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Exterior Fasteners

Choosing The Proper Exterior Fastener




I’m a single mom and trying to keep up a house alone can be tough work.  I have several porch boards that need to be replaced.  I’m confident on measuring and cutting the boards but am confused about all the different types and finishes.

Please help!  Carla G.


Exterior fasteners can be confusing especially when you see all of the varieties available at the hardware store.  Basically nail finish can be categorized into two categories; those that are corrosion resistant and those that are not.   It’s important to choose the correct nail finish especially when working outdoors.  Choosing the wrong finish or type of fastener is a common problem I see with DIYers.

For your porch boards situation you want to make sure you use ring shank nails that are rated for exterior use.  You may also want to consider using exterior grade screws .  Here’s a quick lesson on fastener finish:

Non-corrosion resistant nails:

Commonly referred to as “bright” nails.  Bright nails are steel and have no finish and are commonly used for framing and interior trim applications.  If used outdoors they will rust, streak and eventually corrode away.

Corrosion resistant nails

Corrosion resistant or exterior grade fasteners [nails] come in different finishes, they are all rated for exterior use some are better than others.

Examples of exterior fastener finishes are:


A common way of making nails corrosion-resistant is to coat them with zinc.  Most galvanized nails are electro galvanized.  This is a process where the nail is plated with zinc.  E.G. nails are not as corrosion-resistant as hot-dipped nails.

Hot Dipped Galvanized:

Hot-dipped (H.D.) nails have been galvanized by dipping them in molten zinc.  H.D. nails have a better corrosion resistance than electro galvanized.

Stainless Steel:

Stainless fasteners are expensive, but can be used just about anywhere.   Out of all the nail finishes stainless steel nails are the best exterior finish. Not all stainless steel is the same corrosive environments or materials, such as ocean salt air, water or preservative treated wood, can compromise the performance of even galvanized nails.

Most of the stainless steel nails sold in lumberyards in my area are graded as 300 series or 410 stainless steel.  Of these, the 300 series of stainless steels is most popular.  These stainless nails  alloys contain about 18% chromium and 8% nickel for good corrosion resistance, but make them non-magnetic and non-heat-treatable.

The best choice when near the ocean would be to use 316 stainless steel which has molybdenum added to the finish  which increases it’s corrosion resistance, strength, and cost


Copper nails do not rust and are mostly used for copper applications like copper roofing, gutter and ornamental application.

Corrosion resistant screws:

In some applications using a screw is better  than a nail.  Screws have better holding ability and can be the difference between a porch that squeaks and one that does not.  Decking material like composite decking should be screwed.

305 Stainless Steel Screws with a Type 17 cutter point are perfect for any outdoor project, especially decking.  Many times I will use the smaller head screw to make them less visible.  Stainless steel screws  approved for  treated woods (ACQ®) and are recommended when using acidic woods like Western Red Cedar or Redwood and are also a good choice for use with composite decking materials.

A Type 17 point can generally be driven into pressure treated woods without countersinking. A countersink is recommended when using composite deck materials because of density found with many of these materials.  Countersinking and pre-drilling are also recommended for hard woods like Mahogany and Ipe.  Choosing a square drive screw will also allow make your life easier and produce less wasted screws and driver tips.

Good luck.

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