There are several ways to fix composite decking boards. Hidden fastener systems are popular, but many people wonder if you can simply screw the boards down like you would with real wood.
You can screw composite decking, but you must use specific composite decking screws. These are designed to prevent damage to the boards. Pre-drilling is not always entirely necessary, but is advised to prevent damages.
The way that you fix your composite boards is so important, and there are some potential downsides to using screws. This guide will give you all of the information you need so you can make an informed decision about using screws, and ensure that you get it right.
Can You Screw Directly into Composite Decking?
You can screw directly into composite decking if you are using modern composite, and you use the right type of screws. However, some composite manufacturers will void your warranty if you screw directly into the boards because it can cause serious damage if not done correctly, so always check this.
Although they are similar in some ways, composite decking is quite different from wood in the way that it responds to temperature changes. The plastic fibers in composite decking expand and contract a lot more than standard wood. If you screw straight into composite boards with standard screws, you may inhibit that natural movement, which can lead to cracking over time.
Most brands of composite decking are compatible with composite screws, which are designed to be screwed straight in without pre-drilling. These will reduce the chances of cracking and splintering when screwing into composite.
You should always avoid screwing into hollow composite decking as the screw is not secured in the cavity in the middle. Over time, they will come loose and rise to the surface. Many people use clips to secure the deck boards instead of screwing into them to avoid them.
Do you Pre-drill Composite Decking?
Although most modern composite decking can be directly screwed using composite screws, there are some exceptions. If you are using old composite, you need to pre-drill first. You also need to pre-drill around the perimeter of the deck (1 inch from the edge) and on deck stairs.
Bear in mind that pre-drilling your deck boards before you screw them does reduce the chances of cracking, even if you are using composite screws. So, even though it is not completely necessary, you may choose to pre-drill.
When pre-drilling, the most important thing is choosing the right size drill bit. It needs to be wide enough that the screw goes in fairly easily without splitting the wood, but not so wide that the screw comes loose. Pick a drill bit that is as wide as the body of the screw without the thread. If in doubt, go for a slightly smaller size.
What Type of Drill Bit is Used for Composite Decking?
Using the wrong drill bit on composite can cause it to delaminate and split. You need a bit that goes through the composite easily without too much pressure being exerted to avoid this. A solid carbide or diamond grit drill bit are the best choices for this. Although these are more expensive, a cheap drill bit will damage the composite and cause more expensive problems in the future.
What Type of Screws are Used for Composite Decking Installation?
There are specific composite decking screws that are designed for use in composite materials. In most cases, this is what you will use. The threads on these screws are designed to stop problems with splitting, delamination, and mushrooming, which can occur when you use standard wood screws on composite decking. They also come in a range of colors to match the composite decking, and have a UV coating on them so the color doesn’t fade. This allows them to blend seamlessly with your composite deck and give it a flush appearance.
Most brands of decking work best with stainless steel screws, rather than carbon steel, because they’re softer. As composite decking expands and contracts more than normal wood, it’s best to use a slightly softer screw with more movement in it.
What are Some Common Composite Decking Screw Problems?
Although you can use screws for composite decking, there are some common issues you should be aware of.
This is the most common issue you are likely to come across. Screwing into your composite boards always comes with a risk of cracking, even when you are using composite decking screws. The contraction and expansion of the boards is inhibited and, over time, you may notice cracks forming around the screw hole. You can avoid instant splitting by pre-drilling the holes, but eventually, you may have to deal with cracks. You can use fastener clips instead of screws if you are concerned about this.
If cracks do form, you have a few options. Firstly, you can remove the board and flip it upside down, if the underside is not damaged. Alternatively, you can clean the area and use a composite filler to fix the cracks. But bear in mind, these are both short-term fixes and, eventually, the cracks will start to come back.
Before you go ahead with screwing, it’s important that you check your warranty. Some manufacturers specify that you must use fastener clips and your warranty will be voided if you use screws instead. This can cause you big problems if there are other issues with the decking and you can’t get it replaced because you used the wrong fixings.
In some cases, the screws can break inside the boards as the composite expands and contracts. This means that they are no longer fixed securely and if you need to replace the boards for any reason, it’s a lot harder to unscrew them. Usually, this is because the screws are very cheap or you have used screws that are too small for the job. So, invest in good quality screws and go for a slightly large size, especially if you get a lot of drastic temperature changes where you live.
How Do You Cover Screws in Composite Decking?
There are two main methods for covering screws in composite decking. You can cut the composite material into small plugs, and then glue these into the holes over the screws. This is quite a fiddly, time-consuming job, though. Most people opt for an epoxy filler for composite decking. They come in a range of colors so you can find one that matches your deck as closely as possible. You may need to mix it with a bit of thinner and then use a syringe to fill the holes. Once it is dry, sand it down until it is flush with the deck.
Can Drilling into Composite Cause it to Crack?
Drilling into composite shouldn’t cause it to crack as long as you are using the correct drill bit. If you use a standard wood drill bit, however, it could crack. If you are concerned about cracking, you can reduce friction by lubricating the screw with a small amount of paraffin wax.
Can You Nail into Composite Decking?
Yes, you can use nails in composite decking but I wouldn’t recommend it. Firstly, the risk of cracking is higher when you are driving nails into the decking. You should absolutely avoid using a nail gun on composite decking. The other issue is that nails come loose and rise more than screws. Composite moves more than real wood, so nails are far more likely to rise. So, even though nails can be used, screws are a much better option.
There are some benefits to using screws for composite decking. It’s the cheapest and easiest option, and most people know how to use screws. Covering the heads with some epoxy filler is a simple job too. However, it’s crucial that you use good quality composite screws if you want to avoid mushrooming and cracking. Pre-drilling can improve the end result too. That said, many people opt for the hidden fastener systems instead because you get a nice flush finish and you don’t have to worry about any of the common problems associated with screws.
See our related composite decking articles:
- Can You Paint Composite Decking? (All You Need to Know)
- PVC Vs Composite Decking | What’s the Difference?
- How to Finish the Ends of Composite Decking?
- Is Composite Decking Fire Resistant?
- Pros and Cons of Composite Decking
- How Long Does a Composite Deck Last?
- 7 Best Composite Decking Brands
- Can You Pressure Wash Composite Decking?
- How to Keep Composite Decking Cool Enough to Walk On
- 5 Best Sealers for Old Composite Decking
- How Wide Are Composite Deck Boards? (Profile & Size Guide)
Jamie is the founder of The Backyard Pros. When he was 15 years old he started working at a garden centre helping people buy plants, gardening products, and lawn care products. He has real estate experience and he is a home owner. Jamie loves backyard projects, refinishing furniture, and enjoys sharing his knowledge online.