How Much Does It Cost to Finish a Basement in Longmont, CO?

By Vern Marchand · Basements.com · Updated June 2026 · 8 min read

If you're a homeowner in Longmont, Erie, Boulder, or Firestone considering finishing your basement, the first question is always: how much is this going to cost?

After finishing hundreds of basements across Northern Colorado over 25+ years, here's what we see in 2026.

Average Basement Finishing Cost in Longmont, CO (2026)

Basement finishing in Northern Colorado typically ranges from $28,000 to $75,000+ for a full finish, depending on size, features, and finish quality.

• Basic finish (no bathroom): $28,000 – $40,000
• Mid-range finish (with one bathroom): $40,000 – $60,000
• High-end / custom finish: $60,000 – $100,000+

On a per-square-foot basis, expect $40–$75/sq ft for Longmont and Boulder County projects. Weld County (Erie, Firestone, Frederick) tends to run slightly less.

What's Included in a Full Basement Finish?

A complete basement finish includes framing all walls, insulation, electrical wiring and panel work, recessed lighting, HVAC extension, drywall, painting, flooring, trim, and all permits and inspections. Here's a rough cost breakdown:

• Framing: $3,000–$7,000
• Electrical: $4,000–$9,000
• HVAC extension: $2,000–$5,000
• Drywall: $4,000–$8,000
• Flooring: $4,000–$10,000
• Painting: $2,000–$4,000
• Trim & doors: $2,000–$5,000
• Permits & inspections: $800–$2,000

Add-Ons That Increase Cost

Bathroom Addition: +$8,000–$18,000

Adding a full bathroom requires rough plumbing, a sewage ejector pump (in most basements), tile, fixtures, and a vanity. It's the single biggest add to a basement project budget — and one of the best ROI investments you can make.

Wet Bar or Kitchenette: +$5,000–$15,000

Custom wet bars with cabinetry, a sink, plumbing, and a mini fridge are very popular in Northern Colorado. A full kitchenette with appliances runs higher.

Egress Window: +$2,500–$5,500 each

Required to legally call a room a bedroom. We cut the opening, install window wells, and meet all Colorado code requirements.

Home Theater: +$5,000–$20,000+

Dedicated circuit wiring, acoustic treatment, projector mounting, custom built-ins and soundproofing can add significantly to the scope.

What's the ROI on Basement Finishing in Longmont?

In the Boulder County and Northern Colorado market, finished basements typically return 70–80% of project cost at resale — one of the highest ROI home improvements available. In a tight inventory market like Longmont, a finished basement can make the difference between a quick sale at asking price vs. sitting on the market.

How to Get an Accurate Quote

Cost estimators and online tools give ballpark ranges, but the most accurate number comes from an on-site visit. At Basements.com, we provide free, detailed, itemized written estimates — no obligation. We measure the space, discuss your vision, and give you a real number within a few days.