The fasteners you choose for your decking has a direct impact on stability and longevity. Whenever exposure to water is expected, a careful approach must be taken when choosing your materials. This is even truer of marine environments, which not only have the challenge of water, but can also have the corrosiveness of salt. Choose the wrong fasteners and you may end up with rust, pitting or total hardware failure.
Metal Fasteners for Marine Decking
A fastener is a broad term given to any type of hardware used in construction - such as screws, bolts, nuts, washers, rivets and ties. All of these styles of fasteners come in different metals and finishes.
General knowledge of dock and deck construction will give you insight into what style of fasteners you need, but figuring out what metal hardware you should choose isn't always as straightforward.
Understanding corrosion resistance levels will help you to pick the right product.
Fasteners are typically broken down into four categories:
Low corrosion resistant fasteners are those made of phosphates, clear and yellow zinc, electrocoat, and 410 stainless steel. It's best to avoid these fasteners in marine environments.
Mechanically galvanized steel, hot-dipped galvanized steel and fasteners with double-barrier coating have a medium resistance level. With careful use they can be successful in marine decking, but High or Severe category fasteners are still recommended by marine contractors and professionals.
High-resistance fasteners include 304 and 305 stainless steel. These are a reliable and useful choice for general marine decking. If your deck isn't made of wood and won't have direct water exposure, you may do well with grade 304.
For maximum protection you'll want to look for hot-dipped galvanized steel with a class C rating, 316 stainless steel, copper, and silicon bronze. Grade 316 stainless steel is most often used and works well with all types of decking materials.
Bronze hardware is the most popular fastener type for underwater use while 316 stainless steel is recommended for above-water applications, making it ideal for decking.
Also Consider the Decking Materials
It's important to note that the decking materials you're using can have an effect on your metal fasteners. Certain materials, such as Western Red Cedar and other woods, have corrosive properties of their own which can exacerbate wear-and-tear when coupled with marine conditions.
When using a corrosive material you will want to choose a fastener that has high corrosion resistance. If you're building a marine dock complete with wood decking, going with 316 stainless steel should be considered a necessity rather than a luxury.
If you're using a composite decking product, you can look specifically for fasteners made for composites. A composite marine deck will perform well with Simpson Strong-Tie composite deck screws.
Stainless Steel Fasteners for Marine Decking
Stainless steel fasteners are the preferred choice by many expert deck builders when it comes to marine docks. As mentioned, 304 and 305 stainless steel are considered to have high corrosion resistance while grade 316 is often viewed as being the best option.
Grade 316 stainless steel has higher resistance to pitting and a specific type of corrosion called crevice corrosion. Crevice corrosion occurs when the fastener is surrounded by moisture-retaining materials but there is a lack of oxygen exchange. This happens more often in salt water settings than freshwater due to the natural chlorine in the salt water.
The use of 316 stainless steel and the proper sealing of the fastener holes on the deck will help prevent issues with crevice corrosion. Keep in mind that part of marine deck maintenance it to check fasteners for corrosion and replace if any damage is found. Starting with the right kind of hardware from the get go, however, is always your best and most responsible bet.
For more information on marine decking materials and fastener options, contact a marine construction representative at Pine River Group.