Choosing the Right Fastener: Nails and Screws

There are a few question you need to ask yourself before you go shopping to determine which type of fastener you need.

• What materials need to be joined? Wood, metal and masonry all require different fasteners.
  
  
• What is the thickness of the material to be joined? For a secure connection the fastener must be the correct length.
  
  
• What weight or strength requirements are there? From framing a house to hanging a picture, there's a fastener for the job.
  
  
• How permanent will the connection be? If the work will be disassembled at some point, use a screw.
  
  
• Will the work be indoors or outdoors? There are specific fasteners for both types of applications.
  
  

The nail has been around for thousands of years. The first versions were heat-forged. When machinery entered the picture, they were cut from sheets of metal. Today, most nails are drawn and cut from rolls of wire. Here are some things to consider when selecting nails:

Size

• Nails are sold by weight or length.
  
  
• Wood nails are measured, or sized, according to length. This is expressed by the letter "d" (called penny). The symbol is English, signifying a pound in weight, related to the weight in pounds of 1000 nails. Sizes run from 2d (2-penny/1" long) to 60d.
  
  
• Nails generally are 1" to 6" in length, usually getting thicker as they get longer.
  
  
• Nails larger than 6" are sometimes called spikes.

Styles

• Nail points vary, but the four-sided diamond point is the standard point found on most nails.
  
  
• Nail heads also vary. Smaller heads can be driven in and painted over. Large framing nails have corrugated heads to reduce the danger of a hammer slipping and causing injury or damage.
  
  
• Regular wood nails are often referred to as wire nails.

Material

• Most nails are made from steel or stainless steel.
  
  
• Some nails are galvanized. This means they've been coated with zinc for rust resistance. Galvanized nails are recommended for outdoor applications. Coating can be applied by hot dipping or electroplating. Electroplated nails are shiny, dipped nails have a dull finish.

Coatings and Deformations

• The holding abilities of nails are strengthened by coating or by adding deformations.
  
  
  • An adhesive coating creates a stronger bond. The adhesive heats up as the nail is driven. As it cools, the bond solidifies.
    
    
  • Deformations such as rings, spirals or barbs drive into wood fibers to hold fast.
    
    
  • When using coated or ringed nails, remember that these are more difficult to remove and will damage the wood if they're taken out.
    
    
• Nails with no coating are referred to as bright.
  
  

Nail Type	Description/Use	Click on an image for a larger version.
Box	Fastening when smaller stock is a concern Short, thin shape (smaller than common nails) Has a blunt tip that won't split wood easily
Brad	Attaching molding to walls or furniture Smaller version of the finishing nail. Up to about 1" long
Casing	Attaching case molding or rough trim where strength and concealment are required Similar to finishing nail, but thicker and heavier Has a small head like a finishing nail
Common	Performing construction framing and other rough work Thick, heavy-duty, general-purpose nail Has a large, flat head
Cut Flooring	Nailing flooring through edges without splitting the wood Has a rectangular body Has a blunt tip that won't split wood easily
Drywall	Attaching drywall to wooden studs Has a large head and ringed shank
Duplex	Fastening temporary work — the second head is left exposed for easy removal Double-headed nail Also called Scaffold nail
Finishing	Fastening trim and cabinets when nailheads should not show Small nail with cupped head Can be countersunk with a nailset, then filled over
Gutter Spikes	Securing guttering Long (7-8") galvanized nail
Masonry or Concrete	Securing materials such as wood to brick or concrete Made of thick, hardened steel with grooved or fluted shank Shank can be round, flat or square
Panel	Attaching paneling to walls Has a low profile (similar to finishing nail) Usually has rings Available in colors to match paneling
Roofing	Holding roofing felt, shingles, shakes and metal roofing Family of varied nails for different roofing needs Have large heads and ringed shanks Treated for rust resistance May have metal or plastic washer	Rubber washer, Galvanized roofing nail, square head, plastic cap and metal head (top to bottom)
Sinker	Framing Thick-bodied nail with low-profile head Sometimes called a cooler nail
Spiral	Securing flooring for tight, squeak-free joining Spiral shank nail that somewhat resembles a screw Tends to turn in like a screw as it's driven
Spike	Performing heavy framing work or securing landscape timbers Large nails over 6" long Has either smooth or spiral shank
Tack	Fastening upholstery or carpet or performing other light fastening jobs Very short with relatively large head and very sharp point Made in cut or round form
Upholstery	Attaching upholstery where fasteners will show Short with ornamental or colored heads

For fastening, screws are stronger than nails. They can be removed with less damage to the material (especially wood) than nails. Screws have several features to consider:

Slot Type

• Slotted — the conventional single-groove screwhead, applied with a flathead screwdriver.
  
  
• Phillips — cross-slotted screwheads with U or V-Shaped slots of uniform width. Driven with a Phillips screwdriver, they're used in woodworking and drywall installation.
  
  
• Other head types such as Torx™ or Robertson require special drivers and are commonly used in electronics, metal or automotive applications.

Head Type

• Oval — the lower portion is countersunk and the top is rounded. They're easier to remove and better looking than flathead screws.
  
  
• Round — are used where the fastened piece is too thin to permit countersinking. They are also used on parts that may require a washer.
  
  
• Flat — used in applications where the head needs to be flush with the surface. Slotted and Phillips type are available.

Some Styles

• Self-tapping — cut and form a thread in the material. Self-tapping screws are generally used in fastening to thin sheet metal work. The holding power lessens if the screw is removed and reapplied often.
  
  
• Self-drilling — have points that are designed and shaped like the tips of drill bits. Pre-drilling a plot hole isn't necessary.
  
  
• Fine-thread — work best for hardwoods.
  
  
• Coarse-thread — intended for soft woods.  

Size

• Screws are usually 1/4" to 6" long.
  
  
• Gauge is the diameter of the screw shaft (not including threads), rated by numbers 2-24. A larger gauge number indicates a larger screw.
  
  
• The longer a screw is, the harder it is to turn with a screwdriver. Consider a lag screw when you need something over 4" in length. Lag screws are turned with a wrench.

Material and Finish

• Screws are chrome or brass plated, and can be made from several materials, including brass or stainless steel.
  
  
• Bluing is a finishing (actually black in color) that prevents rust.
  
  
• Some screws are galvanized (plated with zinc for rust-resistance). Galvanized screws are recommended where wood will be attached to metal.
  
  
• Exterior screws such as deck screws can react to certain types of wood. Specially treated screws are available for specific applications such as pine, cedar, birch or oak.
  
  
• Stainless steel can also react to the tannins in certain woods (oak for example). Find an alternate material such as brass or use a treated screw in these cases.

Screw Type	Description/Use
Wood	Securing wood to wood Wood screws are threaded 3/4 of the length of the screw May be made from stainless steel, zinc chrome, or brass Phillips or slotted head Head types can be flat oval or round Work best with a pre-drilled pilot hole
Drywall (or Wallboard)	Attaching drywall to wood or metal studs, performing general construction Long, thin screw with a sharp, self-drilling point. Black in finish Available in fine thread (for metal studs) and coarse (for wood) The threads go all the way to the head	Coarse and fine thread
Deck	Fastening in outdoor applications where strength and resistance to elements is essential Similar is design to drywall screws but larger Galvanized or specially treated for outdoor use
Sheet Metal	Attaching metal components Short, thick screw. Usually zinc-plated, but can be stainless steel or aluminum Heads can be Phillips or regular slotted Head types can be oval, flat, round, or hex Threaded all the way down the shank
Dowel	Fastening end-to-end wood joints Threaded on both ends
Lag	Fastening where maximum holding power is needed Large fastener made to be tightened with a wrench Also called lag bolt
Gutter	Securing guttering Long (7-8") treated screw