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How To Properly Use a Drywall Flat Box on Walls

How To Properly Use a Drywall Flat Box on Walls

Home contractors and renovators always need to stay current with all the tricks of the trade. For some, that may mean knowing the market and understanding how to gain more clientele. For others, it may mean discovering new tricks to use equipment and tools in a certain way to perfect their craft. For instance, learning how to use specific drywalling tools will ensure the final product appears more professional and lasts longer. To that end, here’s how to properly use a drywall flat box on walls.

What Is a Drywall Flat Box?

If you’ve been in the business for a while, you know that a drywall flat box is an automatic taping tool. The tool simultaneously applies the joint compound to the wall while feathering the edges of your seam to the crown. Drywall flat boxes come in a variety of sizes with most manufacturers making 7", 10", 12", and 14”. Feathering usually happens during the drywall finishing level five. It can occur in levels four and three, but this is not as common.

Many seasoned contractors will use a larger taping knife for the feathering technique; a drywall flat box does this task for them. Instead of having to do this process in multiple steps, it can happen in one. Drywall flat boxes help ensure smooth finishes and consistent results while also making the job quicker and less stressful on your body. Automatic taping tools make the job easier and more efficient, so it would be in your best interest to invest in them.

How Does It Work?

Like all drywall finishing tools, there is a process to working with a drywall flat box. The process requires multiple steps, and it’s important to follow each one precisely. Deviating from the guidelines could result in an unsatisfactory outcome.


Prepare your compound before you begin loading up any taping tool. The key to a good compound mixture is to use the right amount of water. Don’t add too much because then the compound will become too liquid, and don’t add too little because then the mixture will be too thick. Have a bucket of water and a rag or sponge close by. Let the sponge soak up as much water as possible, then squeeze it out into the compound.

This helps control the amount of water you add, allowing you to monitor the mixture more carefully. Consider using a drywall mixing paddle to make the job easier. The paddle will help you achieve the desired texture for the mud.

Operate the Flat Box

Next, locate the compound pump and filler attachment on the tool to fill the box with the joint compound. Remember that you only need to fill the box with enough compound to cover the wall you’re taping. Overflowing this system makes the job messier than it needs to be.

After filling the joint compound through the front opening, attach the handle and get ready to start maneuvering it. Maintain a good grip on the flat box before proceeding to use it on the wall.

You will use the handle to control the flat box when you start to press it against the wall or ceiling. The power of this tool comes from you, the user, so make sure you keep the handle steady. The tool also features a pinched brake that locks the head in place so that it doesn't move. Release the brake to swivel the handle freely.

Load It Up

As you pump the compound into the flat box, move it side to side to achieve an even fill throughout the tool. Carry the flat box between the box and top of the handle to maintain control of the equipment. Never carry the tool by the brake; it’s top heavy, and you might lose control of the flat box. This also creates unnecessary wear and tear on the brake.

As you get ready to use the tool, you’ll likely notice that there is butt-boarding on your drywall job. This means there are recessed floating joints that are structurally superior.

Start from the bottom and work your way up when operating this device. This is easier when working with vertical seams because you can easily start from the bottom and pull off from the top down. When you reach the halfway point, start at the top and pull down until you reach the endpoint of the first taping.

Fix the Issues

It’s not uncommon to see small bubbles and pits in the mud after the first application. This often happens when you’re running your flat box. Make it a habit to run the box twice to solve the problem. We refer to this as chasing or tracing.

Make sure the bubbles and pits are gone before you move on to the next butt joint. When fixing bubbles, start at the top and run the tool down to eliminate those errors. Any problems that may develop are typically easy to resolve, especially when you use the TapeTech taping tools from Timothy’s Toolbox.

Run It Across

Press the flat box against the next butt joint and run it straight across the joint. Keep your body at an angle to ensure you’re the one leading the tool, not the other way around. Try to avoid running the flat box straight across the entire joint.

Stop after you have finished roughly 3/4 of the wall and switch positions. Apply the tool to the corner edge and run it in the opposite direction to meet the ending of the first taping. Again, there will likely be a few bubbles and pits, so you’ll need to apply a second coat.

You want to eliminate lap marks that go into the butt joint. Let go of the brake and move the flat box forward. As you get close to the edge, pull the brake and lift off so that there are no lap marks.

Knowing about the latest gadgets and how to use them properly is the key to a successful project. Understanding the ins and outs of how to use a drywall flat box will improve the efficiency with which you are able to complete the job and the quality of the final product. For more information, visit our website and speak to the experts at Timothy’s Toolbox.

How To Properly Use a Drywall Flat Box on Walls
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