How Much Does It Cost to Finish an Attic in 2025?

This article was updated using automation technology and thoroughly reviewed for accuracy by HomeAdvisor Editor Ryan Noonan.

The average cost to finish an attic is $20,000, with most homeowners spending between $7,500 and $35,000. Prices can be as low as $4,000 or as high as $300,000, depending on the project's complexity and scope. This equates to $30 to $60 per square foot. Finishing your attic transforms unused space into valuable living areas and can significantly increase your home's value. 

Attic Finishing Cost Factors

The total cost to finish your attic depends on various factors, including square footage, labor, and permits. Here is a breakdown of the cost factors that will determine your final costs.

Size

The size of your attic significantly impacts the cost. At $30 to $60 per square foot, a standard-sized attic conversion ranges from $4,000 to $16,000.

Materials

Finishing an attic costs between $30 and $60 per square foot, which includes both labor and materials. Choosing high-end or custom-made materials will increase your costs significantly.

Labor

Labor costs make up about 10% to 20% of your total project budget. The exact amount depends on the specific tasks involved in your attic finishing project. For example, you may need to hire a plumber, electrician, structural engineer, and painter, each with their own rates. 

Permits

Building permits cost between $100 and $1,500 or more, depending on your local regulations and the scope of work. Permits are often required for electrical, ventilation, plumbing work, or structural changes. Your attic remodel contractor typically handles permit requirements, but it's wise to check with your local building department to understand specific costs.

Cost to Finish an Attic by Task

Depending on what your plans are for the bedroom and the current state of the attic, you may not need a full conversion or renovation. You may only need a handful of these tasks completed to finish your attic bedroom if much of the work is already complete. Take a look at some of the most common tasks involved that make up the cost of your bedroom remodeling project.

Subflooring

In an attic space, laying a subfloor costs $3 to $10 per square foot. You'll need to lay a subfloor if the attic joists are visible. The subfloor goes down after electricals and ventilation are in place. It's also a good idea to insulate beneath the subfloor for energy efficiency and sound-dampening.

Electrical

Electrical work costs $750 to $3,200 for an attic refinishing project. This can include tasks like installing outlets, new wiring, and light fixtures.

Doors

Adding a new door costs $375 to $1,125, depending on the type of door you choose. However, if your attic access is on the home's exterior, you'll want an external security door, which can cost up to $1,200. Higher end doors, such as pocket doors or sliding doors can run you up to $2,500.

Drywall

Drywalling costs an average of $2,100. It's installed when the wiring, insulation, and ventilation systems are all in place and is an essential component of finishing the attic to turn it into a livable space.

Insulation

Attic insulation costs an average of $2,500. If you're installing insulation in an already partially finished space, blown-in insulation is the most cost-effective solution. If, however, you haven't hung the drywall yet, you can install structural insulated panels, which, while more expensive, are stronger, longer-lasting, and more energy-efficient.

Windows

The cost to add windows in an attic is $200 to $10,000 per window. The huge cost range depends on the type of windows you want, with a like-for-like window replacement costing from $200. Adding skylights and corner windows typically costs around $3,500 each, while floor-to-ceiling windows, which are great for creating breathtaking views, cost up to $10,000 each.

To get more usable space and let light into the attic, you can add a dormer instead of a regular window. Installing a dormer window (or dormer addition) typically costs $8,000 to $30,000, around $12,000 each on average.

Floor Joists

Repairing or replacing floor joists in an attic costs an average of $6,000. You may not need this part of the project at all, but your attic remodeling pro will be able to assess the existing joists to see if they need any remedial work. The joists must be strong enough to bear the weight of the finished room, all its furnishings, and the people using the room. The baseline is that the floor must be able to support a load of 30 pounds per square foot.

Plumbing

Plumbing costs anywhere from $1,000 to $10,000 and is dependent on whether the rough-in is already in place, whether you need to run new plumbing lines, and how many fixtures you want added. The further away the existing plumbing is, the more it costs to run new lines to the attic due to the increased distance and complexity.

Stairway

Adding a stairway to an attic costs between $950 to $3,200. If a safe staircase already exists, then you won't need to pay for this addition. A simple internal stairway that's an extension of your existing stairs is the most affordable and space-saving option. You can also have an external stairway added if you've got or want to add an exterior access door. Where a stairway isn't possible, you can add an attic ladder that costs $400 to $1,000.

HVAC

To provide conditioned air in this newly livable space, you can install new ductwork and vents in the attic. This typically costs $1 to $3 per square foot. Alternatively, you can install a ductless or mini-split system at an average cost of $2,000 to $4,000 for a 12,000 BTU system.

DIY vs. Hiring a Pro

While it may be tempting to tackle an attic conversion yourself, this project involves complex tasks that require professional skills. Many municipalities mandate that licensed professionals handle electrical and plumbing work to meet building codes. You can reduce costs by handling some finishing tasks yourself, such as painting walls, installing flooring, or adding window treatments. Doing so can save you around 40% on labor costs. However, for critical elements, it's best to hire a home remodeling professional to ensure your attic finishing project is completed safely and up to code.

How HomeAdvisor Gets Its Cost Data

No place is more important than your home, which is why HomeAdvisor connects homeowners with local pros to transform their houses into homes they love. To help homeowners prepare for their next project, HomeAdvisor provides readers with accurate cost data and follows strict editorial guidelines. After a project is complete, we survey real customers about the costs to develop the pricing data you see, so you can make the best decisions for you and your home. We pair this data with research from reputable sources, including the U.S. Bureau of Labor Statistics, academic journals, market studies, and interviews with industry experts—all to ensure our prices reflect real-world projects.