Do You Leave a Gap Between Composite Decking?

Henry A

Deckings are a must for many households. It provides a space for entertainment and relaxation, increases your home’s kerb appeal, and adds value to your property. One of the most popular decking options today is ultra decking. Ultra decking composite board has an inherent resistance to weather and moisture. To save the cost, many homeowners install their decking themselves. But during the building process, one question can come up; do you need to leave gaps between composite decking boards?

Gap Between Composite Decking

Why Leave Gaps Between Composite Decking 

Whatever decking you are installing, you will almost always need to put spaces between the boards, both side-by-side and end-to-end. How much space you would need between the decking boards depends on many factors. Some manufacturers will give you detailed instructions and guidelines that you should follow. With that said, there are several reasons for spacing out your boards. Here are some of them.

Thermal Expansion 

Traditional wood decking boards expand and shrink under changes in humidity and water content. Composite deckings, while resistant to moisture, swell and shrink for a different reason. When exposed to heat, composites expand. And then the boards contract when the temperature returns to normal. Putting space prevents any friction between the decking boards due to the constant shifting.

Thermal expansions also cause other problems for your decking. The constant shifting may damage the fastening systems, leading to structural failure, high repair costs, and dangerous accidents.

Easier Maintenance

Another reason why you want to put gaps between boards is to make maintenance easier. One of the potential problems of deckings is water pooling. Not only can it cause slips and falls, but it can also cause moulds and mildew, especially when paired with debris and dirt. Without any deck spacing, your decking is more susceptible to water drainage problems. The only reason why you don’t want better drainage is if you have raised or second-floor decking.

Besides water pooling, it’s also easier to clean decking with board gaps. Debris will fall off between the spaces as you sweep. As mentioned, dirt and debris contribute to fungi growth and rotting. However, you will want to put enough space between the boards so debris won’t get stuck between them.

Sufficient Ventilation

The decking boards are not the only part of the deck you want to protect. The frame and everything underneath is as crucial as well. Like the decking boards, the decking frame will also need air to breathe. They also expand and shrink, and they will need proper spacing to have ventilation to allow breathability. Besides structural damage, moisture under your decking can also cause moulds and mildew.

However, spacing the boards too far from each other also has a few disadvantages. Doing so makes the decking more susceptible to fire. Wide decking board gaps can also be dangerous, causing trips and slips.

Always Space Your Decking Boards

gap between decking boards


In conclusion, decking board gaps are crucial details you shouldn’t overlook. In almost every case, you will need to put spaces between the boards for three primary reasons; thermal expansion, easier maintenance, and proper ventilation.

If you put enough space between the boards, you can prevent damage to the boards caused by shifting due to thermal expansion. You can also clean your deck faster and protect it from water pooling issues. And lastly, you’ll reduce mould and mildew growth by providing decking ventilation.

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