A garage can be a lot more than a place to park: a mudroom, a workshop, a gym, an office, a bonus room overhead, or full living space. Dom’s Workshop, Inc is a residential general contractor based in Plaistow, NH, and we help homeowners across Rockingham County plan garage projects that suit their house and their budget. This guide covers what drives the cost of the most common garage projects.
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Common garage projects
- Finished garage. Insulation, drywall, lighting, outlets, and an upgraded floor, still used for parking.
- Storage and organization. Wall systems, cabinets, overhead racks, and a workbench.
- Mudroom connection. A finished entry between the garage and the house with a bench, cubbies, and durable flooring.
- Workshop or gym. Dedicated circuits, heat, lighting, and the right flooring.
- Garage conversion. Turning part or all of the garage into living space: a family room, a bedroom, an office, or an in-law suite.
- Room above the garage. Adding or finishing a bonus room over the bays.
- New garage. Attached or detached, with or without space above.
See garage remodeling for what we do.
What drives garage remodel costs
The slab
Garage floors are often sloped, cracked, or below the house’s floor level. A conversion may need a raised, insulated floor. A workshop may need crack repair and a durable coating.
Insulation and air sealing
Most garages aren’t insulated. Walls, the ceiling, and sometimes the slab edge need it before the space can be comfortable, and converting to living space requires meeting energy code.
Heat and ventilation
A garage often isn’t served by the house’s heating system. Options include extending the existing system or adding a separate heat source. Workshops and gyms need fresh air.
The garage door opening
In a conversion, the big opening is usually framed in with a wall, windows, and siding to match the house. That’s a significant part of the scope.
Electrical
More outlets, dedicated circuits for tools or a car charger, and better lighting. Older homes may need a panel upgrade.
Fire separation
Code requires a fire-rated separation between an attached garage and the living space. Any project that changes that wall or ceiling has to maintain it.
Plumbing
A utility sink, a bathroom, or a kitchenette in a conversion adds plumbing, and in a slab that can mean cutting concrete.
Building a new garage: what changes the cost
- Attached vs. detached. An attached garage needs a roof tie-in, fire separation, and often a mudroom link. A detached garage needs its own foundation and sometimes a longer driveway.
- Foundation. A frost-protected foundation is required in New Hampshire winters. Ledge or poor soil adds excavation.
- Size and bays. One, two, or three bays, plus extra depth for a workshop or storage.
- Space above. Storage trusses, an attic, or a full bonus room with stairs, insulation, and heat.
- Doors and finishes. Insulated garage doors, windows, and siding and roofing that match the house.
- Site work. Grading, drainage away from the slab, and any driveway changes.
Rockingham County considerations
- Septic. Converting a garage to a bedroom or in-law suite usually requires a septic capacity review.
- Setbacks. New garages, and second stories over existing garages, must meet zoning setbacks and height limits.
- Winter. If you convert the garage, you lose covered parking. Many homeowners keep one bay or plan a new garage.
- Permits. Conversions, new garages, and electrical or plumbing work need permits. We can take care of permits for you.
Ways to manage a garage budget
- Finish the garage but keep it a garage. That’s much less work than a full conversion.
- Add a mudroom in part of one bay instead of converting the whole space.
- Plan the room above when you build a new garage, even if you finish it later.
- Use durable, simple finishes where the space will see hard use.
Garage planning checklist
- How will you use the space, now and in five years?
- Do you need to keep parking?
- Is heat needed?
- Will there be a bedroom or bathroom (septic review)?
- What electrical loads are planned (tools, a car charger)?
For related budgets, see the room addition cost guide and the home remodel cost guide.
Garage cost FAQ
Is converting a garage cheaper than an addition?
Often, because the foundation, walls, and roof already exist. But insulation, the slab, heat, and framing in the door opening still add up.
Do I need a permit to convert my garage?
Yes, in most cases. We can take care of permits for you.
Can I put a bedroom over my garage?
Often, if the structure and setbacks allow. On septic, a new bedroom needs a capacity check.
Will I lose value by converting a garage?
It depends on the neighborhood and what buyers expect. Many owners keep at least one bay.
How do I get a real number?
Request an estimate for a site visit and a written scope.
Plan your garage project
Dom’s Workshop serves towns across Rockingham County. See Areas We Serve.
Dom’s Workshop, Inc, based in Plaistow, NH, serving Rockingham County, NH · (978) 775-8642 · Dom@doms-workshop.com