Screws and nails are commonly used fasteners for all home woodworking projects. They both work great and make a strong and secure connection.
But is one better than the other when it comes to framing?
Framing is connecting two different building materials to create a finished structure. This can be anything from flooring, joists, studs, rafters – you name it!
These structures need to be secure as they create the foundation of your structure. So picking the right fastener here is vital!
The main difference between screws and nails is that, in general, screws have better holding power thanks to their shape and design. Their tensile strength (the ability to withstand pressure pulling two pieces of wood apart) is fantastic.
But, they are a more expensive option and can be susceptible to shearing.
Nails, on the other hand, are essentially the opposite because they are better at bending and won’t just shear off, meaning they are far better at withstanding side-to-side or lateral pressures.
That said, because there are no threads on a nail and it just has a smooth surface, it has a far lower tensile strength than screws and, when subjected to pulling pressures, may even work themselves loose over time.
But they are a far cheaper option and have the added benefit of being more ‘hidden’ when driven into wood.
However, this is speaking for general wood screws and nails – in recent years, we have seen specialty screws specifically designed for construction become more popular, which complicated the topic somewhat.
So let’s dig into their differences a bit deeper so you can better understand these two fastener types and their relative strengths and weaknesses.
What is a screw?
If you’re unfamiliar with a screw, it consists of a screw head with a cross-shaped groove cut out of it, which you can fit the end of a screwdriver into.
From that screw head is a long shaft wrapped in a metal threading that extends the length of the screw. This shaft is then screwed clockwise into the wood, and this threading naturally helps to draw the screw into the wood and creates a solid binding connection.
Screws have incredible grip strength thanks to this threading and are used throughout the woodworking and construction fields. But they have a reasonably low shear strength and aren’t designed to handle lateral movement well.
There are many types of screws available, including machine screws, lag screws, and metal screws – but the most common type, and the one we are referring to under the topic of framing, is the typical wood screw.
What is a nail?
By comparison, nails are a much simpler object. While serving the same fundamental purpose as screws, their qualities and intended application are slightly different.
A nail consists of a flat head with no groove cut out, as it’s not intended to be used with a screwdriver. Instead, it’s driven into the wood using a hammer.
From this head extends a long shank that ends in a point.
Because the surface of a screw is smooth and it doesn’t have any threads along the shank/shaft, it has a far lower gripping power than screws. But don’t mistake the lack of threads, as nails are useless. On the contrary, they are commonly used over screws in certain wood framing scenarios.
This is primarily thanks to their high resistance to lateral movement (which we also refer to as shear resistance). They are more likely to bend a little rather than shear off.
And while sometimes screws are preferred even in a scenario where a nail might have sufficed thanks to how reversible it is, you may also find the opposite happen where nails are used simply because they leave a small imprint on the wood thanks to their smaller heads.
What are the differences between screws and nails for framing?
So while at first glance these two fasteners might be used for essentially the same thing, when you take a closer look at their individual qualities, it becomes very apparent that they are better suited towards different things.
Depending on the kind of join you are making, the forces that will be exerted onto it will make one or the other significantly more efficient in that given scenario.
Let’s take a closer look at these different qualities so you can better decide which one is right for you.
1. Sheer resistance
When a fastener, whether nail or screw, is installed in between two pieces of wood, two kinds of forces will be exerted upon it.
You have a vertical force, which is essentially pulling in the direction along the length of the nail/screw. Then you have a horizontal force, the lateral movement that exerts pressure onto the sides of the fastener.
When the lateral forces are more significant than the strength of the fastener, there is the risk of a more brittle material snapping or ‘sheering.’
The available wood screws that you’d use for most construction have a weak sheer resistance. So if you were to use them to fasten something like a joist to a deck, the left and right forces exerted on the screw give it a high likelihood of sheering off.
This is both dangerous to the structure and troublesome to deal with, as when you want to remove the screw, you need to dig out the second half of the screw that’s still left in the wood.
So when it comes to sheer strength, finishing nails are generally considered the better option as they have a little give and are slightly bendable. They will very rarely snap. And because in a vertical force exertion scenario, their grip strength is less of a factor as gravity is working in your favor – nails at the best choice.
2. Tensile resistance/grip strength
Unlike sheer strength, where we look at lateral forces exerted on the fastener, grip or tensile strength refers to the fastener’s ability to hold the two pieces together.
As the main shaft of a framing nail is smooth, it doesn’t do quite as well at gripping and holding two pieces of wood together.
Because screws have a thread that bites and grips into the wood as it’s screwed in, it creates considerable resistance against pulling forces. So any situation where tensile strength is a priority – screws are your best choice!
Many different types of finishing nails and screws are designed to serve other purposes and come in at different prices.
In general, wood screws are a more expensive option than nails. So in a scenario where you need a lot of fasteners, nails might be a better option. However, there are also situations in which nails will not have enough grip strength to do the job, in which case you will have to opt for wood screws.
4. Ease and speed of use
Nails are considerably easier and faster to use than screws. You need to line them up and strike the head of the framing nail with a hammer to drive it into the wood. You can also purchase nail guns which will automatically drive the common nail into the wood with essentially zero effort required by the user.
Screws, on the other hand, require the screwdriver to be inserted into the recess on the head, then it requires turning manually to drive it into the wood. While it’s also possible to use a drill to speed things up, it still needs far more care and effort when compared to a common nail.
5. ‘Footprint’ left on the wood
When screws are used, even when you recess them, the entire head of the deck screw is still visible. At the same time, nails have a much smaller authority and are far less visible once hammered into the wood.
As wood screws are so rigid, providing you line them up correctly, they will screw in a straight line and never ‘drift’ midway through.
Nails, however, are pretty easy to bend, so even when lined up, they might bend midway through and drift away from the intended path. They might also snake and create an S shape if driven in with too much force.
7. Wood splitting potential
Because nails are thinner and more malleable, they will rarely ever cause wood to break and splinter.
Wood screws, on the other hand, are much thicker and more rigid, meaning that they have the potential to split thinner pieces of wood apart due to the forces they exert on the wood fibers.
Screws vs Nails for Framing: Are they the same?
So as you can see, although there is a certain degree of crossover between these two fasteners, they have unique qualities that make them better for particular scenarios.
- Nails have a higher sheer resistance due to their ability to bend.
- Deck Screws have a much higher grip strength thanks to the threads that run the length of the shaft.
- Nails are generally cheaper than a deck or floor joist screws.
- Screws are a bit slower to install and require more labor than nails.
- Nails leave a smaller imprint on the wood as the head of the nail is smaller than that of a screw.
- Screws are rigid and, therefore, accurate when installed into the wood. At the same time, nails can be drifting or snaking as they are driven in.
- Because screws are thicker and more rigid, they are much more likely to split wood than nails.