Trim fastening comes down to one number: gauge. It decides how much the nail holds, how big a hole it leaves, and which gun in the van you reach for. Get it wrong and you either split a delicate return with a nail that was too heavy, or watch a baseboard creep off the wall because the nail was too light to hold it there. This guide covers the gauges we stock, how to pick a length, and the collation and coating details that decide whether the nails will actually run in your gun.
Gauge first: what each size is for
Gauge is an inverse measure — the higher the number, the thinner the nail. Four sizes cover essentially all finish carpentry, and each one exists because the one next to it fails at something.
| Gauge |
Best For |
Holding Power |
Hole Size |
| 15-gauge |
Base, casing, jambs |
Highest |
Needs filling |
| 16-gauge |
General trim, crown |
Strong |
Small, fills easily |
| 18-gauge brad |
Small profiles, returns |
Light |
Barely visible |
| 23-gauge pin |
Glue-ups, tiny beads |
Almost none |
Effectively invisible |
Two points the table cannot carry. The first is that 15 and 16-gauge are not simply large and small versions of each other. Most 15-gauge guns are angled, which lets the nose reach into a corner an inline 16-gauge gun cannot; 16-gauge straight guns are lighter and easier to run overhead all day. Many trim crews carry both for exactly that reason.
The second is that a 23-gauge pin is not a fastener in the structural sense at all. It has no head, and its job is to hold a glued part still while the adhesive cures. Treat a pinner as a clamp you can carry, and the results are excellent; treat it as a nailer and the trim will come off the wall.
15 and 16-gauge: the nails that hold trim to the wall
Baseboard, door casing, jamb extensions and anything carrying its own weight belong on 15 or 16-gauge finish nails. We stock both in the everyday lengths: 2-1/2 in. 15-gauge for thick base and jamb work, 1-1/2 in. 15-gauge for lighter runs, and the 1-1/2 in. and 2-1/2 in. 16-gauge for general trim.
Length is set by what the nail has to reach, not by the thickness of the trim. The working rule is that the nail should land at least an inch into solid framing after passing through the moulding and the drywall. On half-inch drywall with a half-inch base, a 2-inch nail is the shortest that reliably gets there; anything less is holding drywall paper. That is why baseboard pulls away from the wall between studs, and it is the most common fastening mistake in a trim-out.
Where the trim is heavier or the wall is out of plane, screws do what nails cannot — our interior trim guide covers the trim-head screw option and the base-to-casing relationship that decides how the two meet.
18-gauge brads and 23-gauge pins: the small stuff
Brads carry the profiles that a 16-gauge nail would split: shoe mould, quarter round, scribe pieces, cabinet trim and mitre returns. We stock them from 3/4 in. through 1-1/2 in. and 2 in., which covers everything from a cabinet return to a light casing.
Pins go a step further. A 3/4 in. 23-gauge pin or a 1-1/4 in. pin leaves a hole you will struggle to find after paint, which is exactly what you want on a stained bead or a delicate applied moulding. Pair it with glue every time.
Hand-driven nails still have a place. 8-penny casing nails suit repair work and one-off pieces where dragging a compressor in makes no sense, and vinyl-coated paneling nails are the correct fastener for thin panel stock where a finish nail would blow through.
Collation and angle: will it run in your gun
Buying the right gauge and the wrong collation is a wasted trip. Guns are built for a specific magazine angle and a specific collation medium, and the two do not mix.
Fifteen-gauge nails are typically angled, and the angle matters: we stock 34-degree and 25-degree strips, and a 34-degree gun will not accept a 25-degree strip. Sixteen-gauge runs either straight or at 20 degrees — the 2 in. 20-degree angled and the 2-1/2 in. straight collated are the two common formats. Check the gun before the order, not after.
Glue-collated strips leave less debris on the work than plastic collation, which matters when you are shooting overhead or into a finished room. Plastic collation is more tolerant of a damp site. Both are stocked across the finishing nails collection.
Where the fastener is holding sheet goods rather than trim — housewrap, felt, insulation facing, cabinet backs — a narrow-crown staple beats a brad, because the crown spans and holds material a single shank pulls straight through. The staples collection covers the crown widths and leg lengths for that work.
Coatings, and what Los Angeles actually needs
Most interior trim nails are bright or electrogalvanized steel, and for a conditioned interior that is the correct and cheapest answer. The coating question only becomes real when moisture is in play.
Electrogalvanized is a light coating for damp interior conditions — a bathroom, a laundry, a garage. Hot-dipped galvanized such as the 2-1/2 in. 15-gauge hot-galvanized is the exterior-grade choice for trim that sees weather. And where a nail sits in a coastal environment or in cedar or redwood, stainless finishing nails are the only option that will not bleed a rust stain through the finish.
That last point is worth taking seriously along the coast from Santa Monica to San Pedro, where salt air will find a bright nail in exterior trim within a season. It also applies to the naturally durable species covered in our guide to cedar and redwood lumber, whose tannins react with plain steel and stain the wood from the inside out.
Ordering for a trim-out
Buy by the box and by the job. A house trim-out typically runs one length of 15 or 16-gauge for base and casing, one shorter brad size for returns and shoe, and a small box of pins for glue-ups. Buying four lengths of everything means three of them go stale in the van.
Check the gun before the order goes in: gauge, angle and collation all have to match, and the strip that fits your partner's gun may not fit yours. Our note on choosing the right screws for carpentry covers the cases where a nail is the wrong tool entirely.
We deliver fasteners and moulding together across Los Angeles County. Send the profile list and the gun you are running and we will match the nails to it.
Frequently asked questions
What is the difference between a brad and a finish nail?
Gauge. A brad is 18-gauge and thinner, leaving a smaller hole and holding less; a finish nail is 15 or 16-gauge, heavier and with real holding power. Brads suit small profiles and returns, finish nails hold base and casing to the wall.
What gauge nail should I use for baseboard?
15 or 16-gauge, long enough to reach about an inch into framing after passing through the trim and the drywall. On typical half-inch drywall that means a 2 to 2-1/2 in. nail.
Can I use 18-gauge brads for baseboard?
Only for holding a piece while glue sets or on very light profiles. An 18-gauge brad does not have the shank diameter to hold a run of base against a wall that is not perfectly flat, and the base will creep away between studs.
What are 23-gauge pin nails used for?
Holding glued parts still while the adhesive cures, and fastening small applied mouldings where any visible hole would show. They have no head and almost no withdrawal resistance, so they are always used with glue.
Do I need angled or straight finish nails?
Whichever your gun takes. Fifteen-gauge is usually angled at 25 or 34 degrees and the two are not interchangeable; 16-gauge is commonly straight or 20-degree. Check the magazine before ordering a case.
Which nail coating should I use outside in LA?
Hot-dipped galvanized for general exterior trim, and stainless near the coast or in cedar and redwood, where plain steel will stain the wood and bleed through the finish.
