What length decking screws should I use?

Whiteagle

I am building an outdoor deck. I have purchased merbau decking boards 140mm x 19mm thick. I am wondering what size screws to use.

At various websites I have seen recomendations: 12g x 50mm, 10G x 60mm, 10g x 65mm. Websites often say this is the minimum recommendation which makes you wonder what is the ideal size?

I will use stainless steel although there is some suggestions to use marine grade. I am 7km from the ocean.

EricL

Hello @Whiteagle

I suggest using 10g x 65mm decking screws. This is the common size used for decking panels. When you think of how it is embedded in the timber 20mm will be buried into the decking panel and the remaining 45mm will be drilled into the decking frame. So 2/3 of the function of the screw is to hold the decking panel in place. If you happen to be in an area where strong storms pass regularly, then it would be worth putting in larger screws. Just remember to drill pilot holes for the screws to prevent splitting the decking panel.

Using stainless steel screws is always a plus. They provide excellent durability thanks to high vibration resistance that makes it difficult to unscrew them. It's low maintenance due to stainless steels resistance to corrosion

If you need further assistance, please let us know.

Eric