How to Finish a Basement Wall

We compare the pros and cons of two good options.

We show two good ways to insulate and finish a basement or concrete wall. A 2x2 wall saves space and a 2x4 wall is easier to assemble and insulate. Both will create that snug extra room you need.

By the DIY experts of The Family Handyman Magazine

TIME

Multi-day

COMPLEXITY

Moderate

COST

$100 - $500

Solve all moisture problems first

Finishing a portion of a basement is an inexpensive way to gain valuable space for a family room, game room or other use. The big question is how to finish the foundation walls. We'll assume that you have either a poured concrete or a cement block masonry wall. With either surface, the finishing options are the same.

Before beginning any work, you must determine whether your basement has any moisture problems. If your foundation walls are only damp on humid summer days, fine—you're good to go with the methods we recommend. But if you have any problems with standing or leaking water in the spring or during heavy rains, you've got some “prework” to do.

Fixes usually are as simple as adding or repairing gutters and downspouts or adjusting the grade to direct runoff water away from the house. But serious water problems may call for drastic measures like interior or exterior drain tiling, or exterior waterproofing, which could mean digging around the house or tearing up part of the slab. You must solve all water problems, or you'll risk boxing future water in behind a finished wall, ruining it. You'll end up spending hundreds of bucks re-remodeling a recently finished lower level.

Just about every carpenter or building inspector has a different opinion on how to finish walls against masonry. The methods we'll demonstrate work well in most conditions, but consult with your building inspector before beginning any work to make sure you're meeting building codes in your area.

There are two methods of finishing against masonry: fiberglass-insulated 2x4 walls and foam filled 2x2 walls. Both methods include a 3/4-in. foam moisture barrier between the framing and the foundation wall to eliminate condensation from interior humidity and to protect the walls from exterior moisture. Tack the foam to the foundation wall with a few blobs of foam construction adhesive to hold it while you frame the walls.

Don't cover a wet wall!

Block and concrete walls below grade can feel damp on a hot and humid summer day—that's normal. But beware of walls that get wet after a good rain or during spring thaws, or that have areas that never seem to dry out at all.

You have to deal with water infiltration issues before you can begin framing. Covering a wet wall creates a perfect environment for mold and rotted wood. And caulking a crack that seeps water is not a solution. Landscaping, gutters, drain tile—do whatever it takes to solve your water problems before you begin your project!

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Seal the wall

Once you've solved the moisture problems, seal the foundation walls. Start by rolling on a masonry waterproofing product. This step is only to help prevent water that naturally migrates through concrete through a capillary effect.

Roll-on waterproofing is in no way a permanent solution to a bulk water infiltration problem. If the walls are damp from condensation, dry them out with a humidifier before using the product. One choice is DRYLOK, which is available at home centers and hardware stores.

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The two ways to finish your basement walls

Just about every carpenter or building inspector has a different opinion on how to finish walls against masonry. The methods we'll demonstrate work well in most conditions, but consult with your building inspector before beginning any work to make sure you're meeting building codes in your area.

There are two methods of finishing against masonry: fiberglass-insulated 2x4 walls and foam filled 2x2 walls. Both methods include a 3/4-in. foam moisture barrier between the framing and the foundation wall to eliminate condensation from interior humidity and to protect the walls from exterior moisture. Tack the foam to the foundation wall with a few blobs of foam construction adhesive to hold it while you frame the walls.

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Method 1: A conventional wall

The easy finishing method is to simply frame conventional 2x4 stud walls with pressure treated bottom plates (the 2x4s the wall rests on) and fill the walls with fiberglass insulation. Hands down, it's the way to go—if you have oodles of space in the room you're finishing. Two-by-four walls are quick to install and there's plenty of space for electrical work. Plus, you don't have to hassle with fastening furring strips to concrete, and it's easier to cut fiberglass insulation than to fit foam. The downside is that each wall steals nearly 6 in. of floor space from the perimeter of the room.

Look at the photo below to see the details. Note that the wall is pushed against the foam and then anchored to the slab with concrete screws and to the ceiling with 3-in. drywall screws. Don't install a vapor barrier between the fiberglass and drywall because moisture will be trapped in the wall.

2x4 Framing Method

Pros: Fast to build, lots of room for wiring and plumbing.
Cons: Gobbles up 38 sq. ft. of space in a 20 x 36-ft. basement.

Note: You can download this cutaway photo and enlarge it in the Additional Information below.

2x4 Framing method
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Method 2: 2x2 furring strips and foam

To save precious floor space, use a thinner wall composed of 2x2s and foam insulation attached directly to the wall. Nail or screw a 2x2 to the bottom of the floor joists at the top of the wall, and screw a treated 2x4 flat against the bottom of the wall through the foam and into the concrete with 3-in. concrete screws. Then lay out the stud positions on the plates. Screw the treated 2x2s to the wall with three evenly spaced screws and fill in between with foam insulation ripped to fit. Hang the drywall with 1-1/4 in. drywall screws.

The downside is that electrical outlets and switches have special installation requirements. Cables must be at least 1-1/4 in. behind the front of the wood framing to prevent fasteners from accidentally piercing and damaging the cable. Use 1-1/4 in. deep steel boxes and run cable through EMT (electrical metallic tubing) between the furring strips to the boxes. Boxes and conduit straps are screwed through the foam and into the masonry with 1-1/2 in. concrete screws.

To save precious floor space, use a thinner wall composed of 2x2s and foam insulation attached directly to the wall. Nail or screw a 2x2 to the bot

Pros: Space efficient.
Cons: Electrical installation is tougher.

Note: You can download this cutaway photo and enlarge it in the Additional Information below.

2x2 Furring strip method
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Expert advice on conventional framing with 2x4s

Furring out a basement wall with 2x2s is pretty straightforward. Snap some plumb lines and attach the furring strips directly to the masonry wall with glue or concrete screws or nails.

Framing with 2x4s is pretty straightforward, too, but there are a few things to keep in mind. It's like installing a 2x4 wall between a subfloor and ceiling joists, but the floor is concrete and there are usually lots of pipes, ducts and conduits the frame around. Here are some tips to make framing your basement with 2x4s easier.

Meet the expert

Phil Geis has been a framing carpenter for more than 20 years. He started out helping his uncle on remodeling projects while he was still in high school. He and his crew have built more than 300 new houses and breathed new life into dozens of old basements.

Phil Geis, framing carpenter
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Install blocking between joists

When the floor joists run parallel to the wall you're building, you'll need to install blocking for attaching the top wall plate. Screw or nail one side of the block through the joist, and secure the other side to the sill plate. Use treated lumber if the brace will come in direct contact with bare concrete. It may be easier to install the braces before you install the foam board on the walls and insulate your rim joist. (Search familyhandyman.com for “insulate rim joists.”) Phil places his blocks 2 ft. apart so they work as drywall backers too.

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Install foam board

After your waterproofing has dried, install 2-in. extruded polystyrene (XPS) foam board insulation. Be sure you use XPS—other types are not as moisture resistant. Stick it to the wall with a construction adhesive that's specifically designed for foam—regular construction adhesives will melt the foam.

Apply the adhesive in vertical strips in the middle of the wall. If some water does get behind the foam, adhesive applied horizontally could cause the water to pool up and lengthen the time it takes to dry up. Run a continuous bead of adhesive at the top and bottom of the wall, and tape all the seams. This will help keep warm air in the room from getting behind the foam and condensing on the cool concrete walls. To ensure a good seal, Phil prefers to caulk the bottom after the foam is installed.

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Snap lines on the floor

Snap a line on the floor 4 in. away from the foam as a guide for the bottom plate. This will leave a 1/2-in. gap between the bottom of the new wall and the foam. That'll allow a bit of wiggle room if the foundation walls aren’t perfectly plumb or straight.

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Assemble the walls on the ground

If you have the space, it's faster and easier to assemble a wall on the ground. Sight every stud for a “crown” (a slight curve on the narrow side of the board), and mark an “X” on the crown. Have all the crowns face the same direction. If you don't, you’ll end up with a wavy wall.

It's easier to assemble your wall with the crowns up; that way both ends of the studs are solidly on the ground when you attach the top and bottom plates, instead of acting like rockers on a rocking chair. Build the wall so it can be tipped right up; there's usually not enough room to swing the whole wall around if you don't.

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Tip up the walls

It's usually easier to tip a wall up with the bottom plate against the wall, but if the floor joists are sagging or there's ductwork in the way, you may have to lift the top of the wall in first and slide the bottom plate into place. If you're working alone, don't build a wall too heavy to lift. Save your back by building smaller sections and tying them together after you set them in place.

Build the walls short

If you need to pound the walls into place with a sledgehammer, you've built your walls too tall. There's no reason that the top plate has to be tight against the joists—that's what shims are for. Measure the distance from the floor to the joists at several locations and build your wall at least 1/4 in. shorter than the shortest measurement. Trying to force a wall into place can raise the joists, which could wreak havoc with drywall joints and flooring on the rooms above.

Measure the distance from the floor to the
joists at several locations and
build your wall at least 1/4 in. shorter
than the shortest measurement.
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Fasten the bottom plate

Phil fastens his walls to the floor with construction adhesive and a powder-actuated tool (PAT). He spaces fasteners every 6 ft. and within 6 in. of each end. Most residential-grade PATs are powered by .22 caliber blank cartridges, which drive in nail-like fasteners at a velocity of about 300 ft. per second. Prices range from $20 for the one in this photo up to $80 for models that have a trigger and don't require a hammer to fire them. Get 2-1/2-in. fasteners so they will penetrate about 1 in. to 1-1/4 in.

Wear safety glasses, and hearing protection is a must because these suckers are loud. Phil usually shouts out “Fire in the hole” to warn other people in the area. For more information on PATs, search familyhandyman.com for “powder actuated tools.”

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Plumb and secure the top plate

Instead of snapping a line for the top plate, Phil plumbs the wall about every 4 ft. using an adjustable level that reaches from the bottom plate up to the top. If you don't own a $300 plate level, use at least a 4-ft. level, and try to find the straightest studs to use as a guide. You need shims only about every third joist, but nail the top plate to every joist. It's not necessary to align the studs directly under floor joists, but it's a good idea if you plan to run ductwork or plumbing in the walls.

Build in place when necessary

If your floor is horribly out of level, or if you're framing around a window, it may be best to “stick frame,” nailing one stud at a time instead of building the wall on the floor.

Start by fastening your bottom plate, and then use a straight stud and a level to plumb up to find the location for your top plate. After you snap a line and fasten your top plate, plumb up again and mark the location of your first stud on both plates. Mark the rest of the stud locations on the plates using those marks. Toenail each stud into place with two nails on one side of the stud and one on the other.

Sometimes it makes more sense to
stick-frame a wall.
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Inside corners

When he frames inside corners, Phil turns the last board on the first wall sideways and overlaps it about halfway past the connecting wall. This way he can fasten the two walls together and still have a surface for attaching the drywall.

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Build out around windows

Windows set in a block or concrete wall will need wood around them in order to attach the drywall or jamb extensions. If there's room, use foam under the boards, and tape the seams to the foam you've installed on the wall. If there's no room for foam, make sure to use treated lumber, but still tape the seams. Construction adhesive and concrete screws work best to attach these boards. Install the wood around the window before you build your wall. That way you'll know exactly where the new wall framing needs to be.

Don't forget drywall backers

It's a lot easier to add drywall backers while you still have all your framing tools out and before you fill the wall cavities. So before you pack it up, walk around the entire work area and make sure the ceiling and all walls have a sufficient nailing surface for the drywall. The top of outside corners, perpendicular intersections, and walls that run parallel to the joists are three of the most common areas where you'll need to add backers.

The top of outside corners, perpendicular
intersections, and walls that run parallel to the
joists are three of the most common
areas where you'll need to add backers.
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Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Hammer
  • Air compressor
  • Air hose
  • Tape measure
  • Circular saw
  • Caulk gun
  • Corded drill
  • Chalk line
  • Level
  • Impact driver
  • Extension cord
  • Framing square
  • Hearing protection
  • Knee pads
  • Safety glasses
  • Sledgehammer
  • Utility knife

Depending on the method you choose, you'll need a hammer or a hammer drill to frame the walls and connect them to the concrete foundation.

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

  • 2x4 or 2x2 lumber
  • 2x4 green treated lumber
  • Fiberglass insulation
  • Rigid insulation

You'll also need conduit or cable for electrical boxes