How to Finish, Frame, and Insulate a Basement

With special framing and insulating techniques, your basement can be as comfortable as any other room in your home. Find out more about insulating basement walls and framing basement walls here.

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Turn your unfinished basement into beautiful, functional living space. Framing basement walls and ceilings is the core of any basement finishing project. Learn how to insulate and frame the walls and ceilings, build soffits, frame partition walls and frame around obstructions.

Tools Required

  • Caulk gun
  • Chalk line
  • Circular saw
  • Drill bit set
  • Drill/driver - cordless
  • Dust mask
  • Hammer
  • Hammer drill
  • Hearing protection
  • Level
  • Safety glasses
  • Sawhorses
  • Speed square
  • Stepladder
  • Tape measure
  • Tool belt
  • Utility knife

Materials Required

  • 1-5/8-in. screws
  • 1/2-in. plywood
  • 16d nails
  • 2-1/2 in. concrete screws
  • 2X2 lumber
  • 2x4 lumber
  • 3-in. screws
  • 8d nails
  • Construction adhesive
  • Extruded polystyrene insulation
  • Fiberglass insulation
  • Foam adhesive
  • Treated 2X4 lumber

Your basement can be more than a utility and storage area. With some forethought and good techniques, you can make it as warm, comfortable and inviting as any other room in the house. But, make no mistake about it: Finishing a basement is a big job. In this article, we’ll focus on the framing and some unique problems, such as:

  1. Finishing against cool masonry walls without creating moisture problems.
  2. Framing around obstructions like posts, heating ducts and pipes.
  3. Keeping access to valves and cleanouts.
  4. Framing and finishing a wall that’s half masonry and half wood frame. You only need basic carpentry skills for framing and one special tool—a hammer drill for concrete fasteners.

Video: Working With Mineral Wool Insulation

Project step-by-step (21)

Step 1

Submit Building Plans

  • Make a scale drawing of your plans to submit to your local building inspections department.
    • Note: Your plan should include wall dimensions, window and door sizes, and each room’s purpose (e.g., family, bedroom, etc.) along with any special features like fireplaces. Some rooms may require large windows, called “egress” windows, for fire safety. Ask your building inspector if you need them. Also measure the future finished ceiling height and low-hanging pipes or ducts that’ll lower headroom.
  • Sketch the details of the exterior wall construction you intend to use as we show in this article.
    • Pro tip: If you’re uncertain about the best use of space, hire an architect to help with the design.
  • If you choose to do your own electrical work, draw up and submit that plan as well.
  • With your plan and permit in hand, clear everything out of the basement and you’re ready to go.
    • Pro tip: Walk around the basement with caulk and cans of spray foam and plug every gap you can find between framing and masonry and around pipes or wires that penetrate the rim joist or exterior walls. This is your last chance to seal air leaks from the inside.

Step 2

Resolve Any Dampness Issues

To tell if walls are damp from exterior water or just condensation from humid interior air, tape a 2-ft. square sheet of plastic to the masonry. If moisture collects on the front of the plastic, you have condensation. The method we show for finishing will take care of that problem. If moisture collects on the backside after a few days, then water is wicking through the foundation wall from outside. The basement should be treated the same as if it were leaky. If you have regular seepage or water puddling after storms (even once every few years), you have to fix it permanently before finishing. Remedies for damp or wet basements can be as simple as rerouting downspouts, regrading slopes away from foundation walls, or applying water-resistant paints to interior surfaces. As a last resort, hire a pro to install perimeter drains and a sump pump. The bottom line is that it’s senseless to spend time and money finishing a basement if leaks or moisture will ruin your work or cause mold to grow.

Insulating Basement Walls

  • Start by gluing 3/4-inch extruded polystyrene foam insulation to fit against the rim joists and foundation walls.
    • Note: Extruded polystyrene foam can be yellow, pink or blue depending on the manufacturer for insulating basement walls. Avoid “expanded” foam insulation (the type that has little white beads pressed together) when insulating basement walls because it isn’t as durable and has a lower R-value.
  • Make cuts by snapping chalk lines to mark and then score it with a utility knife as deep as the blade will penetrate. Then snap the sheet just like you cut drywall.
  • Carefully cut around obstructions and fill spaces with small chunks of foam wherever it’s needed, working for tight fits.
  • Spread a 1/4-inch bead of adhesive on masonry walls and press the sheets into place.

Insulating basement walls and framingFamily Handyman