How to Create a Box Molding Wall: Step By Step Directions

If you have been wanting to create a box molding wall or walls this simple guide will step you through how to install box molding in no time! For more DIY projects be sure you get all my latest updates on Instagram @howwedo208! 

How to Create a Box Molding Wall

I love DIY projects that really elevate a room from basic to wow! I did this recently in the laundry room when I showed you how to wallpaper on a weekend and now I am doing it in the water closet by creating a box molding wall! Also if you’re searching for other similar ideas, box molding is often referred to as picture frame molding, so that’s another phrase you can include in your search.

I know that you are going to be amazed at your own room transformation project when you install box molding in your home! When you do, be sure to tag me on Instagram in your finished projects so I can see how amazing they turn out! #howwedoandyoucantoo 

Getting Materials

You will want to gather all your materials ahead of time online or at your local hardware store prior to starting your project. Be sure to have extra molding pieces to account for miscuts or pieces that are too short. I had to go back to get more and it can be frustrating to have to leave a project in the middle to go get more supplies. 

Supplies for Installing Box Molding

• Base cap molding (wood or PVC)
• Painter’s tape
• Pencil 
• Tape measure
• Stud finder
• Level
• 3 scrap pieces of wood the width of your spacing
• Brad nailer
• Nails
• Joint compound (if you are moving toilet paper holders)
• Wood Filler
• Caulking Gun
• Caulk (paintable)
• Baby Wipes (lots of baby wipes)
• Q-Tips
• Toothpick
• Good quality painting supplies

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Step by Step Guide to Installing Box Molding

The first step in your box molding project is to map out the template on your desired wall. Decide on:

• How many boxes do you want to create? (It helps to use painter’s tape and tape out box templates on the wall to get a good visual.)
• What sizes do you want your boxes? 
• What spacing do you want in between your boxes and the sides of the wall?

Once you decide on these things you are ready to get started! 

In my box molding wall project I wanted to have my box molding with 3 inch spacing from the walls, the ceiling, the baseboards, and in between each box. This spacing should all be equal. 

• After deciding on your spacing, it is helpful to create spacing blocks out of scrap wood. These should be the width of your desired spacing. In my case, I made mine 3 inches wide. This will help with the placement of the molding. 
• Measure how long each molding piece will be. You will want to use a miter saw or miter shears to make all your cuts. All cuts will be at a 45 degree angle. Cut one side of the piece at a 45 degree angle directed inward, and then cut the other side of your piece at a 45 degree angle going the other way but also directed inward.  All measurements are based on the outside edge of the pieces cut, not the smaller side or inside cut. 

• Use your laser level to determine if your wall corners and ceilings are plumb and level. Chances are they will not be. If they are pretty square, this spacing block method will be fairly quick and easy. If they are not square, mark plumb and level lines on your wall to know where to place your spacer block.
• If your walls and ceilings are not really level at all, instead of using this spacing block method, I recommend using a level, laser, and a pencil to first draw each box on the wall. Then when you’re ready to install the molding, you simply match up the edges with your outline.
• Place your spacing blocks in the bottom corner of the wall. One will be horizontal and the other will be vertical. This provides you the desired spacing to ensure the boards are at the right spot on the wall. 
• Place your first vertical molding right next to the space and using a brad nailer attach it at the bottom corner of the wall. 
• Slide your horizontal spacer up the wall about 6-8 inches and nail again. 
• Continue until you have attached your entire molding piece on the wall. 
• Now attach the bottom piece of trim of your box molding. Place this next to the spacer that is on the baseboard and position it right next to the molding you attached. The 45 degree angles should fit nicely together. If there is a little bit of spacing it can be fixed with wood filler at the end of the project. Nail the corner of the piece to hold it. 
• Continue to slide your spacer along the baseboard to ensure you keep the same spacing as you nail the molding to the wall. 
• Move your side spacer to the opposite side of the wall and attach the molding piece the same way you attached the other side molding piece. 

• Place the top box molding piece in between the two horizontal pieces. Use a level to make sure it is straight and nail into place with your brad nailer. 
• If you are doing a 3 box molding wall like I did, place your spacer on the top of the bottom molding box and use two side spacers to attach the bottom of your middle box. Ensure this piece is perfectly even and positioned. Once you double check to make sure it is level and even, nail it into place. 
• Next, move onto the very top molding box. I found it easiest to attach the sides first using the same method, then the top piece, and then the bottom. 
• Attach the sides to your middle molding box as you use the spacers and then attach the top of the middle molding box. 
• It is important to note that you can install the box molding pieces in any order that makes the most sense to you. I did this same box molding style trim in my girls’ bedroom, and I installed all the top and bottom horizontal box pieces along the wall first. And then I went back and installed all the vertical side pieces. Do whatever you prefer!
• If you are doing more than one wall the process is the same as above, but since the width of the wall is different than the back wall, just note the width of the boxes will be different so be sure to re-measure for other walls that you choose to do. 
• If you run into a light switch or a toilet paper holder you can choose to move these or go around them. With light switches, most often people choose to go around them. The nails will not be seen once the nail holes are filled.
• Now that all the moldings are on the wall it is time to fill nail holes, fill cracks, and gaps. 

How to create a box molding wall without seams 

It is totally normal when making a picture frame box molding wall for there to be some gapping in the seams. However, the gaps should be pretty small. If you have any large gaps I recommend cutting a new piece of molding. Use wood filler to fill in any gaps. It is tedious and messy, but worth every minute of effort. This is what gives your DIY project a super professional look. 

• I love using Dap Premium wood filler. I have found it to be the best. 

How to use Wood filler on Miter corners

• When you are using wood filler on mitered corners first overfill the gap with wood filler. 
• Once it is nice and full, take a baby wipe to help smooth it out. 
• If your wood pieces have lots of detail like mine did, use a Q-Tip to help clean it up further. 
• Use a toothpick in the corners to clean it up even more. Like I said it is tedious but really really worth it in the end. 
• If you are using flat pieces then you can use a putty knife. 

If you are a visual person, hop over to Instagram and watch my box molding highlight reel and I will show you how to do this like a professional. 

Caulking Your Box Molding Wall

Caulking your box molding wall is super important. This helps eliminate all the tiny gaps that are between the wall and the molding and creates a seamless finish.

To get started put the caulk tube in your caulking gun. Be sure you are using paint grade caulking if you choose to paint! Cut the tip of your caulk at a 45 degree angle. Use the metal piece of your caulking gun to remove anything in the caulk nozzle. Once your caulking gun is prepped and ready it is time to start caulking. 

• First squeeze a small bead of caulk along the area you want to seal with the angle portion of the nozzle. Move slowly along the gap as the bead of caulking comes out. It does not take a lot of caulking unless you have a big gap. The more caulking you use, the messier it will be. 
• Dip your finger in water and then smooth the bead of caulking out. Wipe all excess caulk off the wall and molding with a baby wipe. You will use a lot of baby wipes in this project.
• Continue to do this over all the pieces of molding. Be sure to caulk around the inside and outside of each piece. 

Caulking Tips

• The DAP Alex caulk line is my favorite.
• Be sure to release the pressure of the caulk on the caulking gun in between each bead of caulk or the caulk will continue to flow out because of the pressure. 
• Some people choose not to caulk what you don’t see. So if the molding is really low to the ground, the bottom outside trim piece may not be caulked since no one will see it. The same goes for the outside of the very top piece near the ceiling. 
• You can buy a caulk cap to place on your caulk in between uses to keep it from drying up. 
• If you are planning not to paint, tape off a line where you’ll be caulking with painters tape. This will help give you a nice crisp line when you are done. 
• When you are cutting the tip of the caulk, be sure to not cut a big hole if possible. 

Painting Box Molding

For the smoothest paint finish, I prefer to use my paint sprayer. It does require more prep, but the actual painting goes quickly and the finish is super smooth.

You can totally paint by hand if you don’t have access to a sprayer. Be sure to use good quality paint brushes on the molding, I really like this trim brush and this corner brush. And it’s helpful to mix this additive into your paint to help eliminate brush and roller marks. It also improves the flow and leveling factors. As always, use good quality paint.

Here’s a list of some of my favorite painting supplies.

Is creating box molding easy?

Box molding is easy, but it does take time and prep. I think the most time consuming part is cutting all of the molding pieces. 

The other time consuming part is the filing of holes and the caulking, but it is extremely worth it in the end! 

What happens if you hit an obstacle like a toilet paper roll holder or a light switch?

I had this same issue when I was doing my box molding wall in the water closet. I opted to move my toilet paper roll. Watch my Instagram highlight reel as to how I moved it and for the light switch I opted to go around it. 

There you have it! How to install a box molding wall! If you like video tutorials be sure to watch it over on Instagram in my highlight reel. Be sure to tag me on Instagram in your finished projects so I can see how amazing they turn out! #howwedoandyoucantoo