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    Do You Need Gaps Between Decking Boards?

    18th September 2023

    When installing decking in your garden, one of the key considerations is whether or not to leave gaps between the boards. This seems like a simple question, but the answer is actually more complex than you might think.


    Why gaps are often recommended

    Many decking manufacturers and installers recommend leaving small gaps between boards - usually 3-5mm. There are a couple of reasons for this:


    Allowing water drainage

    One of the main reasons to gap boards is to allow rainwater to drain through the gaps so it doesn't collect and pool on the surface. This helps prevent rot, mould and slipping hazards.


    Accommodating expansion and contraction

    Wood expands and contracts with changes in moisture and temperature. Gapping boards allows room for this natural movement so they don't buckle or push against each other. This prevents warping and lasting damage.


    Improved aesthetics

    Some people simply prefer the look of gapped deck boards as it makes the grain and texture more visible. The gaps can create an interesting visual effect.


    Potential downsides of gaps

    However, leaving gaps does have some potential disadvantages:


    Can collect dirt and debris

    Gaps provide spaces where dirt, leaves, pollen and other debris can collect. This can create an unsightly mess and cleaning between boards is difficult.


    Increased risk of high heel entrapment

    Heels from women's shoes can become caught in gaps between boards if they are too wide, leading to tripping hazards. Narrow gaps of 3-5mm reduce this risk.


    May allow greater water penetration to subframe

    While gaps allow surface water drainage, some water will still penetrate and reach the subframe. Good subframe drainage is still required.


    Can allow weed growth if gaps are too wide

    Larger gaps may allow weeds to sprout up between the boards. Keep gaps narrow to limit light penetration and discourage this.


    May not suit some board types well

    Some modern decking products such as composite boards expand and contract less, so don't require large gaps for drainage and expansion.


    Key considerations when deciding on gapping

    Here are some tips to help decide whether to gap your deck boards:

    • Consider the climate - in wet regions with heavy rainfall, drainage will be more important.
    • Assess subframe drainage - if this is poor, larger gaps may be beneficial.
    • Check board expansion traits - composite and plastic boards require less gap allowance.
    • Evaluate aesthetics - do you prefer the gapped or closed board look?
    • Assess usage - high heels likely means minimal 3-5mm gaps are safest.
    • Weigh up debris concerns - can you manage cleaning between gaps?

    Overall there are good reasons to gap decking boards, but also some potential downsides. Assess your specific deck, climate and usage to determine if gapping will be right for you. Allowing 3-5mm expansion gaps with good subframe drainage is a good middle ground. But leaving boards tightly abutted can work too if the decking material and regional climate suits this. Consider all factors for your deck to make the best choice. And if you’re looking for decking boards, then look no further than UK Sleepers! 


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