Trim Head Screws

All About Trim Head Screws

Trim Head Screws are one of the best-kept secrets of the Pros in our industry.

Although we have been selling them for 40 years here at McFeelys we are amazed at the number of customers that are new to them. Trim heads are #7 and #9 body with fine threads and a flat top head smaller than a standard flathead. They are usually sunk beneath the surface and finished with filler in trim work.  Like any fastener, they work best for the intended application.  Generally, we recommend using them in any application where a finish nail would be appropriate.  Imagine having a small diameter screw that would let you pull a joint tight! Because of the smaller head, the #1 square drive is the preferred recess; a Phillips would not work.  Torx is also a good choice.

Trim heads are great for instaling trim.  In softwoods, they will power right through the trim, drywall, and into the stud.  Hardwoods usually require pre-drilling to prevent splitting and ease the amount of torque required to set the screw.  Softwoods should even be pre-drilled; if you do not, there is always a troublesome burr or chip on the edge that prevents your filler from binding.  Finding the proper countersink for trim heads was always problematic because the proper size pilot was always 3/8 in.  diameter countersink, which was way too large for the screw.  Other 1/4 in.  Countersinks only had pilots that were too small.  We solved the problem: we worked with a US manufacturer to develop a specially designed heat-treated 1/4 in.  countersink with 1/8 in.  pilot. This works well for all of our trim head screws.  Generally, you will drill the first piece and let the screw do the work on the second piece.

Here's some important tips and a word of caution: you may never have a 100% success rate driving trim heads on a given job requiring many screws.  Trim head's small head and recess do not allow much error.  There is not much material to support the driver bit.  All of our steel trim heads are heat-treated steel, but you can still break the head in high torque situations, such as driving a three-inch screw into an oak stair tread.  The #1 recess is more sensitive to being driven off a 90-degree axis. Once you get off center and start to spin, your best bet for success is to remove it (while you still can!) and try driving another.  You may need to open up your pilot hole or lubricate with beeswax screw lube.

Besides trim, consider these screws for a few of these applications:

Fixing squeaky hardwood floors

You'll find that 1-5/8 in.  or 2-1/4 in.  can secure the hardwood to the subfloor without making a huge, obvious hole.  The smaller the hole, the easier it will be to hide.  Match the color as close as possible (lighter is better than darker), and you can even draw in grain to break up the line.

Extending Jambs

Use special 3-1/2 in.  and 4-1/2 in.  screws to add jamb extensions for thicker walls.  Drive right through the edge; if careful, the reveal on your trim can cover the hole.  No patching is better...right?

Stairs

Trim heads can work great for attaching risers and tread to stairs when used with a good construction adhesive.  They can also be used to toe-screw balusters in the right application.  As with most fastener uses, check with your local code enforcement official. Trim Screws in Torx, different colors, sizes, and lengths.

Decking

Regular steel trim head screws usually have a fine thread and do not offer appropriate withdrawal resistance for decking.  Smaller heads will pull through softer woods and composites.  Ask yourself if you would put down your deck with a finish nail.  Of course not! In most cases, with the exceptions noted below, trim heads are just not the best choice for decking.

Some harder composites and tropical hardwoods can use trim heads.  In these cases, you will use a stainless trim head that will have a deep wood tread like a standard decking screw.  Care must be given because stainless is softer than hardened steel.  Recesses are more prone to strip, and the thin #7 or #8 may not have the torsional strength to be driven to the correct depth.  Care must be given to drill the correct pilot and/or clearance hole.  Fastcap has a tool for that.

Match screw colors to your premium composite, PVC, or encapsulated decking material with this guide.  You will have a choice of 305 and 316 Stainless Steel or coated screws designed for outdoor use.

Installing Window and Doors

Straight through the jamb, shim, and into the jack studs.  With proper placement, they're easy to hide.  Remember to use corrosion-resistant screws such as our No-Co-Rode plated or stainless where needed.