the Greater Phoenix Area
Get Started
Begin Your Custom Build Today
Tell us about your project and we'll provide a free, no-obligation estimate. We typically respond within one business day.