The Mod Truss Screw #8x1/2″ combines self-drilling TEK point technology with a modified truss head design that solves two critical problems in metal fastening: eliminating pilot holes and preventing material pull-through. Worth it for metal framing contractors who need reliable fastening in light-gauge steel. The TEK point drills through 20-12 gauge steel, while the low-profile 0.102-inch head provides a semi-flush finish.
Skip it if you’re just hanging drywall on wood studs. Standard drywall screws cost less and work fine for basic applications.
Technical Specifications That Matter
This screw meets multiple ASTM standards including C 1513 for cold-formed steel framing, A 510 for general carbon steel wire rods, and F1941 for electrodeposited coatings — certifications that actually mean something when you’re fastening structural connections.
| Specification | Value | Source |
|---|---|---|
| Diameter | #8 | manufacturer |
| Length | 1/2 inch (12.7 mm) | manufacturer |
| Material | Steel | manufacturer |
| Head Diameter | 0.384-0.450 inches | manufacturer |
| Head Height | 0.102 inch | manufacturer |
| Drive Type | Phillips #2 | manufacturer |
| Thread Type | 15-18 TPI | manufacturer |
| Tension Load | 285-550 lbs | tested |
| Shear Load | 829-1096 lbs | tested |
| Suitable Gauge | 20-12 gauge steel | manufacturer |
The tension load rating of 285-550 pounds and shear load rating of 829-1096 pounds put these screws in the right range for metal lath attachment and light structural connections. Those aren’t just marketing numbers — they’re based on ASTM testing protocols.
Self-Drilling Performance and Installation
The #2 drill point requires 2,500-3,000 RPM for proper penetration — run your drill too slow and you’ll burn out the tip before it cuts through. Keep the driver aligned with the screw axis to ensure the drill point engages and cuts correctly without slipping. Cocked angles cause the TEK point to wander and potentially strip out.
These work better than sharp point lath screws on heavier gauge metal because the TEK point actually drills its own hole rather than trying to force through. Sharp points might seem faster on thin material, but they require more force and tend to deform the metal around the hole.
The modified truss head distributes load over a wider area than standard pan heads, preventing material pull-through when you’re fastening thin metal lath or light-gauge framing. That wider bearing surface matters when you’re working with materials that can tear around standard screw heads.
Common Applications and Pack Sizes
Primary uses include fastening light-gauge sheet metal, attaching metal lath to studs in stucco applications, HVAC ductwork assembly, cabinetry where low-profile heads are required, and general construction including awnings, door frames, and gutters.
Available in bulk packages ranging from 100-count jars up to 5,000-count master cartons, with common sizes including 269-count boxes, 510-count packages, and 1,345-count boxes. Buy the big boxes if you’re doing production work — the per-screw cost drops significantly.
Zinc Plating Limitations
The zinc plating provides basic corrosion resistance for interior and limited exterior applications. Don’t expect miracles from zinc plating in Montana’s freeze-thaw cycles. It’ll handle dry interior work fine, but for exposed exterior applications or anywhere moisture collects, you’ll want stainless steel or a heavier coating system.
Compared to hex head TEK screws, these modified truss heads offer lower profile and better aesthetics for visible applications, though hex heads deliver higher torque capacity for heavy-duty work. Choose based on whether appearance or brute strength matters more for your application.
FAQ
Q: Can these drill through wood studs or just metal?
They’re designed for metal-to-metal and metal-to-wood fastening, though wood may require pre-drilling depending on hardness. The TEK point is optimized for cutting metal, not boring through lumber. For wood-to-wood connections, stick with regular wood screws.
Q: What’s the actual difference between these and regular drywall screws?
The self-drilling TEK point eliminates pre-drilling in metal studs, and the modified truss head provides significantly more bearing surface than a bugle head drywall screw. Drywall screws rely on the gypsum to hold them in place — these are designed to bite into steel.
Q: How thick of metal can these actually penetrate?
They’re rated for 20-12 gauge steel. Anything thicker than 12 gauge and you’ll either burn out the drill point or need to step up to a larger TEK screw with a more aggressive drill point.
Q: Do I need a special driver bit?
Standard Phillips #2 driver works fine — the Phillips drive reduces cam-out compared to slotted drives. Just make sure your drill can hit 2,500-3,000 RPM for optimal drilling performance.
Q: Are these the same as K-lath screws?
Yes, modified truss head screws are also known as lath screws — the wider head is ideal for thin materials like metal lath. Different manufacturers use different names for essentially the same design.
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