How to Choose the Right Finishing Box Size for Every Drywall Mud Application

With numerous finishing box sizes available on the shelves, it can be tricky to choose the right one for the job. Some may think size doesn’t matter, but the truth is that choosing the correct finishing box size plays a significant role in achieving a smooth and even drywall finish. We’ll break down the most common finishing box sizes to help you choose the right box for your next project. 

What is a Finishing Box? 

A drywall finishing box, also known as a flat box, is an automatic taping tool designed to apply joint compound (or drywall mud) smoothly and consistently over large surfaces in a single pass. It can be attached to a universal flat box handle to provide added reach and control when finishing flat wall and ceiling joints. Popular brands include Columbia, Level 5, TapeTech, TapePro, Asgard, DeWalt, and Drywall Master, offering a variety of sizes and options to choose from. 

What are the Common Finishing Box Sizes? 

5.5” & 6” Finishing Box

These small and compact finishing boxes are mostly used for tight spaces and detail work. They’re ideal for finishing around doors, windows, and narrow seams where larger boxes may be difficult to maneuver. A popular choice is the 5.5” Drywall Master High-Capacity Flat Finishing Box, which allows you to run the box longer in-between refills due to its increased mud capacity.  

7” Finishing Box

This is the most common size used for bed coats, which is the first coat of mud applied over taped joints. It offers an ideal balance of coverage and control, making it a popular choice among drywall finishers. One of many notable boxes is the 7” DeWalt Flat Box, which features a five-setting adjustable crown dial to dispense the precise amount of mud onto the wall. 

8” Finishing Box

This size offers slightly wider than the 7” coverage, making it a popular middle-ground option and is also a popular choice for applying the first coat of joint compound. A standout from this size is the 8” Columbia Inside Track Fat Boy Finishing Box, as it features a manual sweeping grip for tight spaces when you can’t use a box handle. 

10” Finishing Box

This size is commonly used for the finishing coat, where it smooths and feathers the joint compound after the initial bed coat. We recommend checking out the 10" Level5 MEGA Flat Box, which can hold up to 30% more joint compound than other boxes. Though it becomes heavier and bulkier when full, it reduces a good number of trips going back and forth to the loading pump. 

12” Finishing Box

The 12” finishing box is ideal for applying wider skim coats and final finishes. A solid choice under this category is the 12” TapeTech EasyClean Finishing Box which contains a pivoting axle that helps compensate when the drywall or sheetrock on one side of the joint is higher than the other. It also has an EasyRoll Wheel system that allows you to expertly finish all types of outside corner bead up to two times faster than finishing by hand. 

14” & 15” Finishing Box

The wider the better, right? These sizes are mainly used for Level 5 finishes and full skim coating. A popular choice for these sizes is the 14" TapePro Booster Auto Flat Box. It features a spring-loaded pressure plate that helps force joint compounds out of the box which is advantageous for out of position or difficult to reach areas. 

Where Can I Buy Finishing Boxes? 

Shop various finishing boxes at CSR Building Supplies from trusted brands like Columbia, Level 5, TapeTech and more! We offer models of every size that you can check out in-store and our experienced staff members can help you choose the right box for you. We also offer fast and reliable shipping worldwide, so you can get ready-to-go finishing boxes shipped right to your doorstep. 

Resources: 

https://drywallmastertools.com/product/standard-axle-flat-finishing-box/ 

https://www.level5tools.com/blog/what-is-a-drywall-flat-box-how-do-drywall-flat-boxes-work