Types of Home Additions
Guide
The main types of home additions compared: room, kitchen bump-out, second story, sunroom, garage, and ADU — cost, scope, and fit.
Room additions.
A single new room — bedroom, living space, or office — is the most straightforward addition. It usually needs a foundation, a roof tie-in, and services extended from the existing house. Cost depends mainly on size, finish, and whether plumbing is involved.
Kitchen bump-outs.
A small extension to enlarge a kitchen can change how the whole ground floor works. Plumbing, wiring, and cabinetry make it more complex per square foot than a plain room, even though the area added is often small.
Second stories.
Building up adds a full floor without taking more land. It needs careful structural work, a new roof, and extended heating, plumbing, and wiring. It suits homes on small lots where going outward is not practical.
Sunrooms.
A glass-heavy room suits light and views, but heating, cooling, and glazing specification matter more than in a conventional room. A three-season room and a four-season room are different projects with different costs.
Garages and ADUs.
An attached garage adds storage and workspace at a lower per-square-foot cost than living space, because the finish is simpler. An accessory dwelling unit adds a self-contained living space with its own kitchen and bathroom, and is priced more like a small home than a single room.
Related
Home addition cost calculator · Addition cost hub
- Home Addition Checklist
- Building Permit Guide
- Types of Home Additions
- Home Addition Financing
- Choose a Contractor
- Home Addition Timeline
Planning estimate only, based on 2026 cost data. It is not a quote. Get itemised bids from licensed local contractors before building, and set aside a 10–20% contingency for permits, design fees, and site surprises.