Home Tips & Advice

Selecting and Using Screws and Nails

Here are tips and suggestions to help you do a better job when using common fasteners like screws and nails. Although there is nothing complex about a nail or a screw, many are misused.

  • Selecting the Proper Nail and Using it Correctly
  • Selecting the Correct Screw and Using it Properly

SELECTING THE PROPER NAIL AND USING IT CORRECTLY

  • Although there are many different types of nails and brads, four types will handle most fastening jobs.
  • The common nail is most widely used (see image). It has a flat head and is used where the appearance of the nail head is not objectionable.
  • The length of a nail is identified by its "penny" size. In the early days of nail manufacturing, this term designated the weight of nails per hundred. Today it designates only the length and size of the nail.
  • The designation 2d, 3d, 4d, etc., identifies a 2-penny, 3-penny, 4-penny nail, etc.
  • The casing nail is used primarily on cabinet work or interior trim (see image). Casing nails are slightly heavier than finish nails.
  
  • The heads of casing nails are normally countersunk and covered with putty or wood filler.
  • Finishing nails have rounded heads that can be driven flush with the surface of the wood (see image). Although they are often countersunk like casing nails, they can be used without countersinking.
  
  • Common brads are designated by length only (see image).
  • Brads are recommended for light assembly work where the head should be concealed. They are thinner, shorter, and smaller than finish nails.
  • Use the nail selection chart for selecting the proper nail or brad for various thicknesses of wood (see chart). The chart shows the recommended type and size of nail or brad for woods of various thicknesses.
  
  
Nail Selection Chart
Plywood ThicknessType of NailSize
3/4"casing6d
finishing6d
5/8"finishing6d - 8d
1/2"finishing6d - 8d
3/8"finishing4d - 6d
1/4"brads3/4" - 1"
finishing3d
lath1"
  • You may want to make some variations from the chart, but it can be a practical guide in nail selection.
  • Here is a rule of thumb to remember: The nail should always be about three times as long as the thickness of the wood through which it is driven (see image). Nails are normally driven through a thinner piece of wood and into a thicker one. This allows 2/3 of the nail to provide holding power in the thick piece of wood.
  • To help you pick the right length of nail, hold the nail up against the thin piece through which it is to be driven. Then select a nail approximately three times this thickness (see image).
  • This image illustrates how to countersink a nail. First, select either a casing or finish nail and drive it into the wood, leaving the nail head slightly above the surface.
  • Select a nail set with a head the same size as the head of the nail and drive the head of the nail slightly below the surface with the nail set.
  • Remove the nail set and fill the recessed area with wood putty or wood filler.
  • Let the putty dry, then sand it flush with the surface of the wood.
  • You can conceal nails in a piece of wood by taking a wood chisel and digging a slight hole into the wood in the direction of the grain (see image, part A).
  • Drive a finish or casing nail into the hole and replace the chipped-out wood with wood cement. If done properly, this will provide a strong holding power and the nail will be completely hidden (see image).
  • Bend nails over at the end when attaching two pieces of wood where appearance is not important. Bending the nail over increases the strength of the joint (see image, part B).
  • Use care when driving nails near the end of a plank. Never drive two nails in the same grain of the wood near the end. Always move over to another grain of wood for inserting the second nail (see image, part C).
  • When you must nail an upright piece of wood to a flat surface, toe-nailing with casing or finish nails will do the job. Drive the nails completely in to provide a strong holding power with a neat appearance (see image, part D).
  • A special type of nail is available for wallboard (see image). This type of nail practically eliminates the popping problem.
  • The rings around the body of the nail give it an extra-strong holding power. The dish-shaped head can be driven flush with the surface of the wallboard to provide a neat appearance.
  • The image below illustrates various types of fasteners that are helpful for specific fastening jobs.
  
  • A special nail is available for holding wood to concrete (part A). With a little patience and practice, the concrete nail can be driven into concrete or masonry.
  • A ring nail provides a strong holding power for special nailing jobs (part B). The annular rings around the nail have sharp ridges that lock into the wood, making it practically impossible for the nail to slip.
  • Ordinary corrugated fasteners are used for fastening corners or where one piece of wood butts against another (part C).
  • Upholstery nails are designed for fastening materials to wood on both flat and curved surfaces (part D). They can be used to cover unsightly tacks.
  

SELECTING THE CORRECT SCREW AND USING IT PROPERLY

  • This image illustrates the six types of common screws. These screws can be divided into two basic types: slot-head screws and Phillips-head screws.
  • Both types of screws are available with flat, round and oval heads.
  
  • This image illustrates how these three different types of common heads look when driven into the wood.
  • The oval-head screw extends above the surface in a slight oval. The round-head screw protrudes above the surface in a half-circle. The flat-head screw is flush with the surface.
  • Two basic types of screwdrivers are needed for driving the different types of screws (see image below).
  • The regular slotted screw has a slot in the head, while the Phillips-head screw has a cross slot.
  • Always use the proper screwdriver for the screw you are using.
  • Use the screw selection chart for selecting the correct size and length of screw for any job (see chart). This chart is designed for flat-head screws but can be used for any type.
  
  
Screw Selection Chart
Plywood ThicknessFlat-Head Screws
ScrewLengthPilot Hole
3/4"#81-1/2"5/32"
5/8"#81-1/4"5/32"
1/2"#61-1/4"1/8"
3/8"#61"1/8"
1/4"#43/4"7/64"
  • The column on the right shows the size of the pilot hole to be drilled for starting the screw.
  • The chart below gives the relative size of the head and shank of screw sizes ranging from #2 to #16. This will help you select the proper size screw quickly and easily.
  
  • This image shows how to join two pieces of wood with screws. Of course, some of these steps are not always necessary, but under normal conditions you'll get a neat bond with excellent holding power.
  • First, make a mark where you plan to insert the screws. Carefully position the two pieces that are to be attached. Securely hold the two pieces together and drill a pilot hole through the top piece into the second piece (see image, part A). The pilot hole should be slightly smaller in diameter and as long as the screw. A piece of tape on the bit will help judge the depth of the hole.
  • Using the pilot hole as a guide, drill a hole slightly larger than the screw shank through the top piece (see image, part B).
  • Use a countersink to drill for countersinking oval or flathead screws (see image, part C).
  • Insert the proper screw. Tighten the screw for a neat and strong bond of the wood.
  • You can make this job easier and the results better if you clamp the two pieces of wood together while you work. If you do not have clamps, drill, countersink and tighten one screw first. This will act as a clamp. Then do the remaining screws.
  • Use a dowel plug if you want to completely conceal the head of the screw (see image).
  
  • Cut the holes for the dowel plugs with an ordinary countersink. Simply drill a bit deeper with the countersink than you would for a regular countersunk screw.
  • After drilling the hole for the plug, cut a piece of dowel of the proper size to make the plug.
  • When the plug is inserted and glued into place, it can be sanded flush with the wood or rounded off.
  • Screw washers are available for flat-head, round-head or oval-head screws (see image).
  • Use ratchet or offset screwdrivers to insert screws in inaccessible areas. These screwdrivers make it easier to reach such areas (see image).
  • Drill a hole and insert a dowel to keep the end of a piece of wood from splitting when screws are inserted. This provides a different run of the grain in the wood and makes splitting unlikely.
  • Sometimes it is necessary to counterbore a thick piece of wood when it is to be attached to another thick piece of wood.
  
  
  
  
  
  
  
  
  
TOOL AND MATERIAL CHECKLIST
ScrewsSlotted Screwdriver
Hand DrillWood Chisel
Ratchet ScrewdriverDowel Plugs
Folding RuleNails
HammerCountersink
Brad PuncherNail Set
AwlOffset Screwdriver
Screw WashersQuality Wood Glue

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Check your state and local codes before starting any project. Follow all safety precautions. Information in this document has been furnished by the North American Retail Hardware Association (NRHA) and associated contributors. Every effort has been made to ensure accuracy and safety. Neither NRHA, any contributor nor the retailer can be held responsible for damages or injuries resulting from the use of the information in this document.

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