What’s with the gaps between the deck?

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What is the best gap between decking boards – and are there even tables for this relative to species and board width?

We often have questions or requests from customer stating that gaps between the their timber deck. Some times more difficult customers even insists that we leave gaps much smaller or even no gaps between the deck board against our advice when we begin our deck installation.

“I want no gap between the boards” or,
“I want a 2mm gap between my deck boards”
our reply is usually…. “when?”

Like a stopped watch that is only right twice a day, those deck boards are going to expand and contract as the weather changes and no matter what you do the gap between the boards will only be consistent for a certain window of time. This is why you find so much debate on how to set the spacing between your decking because the answer truthfully is, “it depends”. The only bright side of it all is that we have no snow in singapore and our only battle is against the scorching sun or the intense humidity.

It is a great irony that the bulk of deck building happens when the thermostat passes 30 degree celcius.  The good news to this is that installing a deck during this weather assures you that your deck (or whatever species you choose) is at one extreme of the wood movement spectrum.  In other words, the wood will move, but only in one direction.  During the raining season, the decking is swollen with high humidity. All of those wood fibers are like a bundle of straws and they have sucked up the moisture in the air, expanding the board width.


In an example we found overseas…

Each species will have different movement properties but for composite. If we install a typical 1×6 Ipe decking board today using our weather conditions of 90% humidity and 96° and assume the wood is 5.5″ wide. It will maintain that width through the heat and humidity but as we draw into fall and they both begin to drop. If we pick a day in early October and assume 50% humidity and 65° then the Ipe will have shrunk approximately 3/16 of an inch. Now your starting 1/4″ gap is almost a half inch wide and someone just got their heel stuck between the boards at that swanky dinner party.

Fast forward to the dead of winter and the temperature is now 25° and the humidity is around 25-30%. Your decking has now shrunk another couple of 16ths and that half inch gap is closer to 5/8″. Now your Chihuahua just fell through the gap between the deck boards!

That widening gap will make any deck owner upset but now imagine the opposite scenario where the deck was installed with a 1/4″ gap in the dead of winter. By summer time those boards have expanded by more than 1/4″. In a perfect world we can assume even expansion in both direction so each board would swell 1/8″ on both sides. If you are lucky that original 1/4″ gap is gone. In reality boards don’t always expand evenly and it will vary depending on where the board was located within the original log. Usually the boards expand beyond that 1/4″ gap and now the boards are buckling and possibly cracking since they have no place to go. This can result in serious damage and the need to replace decking as well as soothe the anger of your customer.

Just to make thing even more difficult, wood is anisotropic. It moves differently in each direction and will vary on how the wood was cut. Quartersawn boards barely move across the width where flatsawn boards will move the most (the examples above use flatsawn boards since this is most common). Now not only will the gap change but it may not change consistently across the entire deck.


So How Do I Space My Boards?!!

What is the solution you ask? How to stop the madness? You can’t stop it. Wood moves, get over it. Embrace it and plan the gap between that decking accordingly. You still want a little gap just to let rainwater drain through. With no drainage comes standing water and a whole new set of movement issues. We ran some numbers and figure out just how much that decking is going to expand and contract throughout the year so trust us on this.




Hong Ye Eco

You will be pleasantly surprised how Superior quality Timber Decking can enhance your patio/balcony area into a spectacular outdoor living area. With our creative custom made decking designs, your decking area will become a remarkable feature of your premises, forming a sense of wide open areas that embraces the outdoors. As one of Singapore’s leading custom built decking experts, we pride ourselves on our professionalism and reliability, attention to detail, from the preliminary design appointment right through to the completed product. We believe that clients come first, making sure that we attend to all of your expectations and requirements.

Constructed to the highest possible level of quality requirements, we only use the best construction materials, specialising in select grade Chengal, Ironwood, Heveatech, or Teak decking as we can guarantee when using this timber you won’t have any issues with warping, cracking or splitting of timber decking boards. We have been building with this timber for many years and highly recommend using our timber decking. Make a scheduled appointment today and we’ll provide you with the ideal decking solution to suit your home, lifestyle and budget… that is constructed to last.

It has been proven, that HongYe’s workmanship is outstanding. You can check out our gallery to see why our customers are very satisfied and why they are willing to recommend us to their friends.



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