There are a couple of ways to fasten 2 x material to steel columns, headers and trailer beds. While there are several types and sizes, we want to cover our 1/4-20 x 2-3/4″ self driller with wings and it’s applications. A flat self driller with wings is prefect for attaching your 2 x material to steel. The wings ream out the 2x material and then snap off when they hit the steel and then the screw continues to drill and tap threads into the steel. These screws will work in steel ranging from .110 (just under 1/8″) to .375 (3/8″ ) If your steel is too thin, the wings won’t break off and you will ream out the steel. If your steel is too thick the screw will eventually bind up. You will want to use the correct bit tip, a # 3 Phillips tip and use high speed on the drill or an impact driver. The screw may start out a little wobbly in the wood but once it gets into the wood, it will support the screw better and then you can apply needed pressure to work through the steel.
Our flat head self driller for 2x to steel features a WAR ® coating that exceeds 1,000 hour salt spray resistance. This not only makes it a good choice for exterior use when necessary but it is compatible with pressure treated lumber you may be using on a trailer bed. The 1/4″-20 screw offers great pullout strength, 1,800 plus in 1/4″ steel and over 2,500 sheer in the same steel making a fastening that will hold up to heavy use.
While these screws are used in construction applications like 2 x 4 lumber to headers, many are being used in adding trailer boards to the trailer frame. Again, the coating makes them compatible with pressure treated lumber and a better choice for trailers that are obviously exposed to the elements. The larger diameter of the 1/4-20 will not only give you better holding power but can simply handle more load and vibration. So if you are looking for a heavy duty screw to fasten down trailer boards, these are a good bet as long as your steel meets minimum thickness.