The Right Way to Add a Room to a Finished Basement

You may want to add a room to your basement without paying a lot of money for a professional to do all the work. Though it may not be a walk in the park, if you follow these 9 steps then you can install a room all by yourself with some determination and hard work.

1. Check Local Housing Codes

It will be important for you to check the local housing codes before you do anything else. Some HOAs, cities, and states have very specific criteria surrounding building codes. You should also hire an engineer who can take a look at your house and your house’s blueprints and they can tell you if building the room you are planning is possible, safe, and legal.

2. Gather Materials

Building a new room is a massive project and will require a lot of different materials. Below we’ve included a list of things you will need at some point in the project. You do not necessarily need to buy all of these materials all at once.

  • Lumber Boards

Most likely you will want to buy 2″ X 4″ boards. There are some cases where you may need to get slightly larger boards, like if you have 4″ pipes that will be running through the wall. How many boards you need will depend on how large the room you are making will be.

  • Stud-Framing Clips
  • Stud Finder
  • Plumb Bob
  • Nails/Screws
  • Concrete Nails (optional)
  • Hammer/Drill
  • Measuring Tape
  • Level
  • Electrical Cable
  • Wire Nuts
  • Wire Cutters
  • “New Work” Electrical Boxes
  • Outlet Covers
  • Light Switches
  • Light Switch Covers
  • Light Kit/s

Installing electrical points can be tricky. One thing you should be very aware of as you buy material is sizes. Make sure that all wires and pieces fit and are compatible with each other.

  • Insulation

Most likely you will want to buy fiberglass insulation that is 3 1/3″ deep and 15 1/4 ” wide with an R-value of 15. This is the most common and is inexpensive.

  • Drywall
  • Wall Texture (optional)
  • Primer (optional)
  • Paint (optional)
  • Wallpaper (optional)
  • Wallpaper Adhesive (optional)
  • Brush/Soft Cloth (optional)
  • Paint roller
  • Painters Plastic

The last six materials are all optional. Whether you need them or not will completely depend on how you want to decorate the walls. You may want to texture your walls or maybe not. If you do, you will need wall texture and a roller.

Painting your walls is a common choice, and if you decide to do so then you will need primer, paint, and something to paint will and something to protect the floor.

Maybe you want to wallpaper your walls. In that case, you would not need paint or primer at all. You may need some adhesive though, depending on the type of wallpaper and brush or soft cloth.

  • Sub-flooring
  • Flooring of choice
  • Tile Spacers/ Tile cutter/ Mortar/ Grout (optional)
  • Tack Strips (optional)

There are lots of different options for flooring. What you decide to use in your new room will depend on what the room will be used for and your personal preference. Your options will include hardwood, vinyl, laminate, carpet, or tile.

Of course, the sky is the limit here. I once had installed foam mats (similar to flooring in gyms or nice car garages) in a boys’ room that I thought worked out perfectly for its purpose. Really, you are only limited by your creativity.

The floor type that you choose may have some needed materials that other types won’t need. If you choose to install tile, then you will need tile spacers and the other materials listed with them. If you choose to install carpet then you will need tack strips.

3. Measure Out The Room

You will need to use a measuring tape to measure out the length of the walls that you desire on the ceiling. Using chalk or a pencil to mark on the ceiling where you want the wall.

You’ll need to use your stud finder to find the joists in the ceiling. Your new wall should either match up perfectly with a joist or should be perpendicular. You may need to adjust the placement of your wall.

Once you have marked the measurements on your ceiling you can use your Plumb Bob to make parallel marks on the floor. If your basement is already finished and there is flooring laid down you will need to remove the flooring where you want to add the new room.

Once the flooring is gone and you have made marks for your new wall you can install the plates on your wall.

4. Install Plates

The plates are the lumber boards that serve as anchors for your wall. The plates that run along the ceiling will be called the top plates and the plates on the floors are called the sole or sill plates.

Based on the desired length of your wall, you may need to make some cuts to your lumber board. You can use a hand saw for this, but an electric saw will be faster and more precise.

Using the marks you’ve measured out, lay your sole plates down. Be as precise as you can. Most likely your basement floor is concrete, so you will need to use concrete nails to install the sole plates.

You can then install your ceiling plates, which will be a similar process to installing the sole plates. You will probably not need to use concrete nails on your ceiling plates.

5. Install Studs

Wall studs are essential to supporting your wall. To install studs, use your measuring tape to make marks every 16″ on your ceiling plate. Once this is done, use your plumb bob to make parallel marks on the soleplate. You may need to install tacks or temporary nails to use your plumb bob.

Measure the height between the sole and ceiling plate and then cut the lumber boards that will be your studs to fit this length. Once they are cut, you can wedge them into their spots (you may need to use a mallet to help get them into place). Then use nails or screws to secure them into place.

Once you have secured all the studs into place, your wall frame is done. Go ahead and repeat steps 3 – 5 for any other walls you need to add.

6. Install Electrical Points

Adding electricity to your new room can easily be the most difficult part of this whole project and if you are unsure if you can do it then you may want to hire a professional.

First, you will need to drill holes in your studs that are around the height of where you want your outlets and switches. You will want these holes to be about 3/4″ in diameter.

After that things can get pretty complicated. To avoid any miscommunication I’ve added a video from Feasible Prepper. In the video, Eric goes in-depth and shows how he builds an interior wall and then adds electricity to it.

In the video, he builds his wall on the floor and then lifts it into place, which is possible to do. However, I’ve instructed you to do a different method which I believe is easier and doesn’t allow for as many measurement mistakes.

7. Install Insulation

For this step, you will want to wear a long sleeve shirt, long pants, gloves, a mask, and goggles. Insulation can irritate your skin and can easily get into your eyes and lungs.

You can easily measure out the length you need on the insulation and then cut it with a knife. You can also easily cut out notches for electrical boxes and pull some batting out to make room for wires.

After the batting has been installed, plastic should be used to cover it. Staple the batting and plastic to the plates every 12″.

8. Hang Drywall

Before you start hanging the drywall, you should cover any doorways and vents, so that dust does not spread throughout your house. You will want to wear gloves, goggles, and a mask while doing this step.

Most drywall comes in 4′ x 8′ pieces, so you may need to measure out the height of your wall and cut your drywall pieces to fit. Once you have to pieces cut, you can hang the first piece on the wall. It may be helpful to have someone help you do this since drywall can be heavy and you want it to lay flat as you screw it into place.

Screw the drywall into the plates and the studs. When laying each next piece make sure it is fitted snugly to the previous piece.

You may have to make special adjustments to your drywall for doorways, windows, and electrical boxes.

9. Texture, Prime, And Paint

Once the drywall is hung you can start to decorate your wall how you choose. The most common way is to paint it, but wallpapering is another very common way. Since painting is the most common way, that is the route I’ll go in these instructions.

Texturing is very common and you will probably want to go this route. The process is simple. You’ll simply need to buy a wall texture, which should come in a bucket and can be applied with a paint roller.

Once the texture has dried, you can go ahead and prime the walls. Then once the primer has dried, you can paint your walls.

10. Add Flooring

After the walls are done you can begin to add flooring. No matter what type of flooring you choose you are going to need some sort of subflooring.

You will most likely have to concrete adhesive and concrete nails to get your sub-flooring installed.

Once the sub-flooring is in place you can install the floor of your choice.

11. Add Fixtures

Once the flooring is in place, you are pretty much done. All you have to do now is install molding (if you want it), light switch covers, outlet covers, vent fixtures, and light fixtures.

Now you have a brand new room that you installed all by yourself. Congratulations!

Ricky Kesler

With all of the projects I've done over the years, you'd think that I work on my house full-time. But I actually enjoy other things like spending time outdoors and time with my family.

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