Drywall Screw Versus Wood Screw

Drywall screws were originally invented to hang drywall but are now used by many people as an all-purpose fastener. They can sometimes be used in place of wood screws but they do have their limitations. Vice versa for wood screws. Here is how the ubiquitous drywall screw compares to the wood screw.

Drywall Screw

A drywall screw is designed for attaching drywall to wood or metal studs. It is available with either coarse or fine threads. Coarse threaded screws hold better in wood and are often preferred in home construction for wood frame walls. Fine threaded screws are the better choice when using metal studs.

Drywall screws are threaded along their entire length and are self-threading. This allows them to be installed without drilling a pilot hole.  The business end of the screw has a sharp point which makes it easier to stab the screw into the drywall to get it started.

Drywall screws are available in #6 and #8 diameters and in several lengths ranging from just over 1 inch to 4 inches. A common screw length for hanging 1/2 or 5/8 inch drywall is 1 5/8 inch. The screws have a black phosphate coating to help resist corrosion. However, this coating won't prevent the screw from rusting if used in wet environments or for exterior applications. The same applies to standard wood screws.



Wood Screw

A wood screw is used to secure one piece of wood to another. It can also be used to attach hinges, handles, locks, and other hardware to wood. A conventional wood screw has a tapered body and coarse threads with the upper portion of the shank unthreaded. The unthreaded portion improves the ability of the screw to pull mating pieces of wood together. Some newer wood screw designs have a fully threaded shank, allowing them to be installed without a pilot hole if the wood is not too hard.

A pilot hole is often required when installing a wood screw, especially if the wood is very hard or susceptible to splitting. Woods such as oak, cherry, and maple require a pilot hole.

Screw Head Designs

A wood screw with a flat head is countersunk to be flush with or below the wood surface. A raised head screw is countersunk with a slight dome head projecting above the surface. A roundhead wood screw rests on the surface. The head of a wood screw typically accommodates either a slotted or a Phillips bit.

Drywall screws have a flat Philips head or sometimes a recessed square head. Viewed from the side, the head is bugel or cone shaped which allows it to be slightly recessed into the drywall without breaking through the paper layer into the gypsum underneath. To install drywall screws, professionals prefer to use a drywall screw gun which is essentially a power drill with a specialized head that allows screws to be driven into the drywall, just enough to dimple the drywall without puncturing the paper.

Screw Strength

Wood screws have a greater shear strength than drywall screws and will usually bend before breaking. If one were building a bookcase, wood screws would be a better choice than drywall screws for securing the shelves to the case sides.

Drywall screws are harder, more brittle than wood screws and have a greater likelihood of snapping off if subjected to excessive lateral pressure. Although drywall screws can often be used quite successfully for carpentry and furniture construction, this fastener should not be considered as a generic substitute for the wood screw. Drywall screws are best in applications where the material being attached tends to remain relatively stable over time - such as drywall.

Cost

Wood screws are generally more expensive than drywall screws, especially for screws that have corrosion-resistant coatings or custom heads. It's also a matter of supply - millions of drywall screws are used every day for home construction whereas wood screws are used on a much smaller scale for applications such as furniture construction.

See Also

A deck screw is a special type of wood screw that has a corrosion resistant coating and enhanced shear strength - an important attribute because wood will shrink and expand over time due to seasonal variations in relative humidity.