Screws are one of the most useful fasteners because their threads pull one piece of material into the other. As you read directions for screwing things, you might notice that some call for drilling a pilot hole while others do not. You are wonder if you should drill a pilot hole for wood screws. In this post, we incorporate carpenter experience and research to answer your question thoroughly.
Whether or not to drill a pilot hole (or pre-drilling) is a decision most contractors make every time they start a new screw-related project. Factors to consider when deciding to drill a pilot hole include the following:
- Advantages of predrilling
- Disadvantages of predrilling
- Project size
- Desired finish quality
- Experience of carpenter
- The durability of the wood
- Type of wood screw
Keep reading the rest of this post for a rundown on the necessary information to make a wise decision about when to drill pilot holes for wood screws. We include directions on how to drill pilot holes, how wide pilot holes should be, and a review on how to choose your wood screws.
Why should you drill a pilot hole (Pilot Hole Advantages)?
When deciding whether to drill a pilot hole or not, it is beneficial to understand the advantages of predrilled screw holes. Predrilling screw holes allow for a more exact screw location, avoids potentially splitting the wood, produces a more solid connection, and makes driving the screw easier.
Predrilling allows for more precision because drill bits travel through wood much easier than screws. So, where a screw will jump and turn on grain and imperfections in the wood, the drillbit will travel much straighter.
Avoids Splitting the Wood
As a screw enters the wood, the force of the drill or screwdriver combines with the tilt of the threads to carry the shaft through the wood. As this happens, the wood is being split apart. This can visibly separate the wood. Predrilling holes, on the other hand, removes some wood which means the screw exerts less sideways pressure.
Produces a More Solid Connection
In the same way that predrilling holes help avoid splitting the wood, it also improves screw holding strength. Since the wood is not being pushed apart by the screw, the screw threads can grip and hold the two pieces of wood together more firmly. That is to say, the pressure on the screw is all in the correct direction.
Ease of Drilling
The ease of drilling a predrilled screw is the most obvious of the predrilling advantages. Put, by removing some of the wood, the screw will sink fully with far less force required. This also helps to foster a solid connection and a completely sunk screw.
Disadvantages of Predrilling Screw Holes
The main disadvantage of predrilling screw holes is that it requires additional time and effort. Rather than just a single driver bit and drill, you need at least a second bit to make the hole. Many prefer predrilling for larger projects with two drills, one for the driver and one for the auger bit. Even in this circumstance, switching between tools and tasks will add time and effort to any projects that use predrilling.
Further, and as described above, predrilling requires the additional tool of the wood auger bit and sometimes a second drill. These are not extremely expensive or hard to find but are essential to the predrilling process.
Deciding When to Predrill Screw Holes
Deciding when to predrill screw holes is a matter of weighing the advantages and disadvantages of the technique. While the previous sections introduce this decision matrix, the following subsections add additional information to help you decide if you will predrill your screw holes.
Generally speaking, the larger the project, the less likely a contractor will predrill holes. For instance, a large deck fastened together with screws would take a very long time to build if you needed to predrill every hole. So, for time’s sake, it is often not worth predrilling screw holes for larger projects.
Desired Project Quality
Predrilling screw holes improve overall project quality. This means that if your goal is high-end, the more durable finished product, predrilling, is likely the move for you. In the same sense, the increased quality is usually worth the small added extra time for small projects.
Even for some small projects, a practiced handyman can confidently sink a screw to join two pieces of wood precisely. For projects that do not require a high degree of finish, skipping the predrilling step is likely a fair call.
For many situations, individuals experienced using a drill to screw into wood gain the technique and know-how to drill well without a pilot hole. But remember, no one is an expert on their first try. If you are inexperienced using drills and screws, predrilling pilot holes is a wise choice.
Durability of Material
This factor regards how likely the wood is to split. Some wood is just more fragile than others. Say, for instance, that you are building a 1,000-square-foot deck using screws, and you find that boards are starting to split. No matter your experience, it is worth the extra time to predrill your holes to avoid this costly and unsightly issue.
Type of Wood Screw
There are many types of wood screws, but this post will consider self-tapping, non-self-tapping, and very large wood screws. Self-tapping screws are tipped by what appears to be a small auger bit. Non-self-tapping screws have a thread all the way to their tips.
The auger bit of a self-tapping screw helps push the wood out of the way as the screw is sunk. These screws are much easier to drill in without a predrilled hole. Non-self-tapping screws can be very difficult to fully drill without a pre-drilled hole. This means that if you have a lot of screwing off to do, opt for the sometimes pricier self-tapping screws.
The final screw-type considered here are very large screws. Screws that are very wide or very long often require more torque to fully sink than an average person or battery drill can provide. To assist the process, predrilling the whole is an excellent option.
How to Drill a Pilot Hole
Drilling a pilot hole is a relatively simple process. First, place the two pieces of wood in their desired position. Sometimes, this might require a helping hand or clamps. It is essential to place the pieces in their final position because once the pilot hole is drilled, it is difficult to move.
Using a power drill, drill an appropriately sized pilot hole as deep as the screw is long. If you are worried about drilling too deep, you can premeasure the drill bit and mark it with masking tape or a sharpie.
For a more visual introduction on how to drill pilot holes, watch this YouTube video.
How much smaller should a pilot hole be than the screw?
A pilot hole should match the size of the screw shaft. That is to say; the auger drill bit should be the same size as the screw if the screw had no threading. The logic of this is only the threads are holding the joint together.
This means that a hole the size of the screw shaft removes all the unnecessary wood but leaves the wood required for the threads of the screw to bite. Drilling a pilot hole smaller than this will make the screwing job more difficult. While drilling a pilot hole bigger than the screw shaft will reduce the screw’s holding strength.
Can you make a pilot hole without a drill?
It is possible to make a pilot hole without a drill. However, it is more work and not as effective. The most common drill-free technique is to use a nail and hammer to make the pilot hole. Take a nail the size of the screw shaft and drive it into the depth of the screw. Make sure to leave the head of the nail showing to facilitate the nail’s removal.
Be careful; the nail technique runs the risk of splitting the wood. Further, when pulling the nail, it is easy to mark or mar the face of the wood. This can be a problem for highly visible areas in and around the home.
What are the best screws for wood?
There is no single best screw for wood. There are, however, usually great choices for the job at hand. Issues to consider are screw strength, screw length, head appearance, price, availability, and self-tapping capabilities.
For most projects, self-tapping screws are advisable even if you plan to pre-drill because of their ease of use. Further, if you are concerned about screw strength and durability, opt for the more expensive screws – you will usually get what you pay for. If you are still unsure of what screws to buy, head to your local home improvement or hardware store and ask the help of a professional.
For more help from home Decor Bliss on choosing the right screw for your job, read this great article: What Screws And Nails To Use For Wood Framing?
In this post, we have answered the question of whether to pre-drill screw holes. We cover the advantages and disadvantages of pre-drilling holes as well as several other decision-making factors. To conclude, we provide directions on how to pre-drill screw holes and advice on which screws to choose. Good luck!
For more reading, check out this great article about drilling through porcelain tile: How To Drill Through A Porcelain Tile In 5 Easy Steps.