A Complete Guide to Wood Screws

Wood screws are mainly used for secure connection of wooden materials. They work with chipboard, MDF, softwood and hardwood. There are many types of wood screws available, complete with features such as shanks to avoid wood splint, twin threads for effective drive, and tips meaning holes don’t have to be pre-drilled. You can buy wood screws complete with various drive types and head shapes. However, the Pozidriv and countersunk head varieties are the most popular.

Originally, wood screws were made of brass or steel and featured a shaft with increasing thickness in proximity with the head. It was necessary to drill a pilot hole for the secure fitting of this screw type. However, the modern wood screw has a shank of uniform size in relation to the head. This means that drilling a pilot hole isn’t always necessary.

It is highly important to select suitably sized screws. The thickness of your chosen screw should correspond to the width of the wooden material. You should also ensure that the screw is capable of supporting the weight of the load to be applied.

The diameter or gauge of the screw will be indicated by a number, with the most common wood screws being the #6, #8, and #10. The increasing numbers relate directly to the thickness of the screw. As a rough guide, the #8 screw is recommended for general purposes whereas a #6 screw would be better suited to fine woodworking.

We stock a range of different sized wood screws, as highlighted in this chart:

Wood screws come in either partially or fully threaded varieties. Steel screws are considered to be the best for woodworking and interior DIY due to their strength and versatility. It has become common to use ‘production screws’ for such purposes. They feature defined points and threads with sufficient strength and sharpness to penetrate the hardest types of wood. These screws also have the durability required to withstand high power driving and drilling.

Wood screws have a pointed tip, so can be guided into the wood with precision. The threads of the screw wrap around the shank, enabling the screw to be securely driven in. It is advisable to use fine threads for hardwoods and coarse threads for softwoods and plywood.

The two most important characteristics of screw heads are the shape and drive type. There are a wide variety of drives, but the main ones are as follows.

Slothead screws are the most common variety used for driving the screw. They feature a simple slot that can be turned with a flathead screwdriver for penetration of the material.

Phillips head screws have much greater functionality than the slothead variety. They can be securely inserted into a range of wooden materials. However, there may be some slipping when driving the final section of the screw into the wood. This often results in damage to the screw and driver.

Square drive or Robertson screws have a number of advantages over the Phillips head variety. These screws feature a square head, greatly reducing the risk of slippage. They are commonly found in pocket screws.

Starhead screws have also become increasingly popular for woodworking applications. They can be fitted with the assurance of reliability and can also accommodate large amounts of torque.

Take a look at the wood screw head type varieties below:

As previously mentioned, wood screws are available in a range of materials. You can buy brass, bronze, and aluminium screws for different applications. However, steel screws are the most popular and the most commonly used variety.

There were issues associated with the use of traditional tapered steel wood screws that made many people choose affordable screws for plasterboard. These screws could be easily driven into wallboard and studs without the need for pre-drilled pilot holes. Unfortunately, they were quite brittle and known to snap under high pressure.

Problems associated with the use of plasterboard screws prompted many people to opt for modern production screws. These strong and reliable screws can penetrate various types of hardwood and some metals. They can also withstand high-intensity driving.

Steel deck screws are commonly used for outdoor applications due to their high levels of corrosion resistance. Silicon bronze and stainless steel screws can also be used where corrosion is a particular concern.

It is essential that you select a wood screw of the appropriate length and strength. Heavier screws should be used wherever there is a need for high-level holding power. It will also be necessary to choose a screwdriver with a suitably sized tip (it should fill the recess). As previously mentioned, it won’t always be necessary to drill a pilot hole before penetration with the screw. However, we will outline the complete process here:

Step One: Mark the Spot

Mark a cross in the exact spot where the pilot hole is to be set.

Step Two: Drill Down

Drill directly into the area indicated by the cross.

Step Three: Create a Hole

Make a large and shallow hole where countersinking is required.

Step Four: Drill the Screw

Begin the drilling process with a hand driver and finish with a power driver (set at a reasonable speed to prevent screw hole stripping).

The appropriate choice of the wood screw will largely depend on the type of wood. You will see the size of the screw clearly marked on the box. As an example, the size indication may be 5.00 x 75. Each of these figures equates to millimetres, with the 5.00 referring to the gauge of the screw and the 75 referring to the length.

Raised head and round head screws can be used whenever a decorative finish is required. They are particularly well suited to the fitting of household furniture. There is also the option of buying counterhead screws, featuring a head which will be positioned flush with the surface of the wood. The standard woodscrew is a good example, suitable for the majority of home fittings. Brass wood screws are resistant to rust and corrosion of oak timber. Stainless steel screws may also be used for such reasons.

Can Wood Screws Be Used in Plasterboard?

Purpose-made screws have traditionally been used to hang plasterboard. However, they do have some limitations when compared with wood screws. They will rust if fitted in environments exposed to continuous moisture. The alternative is to fit flat countersunk deck screws in order to minimise the risks of splitting, cracking, and weakening. Such screws also feature a shank designed for continued durability and secure fitting.

How Long Should a Wood Screw Be?

Factors such as the type of wood, screw material, and lateral vs sheer forces will have a bearing on the appropriate length of the screw. However, there are some general guidelines that should be applied in the selection process.

You should ensure that the screw can penetrate a minimum of half the thickness of the bottom material. The screw should also be suitable for the secure fastening of two boards as required. There shouldn’t be any protrusion.

How Much Weight Can A Wood Screw Hold?

There are various coarse-threaded wood screws that can hold weights in excess of 100 pounds when attached to purpose-made wood studs.

Do You Need to Use Pilot Holes for Wood Screws?

It is recommended that you drive in appropriately sized pilot holes before fitting screws. These holes should be inserted to stop the wood from splitting or cracking when fitting the screws. This will be particularly important when inserting screws into woods with complex structures, such as oak.

The insertion of a pilot hole will enable the screw to be easily guided into position. It should also be relatively easy to screw with a power drill or screwdriver. Without the pilot hole, there will be a significant risk of breaking the screw when a high level of pressure is applied.

Can You Use Wood Screws for Brick?

You should use masonry screws rather than wood screws for brick applications. The masonry screws are specially designed for use without a lag shield, plug, or alternative anchor system. They have longer threading (may be two inches or more) and different patterning to the wood variety. Masonry screws are also commonly used for metalworking purposes.

How Far Should Screws Go into Wood?

The thickness of materials being joined and the orientation of the parts of the joint will have a direct bearing on the appropriate screw length. You are advised to use a screw of at least 2 to 3 times the thickness of the material being added. It might be necessary to try screws of various lengths before identifying those best suited to your purposes. If the screw doesn’t fully penetrate the material allowing for tightening, then you should cut off the end. It will be necessary to apply a screw of a shorter length.