How to Widen Deck Boards Gaps | Fix Tight Deck Boards

I wish we’d done this earlier because it’s actually really easy to widen deck boards gaps – I thought we’d have to do major work to fix tight deck boards.  If you’re struggling with no space between deck boards, but are wondering: how do you widen the gap between deck boards?, read on to learn how to cut space between deck boards – plus the simple hack that makes sawing between deck boards foolproof.

What Happens if You Don’t Space Deck Boards?

If your deck boards are too close together, it can lead to wood rot, shortening the lifespan of your wood deck.  In addition, deck boards need room to expand and contract, and without this space the wood can start to buckle or crack.  When the original owner of our lakehouse built the deck, he really pushed the deck boards close together.  Or maybe the decking boards expanded after he built it?  Either way, not having a space between deck boards caused problems.  We didn’t have issues with wood rot or buckling, but water could never properly drain from the deck.  In hindsight, this should have been obvious to me because the deck was covered in mildew when we bought the house:

When we first bought the house and saw the mildew, I didn’t realize that a lack of space between deck boards was the problem.  In 2014 I scrubbed the deck thoroughly, prepped for staining, and stained the deck grey.

I was disappointed when, a few years later, the deck stain didn’t hold up.  In 2018, a lot of the stain had just worn off and the mildew was back:

So I scrubbed it again and applied an opaque black stain.  By this point, I suspected the deck boards were the problem.  I had been wondering, “should deck boards have a gap?”  Turns out – YES!  Deck board spacing is so important.  But I thought it would be such a huge job to widen the deck boards gaps.  I hoped that if maybe, I got better stain, it would be fine… Plus we were getting the exterior renovated at this time, so it was a scramble just to get the deck stained before the snow fell.

By 2021 the deck looked like this (I snapped this photo after we widened the gap between deck boards, to show you how the deck stain wore off):

We finally decided to widen the spaces between the deck boards, before staining it black again.  I sanded any loose and peeling bits of stain with an orbital sander while hubby went about widening the deck board gaps.  Here’s how we increased the deck board gap without removing the boards – and how you can easily widen deck boards too!  If you’re wondering, “how can I increase deck board gap without removing the boards?”  read on to learn how to fix deck boards that are too tight.

Supplies to Widen Gaps Between Deck Boards:

• Circular saw
• Screws
• Plywood Scrap

You don’t need to remove the deck boards to widen the gap between them!  Just take a circular saw and cut in between the boards.  Sounds scary, right?  Envisioning yourself veering off course and destroying the deck?  All you need is a makeshift guide to keep the circular saw in line!  I’ll explain how to make a saw guide in the next section, but here are the basic steps to increase the space between deck boards.

How to Widen Deck Board Gaps:

• Clean the deck crevices of debris, using a broom or leaf blower
• Hack your circular saw with our easy and inexpensive DIY saw guide (see below for instructions)
• Put on knee pads and hearing protection
• Adjust the blade depth to cut through the crevice the entire board depth – but not so deep that is cuts the cross pieces under the deck boards
• Then simply run the circular saw between all of the deck boards

How to Make a Saw Guide to Widen Space Between Deck Boards:

You can buy a saw guide; there’s a circular saw attachment sold online as a simple solution to widen the gaps for decks with boards that are too close together – but you can save money and try this simple hack instead.  Hubby already had a piece of plywood attached to our circular saw (he got it from his dad like that).  You can see in the photos that it is just screwed on.

With this plywood base, which you can easily make with a scrap of wood, we were able to add a single screw in front of the blade, screwed down to just short of the depth of the existing groove:

That simple hack acted like a guide as hubby slid the circular saw along, to make sure the saw didn’t go rogue and cut across the deck boards.  You might have to adjust the screw depth if it gets caught on bits of stuff jammed in the crevices.  But this little hack worked just as well as any saw guide for widening the space between deck boards.

How Much Spacing Between Deck Boards is Needed?

Research suggests that the proper spacing between deck boards should be approximately 1/8″.   An afternoon of cutting, and we now have the proper 1/8″ gap between all of the deck boards:

What Kind of Saw Blade to Cut Spaces Between Deck Boards?

First, use a new blade or this will take forever.  Hubby tried it with some older blades and was not getting anywhere, so we bought a fresh blade and the job went so much more quickly.  For blade choice, many different saw blades would work.  Hubby picked a blade with a low tooth count (40) because it cuts faster – although it does make a slightly rougher cut.  This didn’t need to be a fine cut (like for furniture or fancy projects).  You can see the cuts aren’t perfect but we felt that fast was better than perfect for this job.  When I was sanding the deck, I could have sanded those edges too, but we just want this project done so I can put our patio loungers back.

How Long Did it Take to Widen the Deck Boards Gaps?

We thought this task would take days, which is why we avoided it, but it took hubby only a few hours.  Of course, the size of your deck makes a difference!

Did Widening Deck Plank Gaps Make a Difference?

Already I see a huge difference!  We definitely have a nice 1/8″ gap between all of the deck boards now and water can drain.  I notice after it rains, the deck no longer stays wet for days – it dries so quickly now.

Here’s a before and after:

The deck dries so quickly now after it’s rained or washed.  And it seems like gunk doesn’t pile up in the crevices between the deck boards anymore.  But I am going to try to use my leaf blower more to make sure the bigger pieces don’t sit in there.  We get a lot of pine needles and the like covering our deck, so I need to get better at keeping it clean.

Next Steps…

I finished sanding any loose bits and managed to apply a clear deck primer since taking these photos, but now it’s been raining so often I can’t finish staining the deck.  Ugh, this happens every year.  I hate deck staining… I chose a black stain again and hopefully the deck primer makes a difference in how well it withstands the elements.  I didn’t sand the deck down completely because the deck primer/stain I’m using doesn’t require it – but my father in law, a woodworker by trade, is dubious of my plan, lol.  Once the weather cooperates, I’ll share an update on the finished deck and also again after we’ve lived with the new widened deck boards for a bit.  Fingers crossed I can take a nice long vacation from deck staining now that we figured out how to widen the deck boards…

Hopefully this is helpful for anyone who needs to fix tight deck boards.  Don’t delay, like we did, because deck boards that don’t have gaps can cause major damage to the wood.

UPDATE

Here’s the finished deck, in a quick little video I shared on Instagram:

 

 

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A post shared by Tanya | Decor, DIY & Thrifting (@danslelakehouse)

 

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