Which Size Of Screw Is Best Suited For The Installation Of Wood Decking?


Screws are better fastener options than nails in a decking procedure. This is because screws are easier to remove whenever maintenance is required. Additionally, screws don’t pop like nails when used for decking.

Screws are generally better suited for deck fasteners but not just any screw. Screws come in different sizes and types and as such require some form of discerning as to which will best do the deck fastening job. Best practice stipulates that the screw sinks into the material by one inch or deeper. Another factor that determines the size of the screw to be used is whether or not it will be used on framing members. Also, the amount of weight they would support is consequential.

Different sections of decking require different sizes of screws. Hence, we will look at these sections and discuss screw sizes that are better suited.

  1. Deck Framing

For this purpose, the rim joists are mostly connected to the posts with bolts. However, if a screw is deployed, it must be large diameter screws better known as lag screws. These types of screws should be at least half-inch in diameter. 

This is compulsory when they will be supporting the weight of the deck. As for the point, it should sink at least one and a half inches into the member of the framing which will be left stationary. From this, we can infer that the minimum length of a lag bolt (as befitting this task) must be 4 inches when it is to be attached to a 2-inch board.

For lateral joists that are often hung from the rim joist using a joist hanger, a 6-gauge 1-inch screw is the best option.

  1. Decking Railing and Stairs 

For decking railing and stairs, 8-gauge deck fasteners are the standard. Two-and-half inch is the ideal minimum length that can be used for holding deck boards to the joists. When it is required to provide extra holding power against load, a 3-inch screw is preferably used. 

 Some decking processes fall under specialty decking. Specialty decking procedures require different sorts of arrangements. One of such cases is the IPE decking, which is extremely hard. For such decking, 10-gauge screws typically possessing smaller heads that can be engulfed by the surface are better.

For attachment of railings to posts and stair treads to stringers, a 3-inch screw should be used and then two-and-half inch screw for attachment of railing balusters. Decking fascia and stair risers require a ¾-inch screw. 

This is because they are composited of materials at least 1-inch in size. However, if it is non-load bearing boards (suited for decorative purposes), a one and a half-inch screw is suitable.

Generally, the downside of using inappropriate screw sizes is that splitting may arise. 

It gets even better if the deck is pre-drilled before fitting, especially for boards that are susceptible to splitting. For improved results, you can close a bit size that will allow the threads of the screw to slide through the hole without any catching.


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