Do You Leave Gaps Between Composite Decking Boards?

Henry A
Installation
gaps between decking

Installing Ultradecking is possible without any professional help, especially if you have prior experience and knowledge in building. However, in the construction process, there are many small yet crucial details that you have to observe and follow. These aspects will affect your decking, especially its longevity and durability. One of the most important things that many forget or don’t realise is to leave gaps between composite decking boards. But the question is, do you need to do it? Why is it so important?

Decking Spacing and Why it’s Important

When you install composite decking, especially if you go down the DIY route, you have to remember to leave a gap between composite decking boards. Many people who try to build decking for the first time often forget about this crucial detail. Why is it critical?

One of the main problems with decking is the expansion and shrinking of the decking boards. Composite expands in the heat and contracts in the cold, therefore, when installing, close attention must be paid to the weather conditions during the installation. All boards will expand when exposed to high temperatures, while others are prone to moisture. However, the former is more common for composite decking boards.

When your decking shrinks, it can cause some accidents in your home. The gaps may become too big that some people may trip when walking on the decking. With too much air, it can also decrease your decking’s resistance to fire.

On the other hand, if there’s not much room for decking boards to expand, which they will eventually do, they can create friction and damage each other. Worst case scenario, due to the pressure from the expansion, the decking boards can warp, twist or even rise away from the substructure with splits and cracks appearing.

Water Drainage

Aside from that, decking boards that are too close to each other don’t drain water as fast as boards that have sufficient spacing. When cleaning the decking, dirt, pollen, and debris can also get stuck in between the tight spaces of your decking boards. Not only will it promote the growth of moulds and mildew, but it can also cause decking boards to warp.

For all the reasons mentioned above, leaving gaps in between your decking boards is critical. It can either damage your decking or preserve its life. Include the correct spaces or gaps between the boards, which can improve your decking’s airflow, water drainage, durability, ease of maintenance and safety. The question that follows is, how do you space your decking boards properly? How can you tell how much space you’ll need to put in between the decking boards?

leave gap between composite decking

How to Space Your Decking Boards Properly

Weather conditions can affect your decking board. In summer, during hot weather, composite decking boards will expand. If there are no spaces/gaps between the decking boards, it can lead to warping, even in extreme cases shifting the decking area from its original position.
Therefore, leaving spaces between composite decking boards will allow for thermal expansion and help the boards to expand freely without touching each other and preventing damage.

The kind of fasteners you use for your decking can also affect the size gap between the decking boards. Composite decking uses a hidden fastener system with options of 3mm to 6mm spacing between the boards. These gaps take into consideration that the decking boards and substructure are correctly installed to the manufacturer’s specifications.
For wood decking, the recommendation is to use screws instead of nails to hold the wood decking boards in place. Screws will grip the decking stronger, thereby keeping the board in place when it expands and contracts.

There are two types of spacing for your composite decking boards, namely side-to-side spacing and end-to-end spacing. For side-to-side, you will need to put anywhere from 3mm to 6mm. As for the end-to-end spacing of composite decking boards, you need to have 6mm to 8mm.

Installing Decking in Hot or Cold Weather Conditions

As previously mentioned, weather conditions do matter when determining the installation and gaps between the decking boards. If you are installing in the summer, it is important to allow the boards to climatise to the weather conditions at your location by allowing up to 48 hours for this. This means in hot weather the decking boards will expand. During installation, you can leave a 4-6mm gap end to end as the boards will have most likely expanded in warmer weather conditions.

In cold weather conditions, the reverse happens. The decking boards will contract and shrink, leaving a larger gap of 8mm plus end to end is a must. This will allow the boards to again freely expand during the summer months. Hopefully, this will arrive sooner here in the U.K. If you decide to install below 0 degrees, then a larger gap upwards of 10mm would need to be included. Please note many suppliers and manufacturers will advise against installing composite decking in very cold conditions.

Of course, not all composite decking boards are equal. Because of this, you will need to consider how you’ll space the decking boards. To include how large the gaps between the decking boards need to be. One of the things that you should also consider is how much the decking boards will expand and contract (shrink).

For instance, dark colours such as grey composite decking boards absorb more heat. When it comes to thermal expansion, they can increase in size faster than lighter-coloured boards.  Depending on the brand you’ll be using, some may be more susceptible to expansion than others.

Lastly, when you are installing composite decking, you may need to consult with the board’s manufacturers. They can give you clear and concise instructions on the building process, including how much gap you will have to put in between the decking boards. Some installation guides may not even require you to put spaces, especially considering how excellent composite decking materials are.

In any case, placing gaps between composite decking boards can either make or break your decking. So you must remember to follow any instructions on how to do them properly.

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