Whenever a project is going to be part of the outside of a house in the weather, it’s a good idea to make sure to use exterior screws and wood finish. Whenever you are choosing screws, there are three things you need to consider:
They are corrosion resistance, appearance and strength. Most wood screws are made with ferrous metal or non ferrous metal. Ferrous materials are iron based.
Although they are inexpensive and strong, ferrous screws will easily rust when exposed to the outside weather elements, particularly in places with lots of moisture. There is enough moisture in the wood itself that can cause regular steel screws to rust.
Typically, the choices you will have are brass plated screws or zinc plated screws. The more common one is zinc. Both brass plated and zinc plated screws work very well for indoor projects.
Interior screws get plated with a very thin coating that is very easy to scratch off or wear down. After this takes place, they will inevitably start to rust.
This is especially true when they are used outdoors. However, not that long ago, there were a couple of new steel screws that are rust resistant that were released into the market. They do have high resistance against corrosion. However, they are not much more expensive than regular zinc plated screws.
One of the new screws just looks like it is a zinc plated screw. It is a steel screw that has a zinc-chromate coating, like a deck screw (another exterior screw). They have a clear coating of rust resistant material.
I use those screws when I build porch swings and other kinds of furniture. None of my customers have ever come back and told me that some of the screws on their outdoor furniture is rusting.
Another outdoor screw that has been introduced in the marketplace is made out of steel as well. However, it has a generous amount of coatings made from rust proof metals. In case you are wondering where to get these screws, McFeeley’s carries them.
The two screws that I have discussed are rated as screws that can hold up in a wet environment. This is due to the fact that they’ve been placed inside a moisture chamber and have been sprayed using a 5 percent salt solution for at least 500 hours.
Regular zinc screws only lasts approximately 100 hours before rust starts to appear. There’s really no comparison to these screws for outdoor use.