Cost to Attic Conversion in St. Louis, MO

$22,000–$66,000 in St. Louis

12% below the national average · 0.88x cost multiplier

In St. Louis, a attic conversion runs $22,000 to $66,000 on average — about 12% below what homeowners pay nationwide. The Midwest market's labor costs account for most of the gap, with material pricing and local permitting fees adding to the spread. Use the cost table below to compare budget, mid-range, and premium options side by side.

Cost Breakdown in St. Louis

Line Item	Low	Mid	High
Materials	$7,040	$13,200	$26,400
Labor	$13,200	$26,400	$52,800
Permits	$1,320	$2,200	$3,520
Design	$440	$2,200	$5,280
Total	$22,000-12% vs. national avg	$44,000-12% vs. national avg	$88,000-12% vs. national avg

Budget

Basic attic conversion to a home office or bonus room where structural work is minimal, existing floor joists can support the load, and HVAC can be extended. Insulation, drywall, basic flooring, staircase, and one window. No bathroom.

Mid-Range

Full attic bedroom or bonus room conversion with proper egress window, new staircase, mini-split HVAC, hardwood or LVP flooring, insulation upgrade, bathroom rough-in (half bath), and quality finishes matching the rest of the home.

Premium

Master suite or full attic apartment with structural reinforcement, dormers for added headroom, full bathroom, kitchenette, dedicated HVAC system, skylights, built-ins, and premium finishes. Structural engineer required.

Material Options

Material prices below are national averages; availability in St. Louis may shift costs slightly.

Material	Cost/Unit	Pros	Cons	Best For
Bonus Room / Home Office (No Bathroom)	$50-$80/sq ft	Lower cost, simpler permits, faster completion	Limited appeal as a bedroom without bathroom, no plumbing for future upgrade	Home offices, playrooms, hobby spaces, home theatersLower cost, simpler permits, faster completion
Bedroom with Half Bath	$75-$120/sq ft	Classifies as a legal bedroom, adds significant home value	Plumbing complexity adds cost and timeline	Expanding bedroom count, guest suitesClassifies as a legal bedroom, adds significant home value
Full Master Suite with Bathroom	$100-$175/sq ft	Maximum value addition, luxury private retreat	Highest cost and structural complexity; dormers often required for headroom	Homes where adding a primary suite increases value mostMaximum value addition, luxury private retreat
Shed Dormer Addition	$10,000-$20,000 flat (not per sq ft)	Dramatically increases usable floor area and natural light, often makes the difference in whether conversion is viable	Significant structural project, changes exterior roof appearance	Attics with insufficient headroom for legal habitable spaceDramatically increases usable floor area and natural light, often makes the difference in whether conversion is viable
Skylight Installation (Instead of Dormers)	$1,500-$3,500 per skylight	Lower cost than dormers, adds light without changing the roofline	Does not add headroom - only improves light and ventilation	Attics with adequate headroom needing light; budget alternative to dormersLower cost than dormers, adds light without changing the roofline

Other Projects in St. Louis

Full Kitchen Remodel

Basement Finishing

Roof Replacement (Asphalt Shingles)

Back to national average for Attic Conversion

St. Louis Estimate

Typical Range

$22,000–$66,000

vs. National Average

12% below national

Cost Multiplier

0.88x

Estimates apply St. Louis's 0.88x regional cost multiplier to national averages. Actual bids vary by contractor, project scope, and timing.

See national average costs →