Cost guide
Mudroom Addition Cost in 2026
A mudroom is a small bump-out at an entry, so the fixed costs of an addition (design, permits, roof tie-in) make up much of the price. Size and finish decide the rest.
Step 1 of 4
Your addition
Size and type.
Labor costs differ a lot by state. This adjusts every line.
New finished floor area, not counting the existing house.
Type of addition
Foundation
Estimated addition cost
$113,900
$73,000 – $154,800
The calculator above starts as a 300 sq ft room. Open it set to a 100 sq ft bump-out to price a mudroom.
Mudroom addition cost by size
| Scenario | Estimated range | Per sq ft |
|---|---|---|
| Compact mudroom (80 sq ft)Bump-out with heating and cooling, standard finishes | $26,000 – $62,800 | $325–$785 |
| Standard mudroom (100 sq ft)Bump-out with heating and cooling, standard finishes | $29,700 – $69,000 | $297–$690 |
| Large mudroom or laundry entry (150 sq ft)Room for lockers, a bench and a laundry sink | $39,100 – $84,600 | $261–$564 |
| Basic mudroom, unconditioned (100 sq ft)Basic finishes, no heating or cooling extended | $24,100 – $56,500 | $241–$565 |
Estimates at national-average pricing, calculated with our own pricing engine and reviewed September 2026. Change the inputs in the calculator to price your exact project.
A standard 100 sq ft mudroom bump-out costs about $29,700–$69,000. Skipping the heating and cooling and choosing basic finishes brings the low end down.
What drives mudroom addition cost
- Type matters most: a second story costs more per sq ft than a ground-floor room, but needs no new foundation.
- Bathrooms and kitchens are plumbing-heavy and can add $30k–$70k.
- Architect fees, permits and utility tie-ins are often missing from rough quotes.
- Additions carry more unknowns, so this estimate includes a larger contingency.
Ways to keep a mudroom affordable
- Enclose an existing porch or breezeway instead of building new. The roof and slab may already be there.
- Skip the heating and cooling if you only need a place for coats and boots.
- Use durable, simple finishes: sealed concrete or tile, painted trim and built-in hooks.
- Ask a contractor whether a bump-out can cantilever without a full foundation.
Frequently asked questions
How much does a mudroom addition cost?
A 100 sq ft mudroom bump-out costs about $29,700–$69,000 nationally, including design, permits and a contingency. Your state and finishes change the number.
Why is a mudroom expensive for its size?
A small addition still needs design, permits, a roof connection and utility work. Those costs are close to fixed, so on a very small room they are spread over few square feet.
Can I turn a porch into a mudroom?
Often yes, and it usually costs less than a new addition because the roof and floor may already exist. You still need insulation, windows or doors, wiring and a permit.
Do I need a permit for a mudroom?
Almost always. Any new enclosed space attached to a house needs a permit and inspections.