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How to Finish a Basement: Framing and Insulating

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.

By the DIY experts of The Family Handyman Magazine

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    Plan ahead. You'll need to submit a plan to your building inspector and obtain a permit. You’ll also need to detect and remedy any moisture problems in your basement before you begin insulating and framing.

Planning and getting started

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.

Get started by making a scale drawing of your plans to submit to your local building inspections department. 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. If you’re uncertain about the best use of space, hire an architect to help with the design. The permit itself will outline at what stages inspections are required. 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. 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.

If you have a wet or damp basement, you must deal with the problem before you get started. 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 and framing

Start the job by gluing 3/4-in. extruded foam insulation to rim joists and foundation walls (Photo 1). Extruded polystyrene foam (imprinted on each sheet; see Photo 5) can be yellow, pink or blue depending on the manufacturer. Avoid “expanded” foam insulation (the type that has little white beads pressed together) 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. Then caulk seams and gaps to seal against air infiltration (Photo 2). You'll add fiberglass later for a higher R-value. The foam greatly reduces heat transfer through the masonry and framing, and it eliminates the need for a plastic moisture barrier later. Be sure to use adhesive formulated for use with foam (about $3 per tube). Conventional construction adhesive won't work.

Next frame the stud walls 1/2 in. away from the foam (or more if your foundation's uneven). We show the “stick framing”method of wall building. That means that you cut, lay out and install the top and bottom 2x4s (plates) first (Photos 3 – 6). Then you'll custom-cut the studs to length and toenail them into place (Photo 7). This method is great for basements because it makes it easy to frame around overhead obstructions and customize stud lengths to handle uneven floors. It can be tough to preframe a wall (as you would normally do with a shed or addition) and raise it in place with a floor overhead. Be sure to use pressure-treated wood for any wood that has contact with concrete surfaces.

Lay out stud locations by laying both plates side by side and then hook your tape measure on one end and mark studs every 16 in. For walls longer than 8 ft., subtract 3/4 in. from each location (e.g., 15-1/4, 31-1/4 in., etc.). That's so drywall will fall in the center of studs. Otherwise, the sheets will fall just short of a stud at each joint.

To position the top plate, tape your level to a straight 2x4 and mark the blocks or joists at either end of the wall. Then snap a chalk line between them. Top plates that run perpendicular to floor joists can be nailed (with 16d nails) or screwed (with 3-in. screws) to the bottom of every other joist. If walls run parallel to floor joists, you'll need to nail or screw blocking in between the floor joists about every 3 ft. or so (Photo 5). For most, running in screws is easier than overhead nailing. Likewise, it's easier to predrill and drive concrete screws rather than pound in concrete nails when fastening bottom plates.

When you're framing half walls (Photo 8), make all of the studs the same length and cut them so the wall will be even with the top of the masonry. The wall may be uneven because of floor inconsistencies, but you can always sight along the top plate and then shim it until it's flat before installing the finished top cap. When plumbing the top of the half wall (Photo 9), be sure to sight along its entire length to make sure it's straight.

Building soffits

Most basements have ductwork and plumbing mounted at the ceiling along an existing wall. Boxing in those pipes and ducts and then drywalling the assembly is the best way to conceal them. The whole structure is called a soffit. Begin by measuring to the floor to find the lowest pipe or duct in the room; that'll define how low the soffit must be. Mark a point 2 in. lower on the wall to allow space for the framing and drywall (Photo 1) and nail on a 2x4 nailing strip using the chalk line to position the bottom of the strip. Then snap another line on the bottom of the joists with a 2-1/2 in. clearance. It's easiest to preassemble the 8-ft. long soffit side sections and screw them to the bottom of the floor joists (Photos 2 and 3). If soffits end at walls, build the walls first.

Framing partition walls

Partition walls are any walls that aren't against exterior foundation walls or walls that support floors above. Lay out partition walls by snapping chalk lines to mark both sides of the bottom plates (Photo 1). That keeps you from building walls on the wrong side of single lines! Mark door openings on the floor (Photo 2) to avoid putting glue under doors. Frame partition walls as you did the outside walls, again installing blocking between joists wherever it's needed. Add 2x6 backers on walls that meet partitions (Photo 1). They provide support and nailers for drywall. Before you tie the partition walls to exterior stud walls (non-masonry, without foam), staple 2-ft. wide strips of polyethylene over the 2x6 backers (Photo 2). That way you'll be able to seal this type of outside wall with a continuous moisture barrier in cooler climate zones.

In a basement, the top and bottom plates are often different lengths. That's because top plates may project past foundation walls and be longer or run into soffits and be shorter. (See both cases in Photo 3.) When you line up the plates to mark stud locations, be sure to account for differences (Photo 2).

Frame the door openings 2-1/2 in. higher and 2-1/2 in. wider than the door you're installing. This “rough opening” allows adequate space for the door plus its frame. Use a regular stud plus a “trimmer” on each side of the door (Photo 3). If you have low headroom, you may need to cut your doors down or special-order shorter ones. Remember to allow overhead space for the door trim. Trim that's either missing or ripped too narrow over doors with inadequate clearance will really detract from the appearance of the room.

TIP: Partially cut through the underside of the bottom plate at the edges of the door rough opening to make removal easier later on.

Framing around obstructions

Nearly every basement has something that will project past finished surfaces. That can include beams, posts, drain lines, water piping or surface mounted wires. It’s a simple matter to frame or fur out around projections and then drywall and finish them to blend in with surrounding surfaces. You'll have to maintain access to other things like electrical junction boxes and plumbing shutoffs and cleanouts. If you need future access to anything, just frame around it and cut out the opening when you drywall (Photo 1). Then, after taping and painting, screw a “return air” grate over the opening to conceal it but still have access. Return air grates are available in various sizes for about $5 at home centers. Check the sizes of available grates and frame the accesses slightly smaller.

Sometimes furring down part of or the entire ceiling is the best way to bury surface-mounted pipes or wires. Use either 2x4s or 2x2s running perpendicular to the joists to add 1-1/2 in. of dead space so you can drywall over the top of everything (Photo 3). Be sure to run all the wiring and other things you might want before hanging the drywall.

If you have a lot of deep projections from the ceiling or you need a lot of access, consider installing a suspended ceiling rather than drywalling. The downside is that you'll lose at least a few additional inches of ceiling height.

Finish round steel columns by framing around them with 2x4s. You can then face the framing with drywall or decorative wood as shown in the opening photo.

Back to Top

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

A table saw will make ripping the plywood soffits easier.

Required Materials for this Project

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

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

Comments from DIY Community Members

Share what's on your mind and see what other DIYers are thinking about.

1 - 20 of 33 comments
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RSH

May 09, 8:20 PM [GMT -5]

As a life long builder/ general contractor I must say Your June 2013artical about finishing a basement contained some of the worst advice tat I have ever seen given by any DIY publisher> bar none.

May 08, 10:50 PM [GMT -5]

My builder rolled out insulation on my walls covered in foil. Should I just stud out over that? Also is a drop ceiling better around ductwork?

March 12, 10:53 AM [GMT -5]

This project is georgeous. But time is money. I chose to do it with a DIY basement finishing kit. Fast easy and mold free. Damp basement in the spring and fall. I did a drop ceiling and fire blocked with drywall. All in all small area 20 by 20 cost me $6000.00 but I was done fast. My walls were up in one weekend! Wiring was fast, but had to wait on electrician. Drop ceiling and trim took a weekend. Still need to paint..gotta choose a color we can both agree on. Tax refund helped too!

November 03, 8:56 AM [GMT -5]

I did my basement already. I am glad my I didn't put the insulation right against te wall but I didn't have furring strips. I used this do it your self wall panel. I didn't have to frame it came with aluminum brackets and gave an air gap. But it did use the white foam you don't recommend, but it was thick and is R-11 and since it was encapsulated between some cement like board I think it will lasst. Anyway it is warrenteed for life. I liked it because if we get a flood like the east coast did my wall are not foing to fall apare. they sent a free sample to me and I did like the guy on the phone said.."stick it in a bucket of water for a week and a peice of drywall then call me." I once had water from my icemaker in the basement it was a mess. Anyway I used these wall panels from a local factory called wahoo they are in dexter mi for what its worth.
enjoyed your knowledge I am good but not that good and this was easy and fast.

October 23, 1:59 PM [GMT -5]

Thanks for all the help! Now that I have an idea of what I'm doing I guess I should find some decent insulation in Buckeye AZ. About how long of a process is this project?

May 21, 8:51 PM [GMT -5]

i need to finish my basement but i need to add more support to the floor in my living room and kitchen that is directly above my basment. how do i go about doing this or where do i find it

May 21, 8:51 PM [GMT -5]

i need to finish my basement but i need to add more support to the floor in my living room and kitchen that is directly above my basment. how do i go about doing this or where do i find it

May 21, 8:51 PM [GMT -5]

i need to finish my basement but i need to add more support to the floor in my living room and kitchen that is directly above my basment. how do i go about doing this or where do i find it

March 19, 7:15 PM [GMT -5]

I've lived in a older frame house for 13 years - and for 12 of them, I've puzzled how to even start the project diy, to finish my basement, I have never been able to find, at least in print, of how to even begin the challenges this basement presents:

The foundation walls are white-washed, white-washed large stones, set in cement. To say that the walls are "slightly uneven", is the understatement of the century! So, there's my uneven surface problem - Now, how does one fasten ANYTHING, into granite rocks? Stone-Mason? Dynamite??

I know thatt many of these old type, "rustic" foundations must exist, and many places, I presume, besides north-central Wisconsin... Is there any technique out there for dealing with these "antique" rustic, foundations, to finish a basement made of them?

Thank you - I'd love to hear how to do this!

March 06, 8:45 PM [GMT -5]

Are plans available for the entertainment center pictured - great looking entertainment center!

John

March 06, 8:43 PM [GMT -5]

Are plans available for the entertainment center pictured - great looking entertainment center!

John

March 06, 8:42 PM [GMT -5]

Are plans available for the entertainment center pictured - great looking entertainment center!

John

January 29, 2:02 AM [GMT -5]

When I completed my first basement in NE Ohio - known for cold winters, I listened to a friend who is a local home builder. He said a basement that is primarily underground - 6' or more is genrally about 60 - 65 degrees year round -without insulation just the block or solid concrete walls. He recommended I use no insualtion, no vapor barrier and install the 2x4 studs directly against the walls and then the drywall - no insulation and no vapor barrier. Well - he was right! Saved money on installation and in heating and cooling. Think about it - one of the big things currently in HVAC these days are the systems that install grothermal assisted heat pumps to utilize the stable temperature below grade several feet. Same principle. And if you are worried about moisture - no problem. IWhat proved it to me was I installed an access plate for my water shutoff valve that was about 4' off the floor making it about 3' below grade. Whenever I pulled the access cover I could feel the air moving - and air moving means little to no chance of condensation. I know many will disagree but I did this in the mid- 1990's and when I moved in 2005 still had absolutely no issues what so ever with moisture or condensation or cold. I will do the same thing once again in my current home that has 8" concrete walls versus block walls.

January 15, 11:13 PM [GMT -5]

Hi we are in the design process for finishing our basement and was wondering if you can use 1x4 @ 12"oc furring anchored thru the polystyrene insulation foam into the concrete wall?( We have limited space and want to utilize all of it). If we have to build out the wall with 2x6 then we are loosing all of this space. Can you then fasten the sheetrock to the furring without having any moisture issues? We appreciate any feedback.
The Flemings

January 15, 4:20 PM [GMT -5]

The plan shown shows the stud wall spaced 1/2" off the foam insulation. Other plans I've seen say to put them in contact, to prevent any air circulation (which could encourage condensation/mod growth). Any comments on which is better?

I've also seen where people only lay foam along the top of the wall (insulating the part of the wall that is above ground, most bang for the buck). The bottom half of the wall is left uninsulated, allowing any condensate that does form to have a clear path to dry on its own. Any comments woudl be appreciated.

December 16, 10:53 AM [GMT -5]

I used 2 inch pink board on my walk-out basement. I have two main walls that are block and are exposed (not under ground). The 2" pink board has an R value of 10 and cost me $22 per sheet at H.D. The 1.5" was $20 per sheet and has an R value of 7. The price difference wasn't worth giving up the R value of 3. I read somewhere that you should use no less than 1.5" pink board because the thinner boards do not give you enough of a vapor barrier. Not sure if this is true or not? I taped my seems with Tyvek house wrap tape and used foam board glue ($3.69 per tube) to stick it to the walls. The foam board glue works well because its pasty and sticky like toothpaste which gives a good initial hold. I am planning on using 2x4 for my walls and I might use fiberglass insulation to get a better R value.

** Side note: I also used UGL paint on my walls prior to installation...never had any water problems but just wanted to be extra safe.

October 04, 9:20 AM [GMT -5]

My builder has fastened rolls of insulation (foil covered) to the walls of my basement. Do I have to remove these or can I frame alongside these?

April 24, 4:23 PM [GMT -5]

Project in-process. Ready to frame. Doing project as outlined.
Can Kraft faced insulation be used in the stud wall? For some reason unfaced insulation is hard to come by where I live. Kraft faced and wrapped in plastic insulation is everywhere though.
Thank you for a great project!

March 25, 3:19 PM [GMT -5]

i was wondering about fireblocking. Since your frame is 1/2 inch from the wall, I would thik that you need some kind of fireblocking at the top at the very least. Since this is now required in most states, d oyou addresss this anywhere?

Very nice work.

January 17, 12:35 AM [GMT -5]

pigpen,

your water heater and furnace have specific requirements set by both building codes and the manufacturer. The most important is fire resistance of the surround. Make sure you use fire resistant drywall to finish the closet for your mechanicals. A water heater's space requirement is usually printed on the label. Generally you only need a setback from the gas inlet and, of course, a means to take it out when it needs replacing. The furnace is more tricky. Newer homes may have a fresh air inlet from the outside. This is because they are wapped so tight (insulated) that you need a source of exterior air to maintain equal pressure in your home. Older homes generally get this "fresh" air from all the leaks and cracks in walls, windows, doors. Regardless, when you enlose your furnace, you need to give it a source of replacement air, beyond the cold air return. Also, make sure you provide cold air returns in your finished basement since you will be closing off the existing duct work from your new living space.

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