What Size Nails for Crown Molding?

What Size Nails for Crown Molding?

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Crown molding installation tips and tricks are easy to find online. Reputable websites and popular blogs provide ample details on cutting techniques, measuring, mitering, and coping. On every list of materials required for installation is the word “nails,” often without any more details or clarifications.

How do you choose which nails to use? This article will discuss which nail types and sizes to choose when shopping for your crown molding supplies, special situations to consider, and common pitfalls to avoid.

What Size Nails Should You Use for Crown Molding?

There are a few factors regarding nail size that are important to consider, namely nail gauge and length. First, I’d like to highlight the main difference between two nail types you’ll commonly see in crown molding installation: brad and finish nails.

Nail Type: Brad Nails vs. Finish Nails

Both brad nails and finish nails are used in crown molding installation, but for different applications.

Brad nails are thinner than finish nails, and are not as strong. Brad nails are ideal for use in joining outer corners and installing a finish, or return. Finish nails are thicker and stronger than brad nails. They are used to attach the molding to the wall and ceiling.

1. Nail Gauge

The larger the gauge, the thinner the nail.

Brad nails are 18 gauge, or 0.05 inches thick. Finish nails recommended for crown molding are 15 or 16 gauge, or 0.07 or 0.06 inches thick, respectively. Typically, 16 gauge is sufficient, but in cases where the crown molding is particularly wide or heavy, 15 gauge may be more appropriate.

2. Nail Length

The most common finish nail length recommended for crown is 2 inches long. When shopping for finish nails, you can expect to find lengths such as 2d, 4d, etc. Historically, nails were sold in boxes of 100 and priced by pennyweight, or “d”. Today, the “d” is a modern-day denotation for length. A 6d nail is 2 inches long.

The general rule of thumb is that the finish nail should be triple the thickness of the item you are fastening. When attaching through a “soft” object (like a wall or ceiling) into a stud, the thickness of that barrier should be added to the length.

Brad nails used for adjoining outer corners and returns are between 1 inch (2d) and 1-1/2 inch (4d) long.

Things to Consider When Choosing Crown Molding Nail Gauge And Length

The standard thicknesses and lengths mentioned above are common sizes that will see you in an average crown molding installation. These guidelines may change based on your answer to one or more of the questions listed below.

1. Are Your Walls Made from Drywall or Plaster?

Drywall thickness is 1/2-inch, and may be up to 5/8-inch. Lath and plaster walls, however, can be up to one full inch in thickness. This thickness must be accounted for when choosing finish nail length, so in cases where a 6d nail would be suitable for drywall, an 8d nail would be better advised for plaster walls.

2. What Size and Thickness Crown Molding Are You Installing?

The average homeowner uses crown molding between 2 ½ and 6 inches in height, as that is the recommended range for design aesthetics on an 8-foot ceiling. You can expect the thickness of a 2-1/2 inch tall piece of molding to be 1/2-inch at the top and bottom nailing points. When using heights at 3 inches or taller, you may find that you need to increase your finish nail length to account for additional product thickness.

This is where the “3 times the material thickness” nail length rule comes in handy. While a 2 inch nail is sufficient for molding with ½-inch thickness, 2-3/4 inches is required for 3/4-thickness, and so on.

3. Are You Building Up Your Molding with Extra Trim?

In grand rooms, such as the dining or receiving room, you may want to add a little extra trim to make your crown stand out. This may include installing base or decorative molding at the points where your crown will come into contact with the ceiling or wall. The thickness of these trim pieces must also be added to the overall measurement when choosing your finish nail length.

What are the Risks of Using Too Small Nails to Attach Crown Molding?

Some installers prefer to use brad nails throughout the entirety of the installation. Wood molding can be quite heavy, and 18 gauge may not be sufficient to hold that weight. Using too small of a gauge can result in loss of adherence for molding sections. If all you have are brad nails and a brad nailer, using two nails side by side can counteract sagging trim.

For nails that are too short, it may only be a matter of time before the molding begins to fall. Wood contracts and expands over time, which will be enough to pull your beautiful trim away if not enough of the nail is embedded in the stud.

What Are the Risks of Using Too Large Nails to Attach Crown Molding?

Without pre-drilling (sometimes pre-drilling is advised for nailed installations), any gauge thicker than 15- or 16 gauge could split your wood. If the wood doesn’t split and installation is successful, the remaining nail holes will be larger and more obvious if they are not filled.

For nail lengths that are too long, it is possible to damage existing structures behind the wall or ceiling, such as pipes and electrical, especially if you miss the stud.

Can You Attach Crown Molding Without Nails?

While construction adhesive can be used temporarily to hold wood molding in place, it’s always advised to nail where possible. For very thin corner molding used in lieu of crown, or for very short sections used in small places like a powder room, the correct adhesive can ensure safe installation.

In cases where cost or manpower is a factor, it may not be possible to use wood. Lightweight, flexible polystyrene foam crown molding is a great product for installations where nails aren’t a possibility. The pieces are adhered with joint compound or painter’s caulk, making foam molding an ideal product for renters that want to elevate their spaces or homeowners with limited resources.


When investing your time and money in beautiful finish carpentry, use the right size and type of nail to ensure the longevity of your work. I have outlined the different types of nails recommended for crown molding installation, the best nail sizes to use, and what can happen if the nails you use aren’t the right size for the job.

This article has hopefully helped you gain confidence in choosing which nails to use in your next installation. You might also want to learn about the right size nails for quarter round and baseboard.