Metallics TXW1478 1/4-14 x 7/8 in. 5/16 Hex Head Self-Drilling Screws with Bonded Sealing Washer - #1 Drill Point - All-Weather - Each

The TXW1478 uses a #1 drill point, which is the lightest of the self-drilling point sizes and is meant for thin gauge sheet metal rather than structural steel. With a 1/4-14 thread and 7/8 inch length, total grip is short, so it suits attaching panel, flashing, or trim to light gauge metal. For heavier base steel you want a larger drill point number, not a #1.

The sealing washer is bonded to the screw head, so nothing extra to order. The washer measures 0.480 to 0.520 inch outside diameter and 0.030 to 0.050 inch thick, and it compresses under the hex head to make the weather-tight seal on roofing and siding panel laps.

That is what they are built for. The TXW1478 carries a zinc plus all-weather coating tested to ASTM B117 salt spray, and the bonded washer seals the hole against water. For exterior panel and flashing work on light gauge metal it is the intended use.

A 5/16 hex driver or socket. The head is hex drive, with a head width of 0.367 to 0.375 inch and 0.409 inch across the corners, and it stands 0.172 to 0.19 inch tall, so a standard 5/16 magnetic nut setter in a drill driver seats it fine.

Yes, and the specs are the ones a submittal reviewer looks for. Dimensions follow ASME B18.6.3-2010, threads follow SAE J78-2013, the steel is AISI 1016-1024, case hardness is Rockwell C32-40, and minimum torsional strength is 150 lb-in. The coating is tested to ASTM B117.

Metallics lists the TXW1478 as both Buy American compliant and ARRA compliant, which is what public-funded electrical and MRO work usually requires on fasteners. Country of origin is listed as multiple, so confirm the origin marking on the jar you receive if your specification requires a single named country.

No. The TXW1478 is a Type BSD self-drilling screw with a drill point on the tip, so it cuts its own hole and taps its own thread in one pass. One driver, one pass, no pilot drill, which is why these go up fast on panel work. Keep drill speed moderate so the point does not burn before it breaks through.

A plain hex washer head self-drilling screw clamps metal to metal with no gasket, fine for interior framing, strut, or hidden connections. The TXW1478 adds a rubber washer bonded under the 5/16 hex head that compresses to close the hole, so it is the one to use anywhere water can reach the fastener, like roof panel, siding, gutter, or exterior enclosure work.

They ship in a jar, with a 50 each minimum order. Total weight of that jar is listed at 0.75 lbs. Other sizes and quantities in the TXW series are available by request if 7/8 inch is not the length you need.