GRK Fasteners FAQ: What Contractors Ask When Time Is Short

There's something satisfying about getting a rush order to a job site before the inspector arrives. After years of this, I've learned which fastener questions actually matter. As a supply coordinator for a distributor that carries GRK fasteners, I handle the urgent calls - the ones where a contractor needs a specific screw today, not next week. This FAQ covers what I keep being asked, plus a few things I wish more buyers asked.

Questions this page answers

• Are GRK fasteners worth the money?
• Which GRK trim screw goes outside?
• Can the RSS 10 x 3-1/8 replace a lag bolt in a structural connection?
• What is the 1/2 x 8 in. lag thread screw eye?
• What is the GMTK tool box and why do people order it?
• What size drill bit do you need for a #8 machine screw?
• Should one screw do every job?

1. Are GRK fasteners actually worth the price?

Here's the thing: if you are throwing together a temporary brace that comes down in two weeks, a cheap screw will get you there. But for anything that has to stay put - trim, decking, structural connections, outdoor exposure - the GRK upcharge is easy to justify.

The star-drive is the biggest difference. It doesn't cam out like a Phillips when you are driving at an angle or high speed. The bit sits deep in the head, so you can seat the screw without burning out. That means fewer stripped heads, less cussing, and faster go-backs. Last quarter alone, my team processed 47 rush orders, and at least 10 of them started with someone using a rusty starred screwdriver bit on a new batch of GRK screws. Replace the bit, not the screw.

One more honest note: GRK screws are not magic. A dull bit or too much torque can still mess up a head. But in normal professional use, the consistency is real.

2. Which GRK screw should I use for exterior trim?

If you are installing window casings, corner boards, PVC trim, or anything outside with a clean profile, reach for GRK's Fin/Trim exterior trim head screws. That exact line - Fin/Trim exterior trim head screws - tells you most of it: the head is small, so it countersinks flush without crushing the surface.

Builders often ask why I don't tell them to use a deck screw for PVC trim. A coated deck screw has a larger head that can crack the edge of a thin trim board, and the threading isn't designed to pull trim tight to the framing without splitting. The Fin/Trim line also has a corrosion-resistant finish designed to stay invisible after priming and painting. If you get the brown or white coated version, you can even skip the paint touch-up on areas that are hard to reach.

3. Can GRK Fasteners' RSS 10 x 3-1/8 replace a lag bolt in a structural connection?

The short answer: in a lot of wood-to-wood framing connections, yes - if you follow the published specs. But I am not a structural engineer, so I can't tell you 'this connection is fine' over the phone. What I can tell you from the supply side is how the product works.

GRK Fasteners RSS screws - including the 10 x 3-1/8 version - are engineered as a replacement for traditional lag bolts and through-bolts in many cases. You get a sharp point and aggressive threads that pull the member tight, and the head has that star-drive recess for high torque. The published load tables and code reports are where the magic lives. If the table says the allowable shear is enough for your beam hanger or ledger, you can proceed.

The problem I see in emergencies: someone swaps in an RSS screw because they think 'structural' means 'use it for anything.' Not true. You still need minimum edge distances, end distances, and thread penetration. If you're not sure, that's the time to ask an engineer - not the guy who answers the phone faster. A quick 5-minute call with the spec sheet can save a failed inspection.

I have mixed feelings about structural screw replacements. On one hand, they're quicker, cleaner, and less likely to split wood than hauling out a lag wrench. On the other, they create an illusion that the connection is automatically code-compliant. It's not automatic. The spec sheet is your code guide.

4. What is the 1/2 x 8 in. lag thread screw eye?

Most people come across this one while browsing the GRK catalog and ask, 'Why does this giant eye bolt have a wood screw thread?' The 1/2 x 8 in. lag thread screw eye is for hanging or anchoring loads from wood members. You drive it into a beam or post the same way you would a lag screw, and you end up with a rated eye point for a chain, cable, or rope.

Its size is heavier than the typical eye screw. At 1/2-inch diameter and 8 inches long, this thing is meant for serious pull-out resistance. But don't eyeball it: GRK publishes the load values for eye screws too. The type of wood, thread depth, and grain direction all matter. If you can't find the spec sheet, don't hang anything you care about on it.

5. What is the GMTK tool box?

The GMTK tool box is one of those accessories that seems unnecessary until you've lost a star-drive bit at the far end of a framing job. It's a small kit, not a full box of tools. Inside, you'll find a selection of GRK's star-drive bits and a few installation helpers. Think of it as a refresh pack for your driver collection.

Why is it important? Star-drive only works well when the bit is fresh and matched to the screw size. A worn T-20 or T-25 bit can round out the recess, and then the screw is stuck halfway in. Contractors who keep a GMTK tool box on site tend to have fewer stripped screws and less downtime. It's cheap insurance compared to a re-do.

6. What size drill bit do I need for a #8 machine screw?

This question is in the list because it comes up whenever someone is organizing a hardware drawer. The answer depends on what you are trying to do.

If you are tapping new threads in metal for a #8-32 machine screw, use a #29 drill bit as your tap drill. If you are drilling a clearance hole so a #8 machine screw can pass through, use a #18 bit for a snug fit or #17 if you want more play.

But if you bought a #8 GRK wood screw and think you need a pilot hole bigger than a scratch, stop. That's not a machine screw. For most softwood applications, GRK's own thread design lets you drive directly without pre-drilling. In hardwood or near the end of a board, a small pilot bit can prevent splitting, but the pilot hole size is different from a machine-screw tap drill. When in doubt, test in scrap first.

7. Should one screw do every job?

If you only have one box of screws in the truck, you'll probably try. But 'multi-purpose' doesn't mean 'all-purpose.' GRK makes multi-purpose framing screws for general fastening, and those are great for a wide range of jobs. Yet they are not trim-head screws and not structural rated fasteners.

When a supplier tells you one screw can handle every connection, that's a red flag. The best vendor advice I ever got was from a sales guy who said, 'That application isn't our product; here's who makes a better fit.' He lost a small order and kept my account forever. I would rather be told 'this isn't the right one' than to find out later that a structural post was held by a deck screw.

So no, you don't need fourteen kinds of screws. But you do need the right three or four: trim, structural, multi-purpose, and maybe a specialty hanger when the job calls for it. That's the honest boundary of any fastener system.