DIY Basement Finishing: Walls Framing

Finishing our basement was something we had been wanting to do for a long time. We had discussed different layouts, ideas and changed our minds many times since we moved into this house. One thing we knew for sure was that we didn’t want a bunch of bedrooms and bathrooms that we don’t need. We wanted as much open space as possible for a home gym and a big recreation room.

After converting one of our bedrooms into an office, and getting the other one set up for kids, we realized that, after all, it made sense to build an extra bedroom and a bathroom down there. Our family visits often, and after the two bedroom conversions, they had to stay in hotels in their last few visits.

Due to the amount of work and cost, we always planned to finish it in phases. But because we need the space for friends and family to stay when they visit, we decided to start building a bedroom and a bathroom instead of the gym and recreation room. This meant less framing, drywall, and materials in general, so it worked out well for us anyway.

 

A PROJECT WE DID NOT PLAN TO DO

Before we got to framing, we had to cut the concrete slab open to fix the sewer pipes for the bathroom. They were too close to each other and not in the best positions. The shower drain was so close to the concrete wall that it was not going to be possible to frame a wall and properly set a shower pan. The toilet drain was way too close to the shower and sink drains.

We ended up moving them quite a bit to fit a 60” shower pan, the toilet and a 48” vanity.

 

To get the new walls as close to the concrete wall as possible, we also removed part of the insulation.

DIY BASEMENT FINISHING: STEP BY STEP BASEMENT WALLS FRAMING

Before we even started, we made sure we had all the necessary tools and materials we needed for it. Because we are always working on different projects, we had most of the tools, except the powder actuated nail gun and the laser level, which we borrowed from a friend. Although we had never use it before until now, we bought the framing nailer a few months ago knowing that we were going to be using it for this project. The complete list of tools and materials  includes:

• Pressure Treated and Regular Framing Lumber
• Screwdrivers & Hand tools (Always useful)
• Chalk Line
• Measuring Tape
• Pencil & Framing Square
• Miter Saw & Circular Saw
• Powder Actuated Nail Gun (If framing on a concrete slab)
• Powder Loads
• Drive Pins With Washers
• Framing Nailer
• Framing Nails
• Air Compressor
• Construction Screws (Optional)
• Drill & Drill bits
• Level
• Laser level (optional but makes your life way easier)
• 6” Nails (For Floating Basement Walls)

STEP 1: HOW MUCH LUMBER DO YOU NEED TO FRAME YOUR BASEMENT?

It is helpful to have as much of the lumber you need to frame your basement before you start the project. You need enough lumber for the pressure treated plates that will be anchored to the concrete slab, the top and bottom wall plates and the studs (plus any soffits, etc.).

To determine the amount of lumber you need for the pressure treated plates and the top and bottom wall plates, just calculate how many linear feet of walls you have.

From our basement’s floorplan, we get a total of 73.46 linear feet of walls. So that means that we needed, at least, 73.46 feet of pressure treated lumber and 146.92 feet of regular lumber (73.46 x 2 for the top and bottom plates). Adding an extra 10%, we get a total of 80.80 and 161.61 feet of lumber.

Now, based on your basement’s layout and personal preference, it is up to you to decide the length of the different pieces of lumber. Standard lengths are 8, 10, 12 and 16 feet, we got 8, 10 and 12 footers as they are easier to transport and we didn’t have any long enough walls to need 16-foot pieces (we have a 16.1-foot one but it was easier for us to frame it in two pieces).

To calculate the number of studs, you can multiply the 73.46 feet of walls x 12 inches per foot = 881.52 linear inches. If we then divide this number by 16 (or by 24 for a 24” layout) we get a total of 55 (or 37 studs for a 24” layout).

However, keep in mind that you need more than the studs every 16 or 24 inches. You need corner studs, door and window headers, sill plates and many cripple studs around them. You may also need to frame walls parallel to your floor joists for which you will need some blocking, etc., it all adds up really fast.

So for this project, we bought an extra 35% or 75 studs, not including the soffit, which you can calculate using the same method, but based on the length and depth of it.

STEP 2: BOTTOM PLATE BASEMENT FRAMING

Once you have decided on a basement/framing layout, the next step is to mark it on the slab using a chalk line.

These chalk lines are the ones you use as a guide to position the pressure treated bottom plates that will be used to align the walls. These pressure treated bottom plates must be anchored to the concrete. To do this, we used the powder actuated nail gun and the 3” drive pins with washers.

 

STEP 3: DIY BASEMENT WALL FRAMING

With the pressure treated plates anchored to the concrete slab, you should be able to start framing your walls.

To frame the first wall, first of all, cut the top and bottom plates to the correct length. You can use the pressure treated plates anchored to the concrete as a guide.

Then, start measuring from the edge of the top or bottom plate. Draw a mark at 1.5 inches, then at 16” and 17.5”, then at 32” and 33.5”, then at 48” and 49.5” etc., until you have covered the full length of the piece of lumber.

If your piece of lumber is, let’s say 55” long, then you will have a stud at 48”, but not one at 64” (piece is too short), so you would have to decide whether this wall is in a corner (and another wall is going to be attached to it) or not. Then, based on this, determine which one of the different options shown on the image would work for the specific wall.

 

Once you have the layout, it is just a matter of nailing the studs to the top and bottom plates, every 16” or 24” depending on the layout you are using. Keep in mind though, that based on your ceiling height you may need to cut the studs to the correct length.

For example, we bought 104 5/8” studs, however, our ceiling joists are at 105.5” (some a bit higher due to the concrete not being perfectly flat). So once you account for the thickness of the top and bottom plates (1.5” + 1.5”), the pressure treated plate anchored to the concrete (1.5”) and the void space of at least 1.5” (per our building permit) between the pressure treated plate and the wall’s bottom plate, there’s no way you can fit a 104 5/8” stud in your walls, they need to be cut.

If you do the math (105.5” minus all the others), you get 99.5”, which is the length we used for our studs.

Before you lift the walls up, it is useful to use the laser level. Align it with your bottom plates and mark your floor joists on the basement ceiling. Once you do this, it is just a matter of lifting the walls (using some wedges to get the top plate tight to the floor joists), aligning them with the marks of your floor joists and nailing them.

The other option is using a regular level as you nail the walls to the ceiling. This option is not very accurate in my opinion.

Once the walls are nailed to the joists,  you can add a few screws for extra strength.

Finally, drill some 1/4″ holes every 24″ to the wall’s bottom plate. Then use the framing square to align the wall’s bottom plate to the pressure treated bottom plate and use these holes to insert and nail the 6″ nails to the pressure treated plates.

Framing a Basement Wall Parallel to Joists

When framing a basement wall parallel to the floor joists, the problem you have is that there may not be anything to fasten the top plate of the wall to. To solve this problem, install some pieces of lumber, every 16” in between the two floor joist where the wall is supposed to go (as you can see in the previous picture, to the left of the window), then nail your top plate to these pieces.

 

 

Framing Around Basement Windows

Framing around basement windows is not a lot more difficult than framing a regular wall. You need to make more cuts (cripple studs, etc.), but other than that, you follow the exact same procedure.

The main difference is, that you need to determine where to start and end the window opening so that when you lift up the wall, it is both the correct size and aligned with the window.

To determine the correct height of the window opening, measure from one of the floor joists to the top and bottom of the window. You may need to use a level as a guide for an accurate reading.

 

Once you have the first measurement, you can subtract 3” (top plate and window header) + any desired distance between the window frame and the framing (to account for drywall, etc.). What you get is the length of the top cripple studs.

To determine the size of the bottom cripple studs, subtract the distance from the floor joist to the concrete slab to the second measurement. Then, subtract an extra 3” (bottom plate and window sill) + any desired distance between the window frame and the framing. On top of this, you need to subtract 1.5” (pressure treated plate) + void space between the pressure treated bottom plate and the wall bottom plate (usually between 1.5” & 4”). The result is the length of the bottom cripple studs.

To make sure your window opening will be aligned from side to side, position your top or bottom plate on the floor right under the window. Then, use a long enough level and position it on top of the top or bottom plate right where you want your window framing to end. Then, mark the lumber where the two side studs are supposed to go.

 

And that’s basically it, you should have a perfectly aligned window framing if you follow these steps.

Basement Soffit Framing

Unfortunately, basements always require soffits if you want to install drywall. There are always water pipes, sewer lines, HVAC ducting or even beams sticking out of the floor joists, there is no way to just drywall on top of them.

Fortunately, though, it is not that hard to work around this problem. It is time-consuming and you need more lumber than if you could just hang the drywall to the floor joists, but it is not the end of the world either.

There are two basic types of soffits: when there is a support wall (or half soffit?) and when there isn’t.

To frame the first type, which is the one we framed and can be seen in the pictures, you first nail a piece of lumber of the right size (2×4, 2×6, etc.) and length to the supporting wall, perpendicular to the wall studs.

Then, you need to cut as many L shaped supports as you need (one for every floor joist). As can be seen in the images, the L shaped supports are to hold another piece of lumber, parallel to the one you nailed to the wall on the previous step.

 

Using a level, you can nail the first 2 (on each end) L shaped supports to the corresponding floor joists, then you can nail the piece of lumber, parallel to the one you nailed to the wall. Once this piece of lumber is in place, you can install/nail the rest of the L shape supports.

As you install the L shape supports, you can also measure from the piece of lumber that is nailed to the wall to the one you just nailed to the L supports to determine the length of the studs. A good practice is to position these studs right next to the L shape supports. If these studs span more than 3’, you either need to add extra supports in the middle or use metal supports.

 

 

The second type of soffit is when there is no wall to nail to, so both sides of the soffit are fastened to the floor joists. The procedure is exactly the same, except that you need extra L shaped supports for both sides of the soffit. The same rule applies if your studs span more than 3’.

 

 

ROUGH PLUMBING AND ELECTRICAL INSTALLATION

As you can see in the different pictures, as we progressed with the framing, we also worked on the electrical and plumbing. This allowed us to move forward with the project while we waited a few weeks to get our building permit and our first plumbing (ground work) inspection. Right after that first inspection, we were able to go ahead and cover that big hole in the concrete, finish the framing, plumbing, electrical and be ready for the rough-in inspection.

 

*This post contains affiliate links