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How Many Screws Per Deck Board?

Screws are an important component in deck construction. They are often used to hold the deck boards in place by fastening them to the joists. However, you may not know how many screws to use per deck board. We have researched this matter extensively for you and here is what we found.

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The typical number of screws per deck board is two for each joist crossing for optimum structural integrity and stability. However, there is no specific rule for the number of screws that should be used on any board. In fact, the more screws you use, the better the strength of the connection, but it also adds to the cost.

Screwing in deck boards is a common practice. But it can be a time-consuming process, especially if you're not using self-tapping screws. Read on as we explain why screws are important and how they are typically spaced out. We'll also give you some tips on how to install deck boards properly.

Carpenter installing a wood floor outdoor terrace in new house construction site - How Many Screws Per Deck Board

How To Screw Deck Boards Properly

terrace deck construction - man installing wpc composite decking boards

For the boards to be properly screwed into the joists, they should be snug but not overly tight. If your boards are too tightly held in place, you run the risk of the wood cracking. The stress of screwing can cause splitting. 

A good way to measure this is to ensure that you can easily slide a screw straight through the wood with minimal torque until it's snug enough.

If you're not sure about how much pressure to use, start by using the least amount and work your way up if necessary.

On the other hand, if you screw them too loosely, the deck boards will shift around during weather changes, causing them to warp. This may not be a problem for the first year or so. But over time, the boards may become loose, resulting in a sagging deck.

To avoid this problem, you may want to use a power drill or drill press to tighten the screws. This way, you'll be able to get the screws all the way into the board and prevent them from backing out.

Additionally, the screws should be long enough to penetrate at least halfway through the joists but short enough to prevent the deck boards from splitting. Generally, a 2.5-inch deck screw is the standard size for most decking projects.

Watch the video below to see how to screw deck boards efficiently:

Should I Pre-Drill Holes for Deck Screws?

It is recommended that you use pilot holes when driving a screw into a piece of wood. This will allow you to easily drive the screw without splitting or cracking the wood.

However, it is important to note that drilling pilot holes for each screw can also be very time-consuming. This is where self-tapping screws come in handy. Self-tapping screws can cut your screw installation time in half. 

There are a couple of reasons why a self-tapping screw may be preferred over a standard screw. First, they are a bit easier to use, since they don't require you to pre-drill holes. You simply drive the screw into the material, and it taps its own hole!

Second, they tend to have better holding power. The threads inside of a self-tapping screw are very sharp, so they can hold the screw in place better than a regular screw.

The amount of force needed for a self-tapping screw is relative to the hardness of the material you want to penetrate.

Check out this self-tapping screw on Amazon

How Deep Should a Pilot Hole Be for a Wood Screw?

When installing a screw into wood, a pilot hole is first drilled into the wood. This hole acts as a starting point for the screw to enter the wood. Generally, you should make sure that your pilot holes are large enough to accommodate the screw's minor diameter. 

Importance of Spacing Screws And Deck Boards

Spacing is important, as this allows for more space between the deck boards for moisture to escape. It also allows leeway for the wood to expand and contract caused by temperature changes.

Since wood expands and contracts and the thickness of deck boards vary, the best way to ensure stability and a professional look is to use consistent screw spacing.

If you're unsure of how far apart to space the screws, don't worry. Screws are placed at certain intervals at your discretion to ensure proper support of the wood. In other words, spacing screws on your deck boards is a personal judgment call that is dependent on your circumstances.

Needless to say, the lack of proper spacing can also increase the possibility of rot by allowing excess water to be trapped in the joists. This happens during wet and cold seasons when the temperature is not high enough to evaporate the water, and there is no proper ventilation at the bottom of the deck.

This causes the wood to naturally expand and contract, which can result in cupping.

Remodeling a deck in a suburban backyard. The contractor is laying down composite wood , has once PVC railing in place, and there is a giant saw. The tool is sitting in the demolished deck.

What is Cupping?

Cupping is caused by moisture building up on the underside of your deck boards. Moisture causes the wood to swell. As this progresses, the deck boards can begin to expand beyond their original size and eventually deform into a cup-like appearance, thus the monicker.

In the lumber industry, the cause of cupping usually has something to do with poor construction or incorrect drying methods. Poorly dried lumber will shrink when exposed to humidity and heat and will cup over time.

Wood that has been allowed to get moist and dry slowly without proper ventilation will experience similar issues. It is important to keep in mind that this process only happens over time.

How Do I Prevent Cupping?

Cupping is an inevitable part of the aging process for most hardwood species, but you can delay its progress. The best way to do this is by installing proper ventilation and spacing between screws and deck boards.

Ventilation allows for the wood to dry out, breathe, and prevent expansion. On the other hand, proper spacing prevents the deck boards from being forced out of shape.

Should Deck Boards Be Butted Together?

Yes, we recommend that you use butted boards to reduce any issues associated with gaps and to maximize water egress. If you're installing your own deck, you can cut the deck boards to length, but it's important to note that you should always plan ahead for trimming the boards to size as they will inevitably shrink when drying out.

Old silvered and weathered wooden decking

Recommended Gap for Deck Board Spacing

As far as gaps go, a 0.125-inch gap is considered adequate. This is what will usually be left between the boards after the wood has completely dried.

You want to make sure the gap between your deck boards is wide enough to allow moisture to exit, but not wide enough to compromise stability.

Which Way Should Boards Run on A Deck?

wpc terrace construction - worker installing wood plastic composite decking boards

Most types of decking boards can be laid with either the ridge or the smooth side facing up. There are a couple of reasons why you might choose to have one side of the decking board face up rather than down.

First, having the rough side up allows water to run off more easily and also allows rain or snow to fall off the board.

Second, when you lay your decking boards, you want them to be evenly spaced and even across the entire length of the deck. When the rough side faces up, the ridges on the board give you a better chance of ensuring that every board will be laid evenly.

However, the ridges are originally designed to maximize airflow underneath the decking structure. If you do not have enough airflow under the decking boards, then this will slow down the evaporation of moisture, and we already know how this can lead to decay over time.

Is It Better to Seal or Paint a Deck?

Paint is used to coat objects such as wood, concrete, vinyl, etc., for the purpose of providing protection, altering appearance, or changing surface characteristics. While there is no definitive answer to the question, we've seen plenty of homes that have had a significant amount of success with painting.

This is because painting can provide better UV protection from sunlight and mold infestation.

Check out this Kilz deck paint and wood resurfacer on Amazon

In Closing

As long as there are adequate screws to hold the boards together, you don't need to have the same number of screws on each side of a board. The only reason we can see for not having more than two screws is to provide enough leeway between the screws. You may choose a deck screw with a bigger thread diameter than usual, so spacing is crucial to avoid splitting your board.

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