Choosing the right screw for different applications

There are several types of screws out there depending on the material you are working with and the application. Here's an overview including some suggestions for screws for common applications.

The two basic types of screws are machine screws and wood screws.  Machine screws are made to thread into a threaded hole or a threaded nut. They are not pointy at the end.  Wood screws are made to dig into wood using the threads to cut into the wood as it drives in. The end is sharp and the threads are typically farther apart and sharper than a machine screw. This article focuses on wood screws.

Screws can be made of:

• Steel--Most screws are steel and typically are zinc plated for rust protection. These are good for most applications.
• Brass--Is mainly for decorative screws. It does not rust but is soft and easy to damage with a power driver.
• Stainless steel--comes in various grades but they are the best screw for exterior applications as they will not rust. They are more resistant to breakage than brass but they are still softer than steel. They are quite expensive compared to steel screws.

Screws also have several types of head shapes (i.e. pan head, flat head etc)

• Round head--have a semi circular dome on top and are flat on the bottom. They are made to sit on the surface of a project.
• Pan head--like round head but with a more flattened dome
• Flat head--sit in a recess called a counter sink so the top of the screw is flush with the surface it's installed in
• Oval head--a cross between a flat head and a pan head

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Different screws have different recesses (they take different driver types, slotted, phillips etc)
Slotted and phillips are the most well know but square drive is becoming increasingly popular.

• It's easy to strip the head on slotted screws so it's important to use the right size screwdriver and it's nearly impossible to use a power driver. 
• Phillips head screws are the most common and if you use the right size bit (#2 being the most common) you can drive them with a power screw driver quite successfully.
• Square head are designed for use with power drivers and are far more resistant to stripping the head than the other two.

Here are several common applications for screws and the most appropriate screw for each.

• Outdoor decking: Stainless steel, flat head, square drive You want the screw to go into the joist at least as far as the decking is thick. So a 3 inch screw is best used with standard decking (that is approx. 1.5 inches thick). Because stainless is soft; it helps tp pre-drill holes.
• Hanging drywall: Steel, bugle head (similar to flat head), phillips. For this application, there are screws labeled as "drywall screws" that work great. For 1/2 inch drywall use 1 1/4 or 1 5/8 inch long screws. 
• Hanging cabinets: Steel, pan head, square drive screw. Be sure to drill a pilot hole through your cabinet and use a 3 " screw.
• Door hinges:Brass (usually, depending on your hinge)  #9 flathead, phillips in inch long or even 2 1/2 inches long for security on entry doors.
• Attaching something to drywall: If you are hitting a stud, be sure to account for the thickness of the drywall and still penetrate the stud at least one inch. If you don't hit a stud, check out the other Refurber article linked to this one.

If you need a lot of screws, they can be ordered online for a good price from McFeely's Square Drive Screws: www.mcfeelys.com (that's the vendor we use at our house.