Fasteners for metal and wood

HOW TO SELECT THE RIGHT FASTENERS
There are many sizes and styles of nails and screws available. As construction materials and techniques evolve, fastener design keeps pace with the changing technology. Fastener needs vary from one project to another. Safety and life expectancy of a project can be extended or compromised based upon the fastener used. When selecting a fastener, be sure to determine what the materials are that are being joined, the total thickness of the material being joined, where the fasteners will be used and how many fasteners you will need for the project.
Determine what the materials are that are being joined.
This will establish whether to use a nail or screw and the type of nail or screw needed.
• Attaching to wood: hardwood, such as redwood and cedar: Stainless steel is the only recommended fastener for redwood and cedar. Softwood, such as pine or other untreated lumber: For greater holding power, use ring shank nails instead of smooth or spiral shank.
• Treated lumber: Chemicals used to prevent rotting and insect infestation may increase fastener corrosion. ACQ Resistant or outdoor coated and stainless steel fasteners carry a long term assurance against rust and corrosion when used with any treated lumber. Hot dipped galvanized fasteners are also approved for use with treated lumber.
• Composite lumber: Consists primarily of recycled plastic trash bags and waste wood fibers. Special fasteners have been developed to accomodate the unique characteristics of this material, including composite deck screws (decking screws).
• Attached to steel: Thicker steel may require a self drilling point whilst a sharp or self piercing point may be more appropriate for thinner steel.
 Determine the total thickness of the material being joined.
This will establish the length of the fastener needed. An example to determine this would be: 1/2" plywood to 1/2" plywood = total thickness of 1". Fastener length for any material-to-wood will be determined by the specific embedment requirement, although 3/4" to 1" will normally be required. The length for most nails is measured from the center of the bearing surface of the fastener (head) to the end of the point. Casing nails, finish nails, and brads are measured from the top of their head rather than beneath.
Determine where the fastener will be used.
Inside? Outside? High-moisture aea? This will establish whether or not a fastener with additional protection against corrosion and rust will be needed. Outdoor applications and other high-moisture environments will require a fastener specifically designed for these conditions.
Determine how many fasteners will be needed.
Roofing - estimate that 5 lbs of nails will apply 3 squares of shingles.