What Size Nails Should You Use for Crown Molding?

The short version: gauge and length

Two numbers matter when you pick a nail: gauge (thickness) and length. A lower gauge number means a thicker nail. For crown molding, 15 gauge and 16 gauge finish nails are the usual choices because they are strong enough to hold a molding that wants to pull away from the wall and ceiling.

Length is the more important decision. A crown nail has to travel through the molding, through the drywall, and then into solid wood. If it stops short, it only grips drywall, and the molding will loosen or gap over time. Aim for a nail that reaches at least 3/4 inch into the framing behind the drywall.

Our own best nailer for crown molding page makes the same point: pick a nailer that handles nails long enough to reach framing, and leave small holes that are easy to fill.

How to work out the right nail length

You can figure out nail length with simple math instead of guessing. Add up what the nail must pass through, then add the grip you want in the framing.

Standard drywall is commonly 1/2 inch thick, but check your walls, because older homes and plaster ceilings can be thicker. Measure your molding at the point where the nail will go in, since crown is thicker near its edges than in the middle of the profile.

• Measure the molding thickness where the nail will enter.
• Add the drywall or plaster thickness (commonly 1/2 inch for drywall, more for plaster).
• Add at least 3/4 inch for grip in the stud, joist or top plate.
• Round up to the next nail length your nailer accepts.

Matching nails to your crown profile

Bigger crown weighs more and has more leverage trying to pull it off the wall, so it needs thicker, longer nails. Small, light profiles can use a finer nail and a shorter length. The table below gives general starting points. Always confirm the length against your own wall and molding thickness.

If you are unsure between two lengths, the longer nail usually holds better, as long as it will not hit anything hidden. Check for wiring and plumbing before you drive long nails into a wall or ceiling.

15 gauge or 16 gauge?

Fifteen gauge nails are thicker and hold heavy crown well. Sixteen gauge nails leave smaller holes, which means less filling and sanding, and they suit lighter crown and general trim. Both are reasonable for most rooms, so choose based on the size of your molding and how visible the nail holes will be.

We would steer you away from 18 gauge brads for large crown, because they may not hold. A thin brad can work for tacking small pieces or helping an edge stay in place, but it should not be the only thing carrying a big molding.

Make sure the nails match your tool. Angled finish nails are made for angled nailers, and straight nails are made for straight ones. Check your nailer's manual before buying a box.

What the nailers on our page accept

The pneumatic models we compare all take nails in the range most crown jobs call for. The Metabo HPT NT65MA4 is a 15 gauge angled nailer that accepts nails from 1-1/4 to 2-1/2 inches and weighs 4.2 lb. The Metabo HPT NT65M2S is a 16 gauge nailer for 1 to 2-1/2 inch nails and weighs 3.7 lb, the lowest weight among the five products we list.

The meite T64A is also a 16 gauge pneumatic nailer for 1-1/4 to 2-1/2 inch nails, at 3.86 lb. The Paslode 902400 is a 16 gauge cordless angled model at 4.5 lb, which is the highest weight of the five.

Weight matters because you hold the tool overhead while nailing the top edge of the crown. You can see all of these side by side on our crown molding nailer comparison, including which ones have an angled magazine for tight inside corners.

Where to place the nails

Nail placement affects how well the molding holds. Crown sits at an angle, so you usually drive nails in two places along each piece: near the top edge into the ceiling framing, and near the bottom edge into the wall studs.

Use a stud finder or tap along the wall to locate framing before you start. Mark the stud and joist locations lightly with a pencil so you can hit them as you work. Many installers also use construction adhesive or small nails near the ends for a tighter joint, but the main holding power comes from nails that reach wood.

• Nail the upper edge into the ceiling joist or top plate.
• Nail the lower edge into the wall stud.
• Keep nails away from the very end of a board to avoid splitting.
• Test your depth setting on scrap molding first so nail heads sit just below the surface.

Safety notes

Wear safety glasses every time you fire a nailer, because nails can ricochet or a fragment of wood can fly back. Hearing protection is a good idea too, especially with an air compressor running in a small room.

Keep your hands and body clear of the nose of the tool, and never point a nailer at anyone. Disconnect the air hose or remove the battery or fuel cell before clearing a jam or leaving the tool unattended.

Working overhead means working from a ladder or scaffold. Set it on level ground, keep three points of contact when you can, and do not overreach with a loaded nailer in your hand. Before nailing into a ceiling or wall, think about where wiring, pipes or ductwork might run, and check the area first.

Frequently asked questions

Can I use a brad nailer for crown molding?

A brad nailer drives thin 18 gauge nails, which may not hold large crown on their own. They are better for small, light profiles or for tacking pieces in place. For most crown, a 15 or 16 gauge finish nailer is the safer choice.

Do I need a different nail for MDF crown?

The same gauge and length rules apply. Test your depth setting on scrap first, because MDF can swell around a nail that is driven too deep. A no-mar tip on the nailer also helps protect the surface.

What if I cannot hit a stud?

Move the nail along the molding until you hit solid wood rather than relying on drywall alone. Use a stud finder and mark the framing first. Nails that only grip drywall tend to let the molding sag or gap.

Should I fill the nail holes?

Yes. Fill each hole with wood filler or caulk, let it dry, sand lightly, and then paint or stain. Smaller nails leave smaller holes, so 16 gauge usually needs a little less filling than 15 gauge.