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Does Plywood Need an Expansion Gap? (Explained)

does plywood need an expansion gap

When it comes to woodworking projects, the expansion gap is considered a must have to prevent damage to the wood. But, does this apply to composite boards like plywood?

Even with its unique structure plywood, like any other wood product, requires a certain amount of space between boards in order to prevent the natural expansion and contraction of the wood from damaging the structure of the boards, or the overall wood surface.

But what kind of expansion gap does plywood need? Keep reading, and we’ll look into expansion gaps for plywood.

Does Plywood Need an Expansion Gap?

Plywood is like every other wood, in that it needs room for an expansion gap to be factored into construction projects using it.

According to experts like the APA, the quality of the wood may influence the size of the gap needed, but a minimum of 1/8ths of an inch is recommended.

What Is an Expansion Gap for Plywood?

An expansion gap is the space left between boards, or between the edge of a board or another surface, such as a door frame or a wall.

Wood naturally expands and contracts in response to heat, cold, and moisture, and the expansion gap is calculated to take these natural changes into account when laying down flooring, or similar projects.

How Large an Expansion Gap Does Plywood Need?

The recommended expansion gap varies based on the style of the plywood connections.

Between 2 edges and joints, APA recommends a gap of at least 1/8th of an inch

For tongue and groove joints, the recommended expansion gap is between 1/8th and 1/16th of an inch, depending on the style of the tongue and groove.

For the spacing between plywood and wall baseboards, a larger gap of between 1/4 and 1/2 an inch is recommended to give an extra margin of error.

Why Is an Expansion Gap Important in Plywood?

The expansion gap allows for the natural expansion and contraction of wood.

With heat and moisture, wood will naturally expand. Without an expansion gap, the wood may buckle, warp and break.

An expansion gap preserves the integrity of the wood, and the overall integrity of the project as a whole.

Factors That Affect The Size Of The Expansion Gap:

There are several factors that can affect the size of the expansion gap. Factors include:

  • The quality of the plywood itself
  • The regular local variations in temperature (heat and cold expansion and contraction)
  • Local area levels of humidity (expansion due to liquid absorption)
  • The way the wood is cut
  • The style of the joins
  • The size of each panel (expands approx. 0.0000034 inches per inch per degree Fahrenheit

How to Properly Install Plywood With an Expansion Gap:

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There are several recommended methods that can be used. The most important aspect is to properly measure the gaps between the plywood panels, as well as around the edges.

Experts recommend using an 8d or 16d sinker nail to mark the gaps between the board, as the width of the nail is about 1/8th of an inch. Whether this trick is employed or not, steps include:

– Measure 1/4 to 1/2 inch around the edges of the room if you’re laying out a floor, to leave a proper expansion gap between wood and drywall.

– Lay out your plank, and set a mark for each 1/8th inch gap between edges however you see fit

  • For tongue and groove, you may use 1/8th or 1/16th gap for the tongue and groove, depending on the style of construction.

– Stagger the planks across the joists or supporting structure so ends are not all laid in a row. Ideally, stagger by several inches.

– Secure the planking with recommended nails or connecting materials.

To check the current price and availability of sinker nails, click here to view the selection on Amazon.

Troubleshooting Common Problems With Expansion Gaps In Plywood:

Sometimes expansion gaps, or the lack thereof, can cause problems. And fixing these problems can be a bit tricky.

What Are Some Common Problems With Expansion Gaps In Plywood?

Some common problems with expansion gapping include:

  • Lack of gap causes buckling and warping.
  • Too much gap causes unevenness and movement
  • Movement causes gapping or damage
  • Miscalculations due to conditions during installation

How Can One Troubleshoot These Common Issues?

Each of these issues has different methods to combat it.

Lack of Gap Causing Buckling or Warping:

If a lack of gap has caused buckling and warping, the best option is to remove and replace the wood that has been damaged. If you do choose to do this, make sure you have the appropriate gaps installed when you complete the replacements.

If you don’t want to replace the wood, you can try trimming and compressing it back into proper shape, as well as fastening it more securely, but this isn’t the best option.

Too Much Gap Causing Unevenness and Movement:

If the gap is too large, then it creates more of a groove or a ‘break’ in the surface which can create a safety hazard, especially with floors. If the wood is not securely fastened, it can also shift, and make the gap even larger.

The recommended fix is a more secure method of fastening. You can also add a compressible filler to close the gap and provide a greater level of support and control.

You may also add wood plugs, though you’ll have to make sure they have room to expand and contract.

Movement Causes Gaps or Damage:

If your gaps are too large, or the fastenings are not secure, you may have trouble with the boards shifting, which can cause damage. If the damage is too severe, you’ll need to replace the planking.

Otherwise, you can add filler, and a more secure fastening to solve this problem

Miscalculation Due To Conditions:

The best way to handle this problem is to avoid it entirely, Before you secure your planking, double check the following:

  • Have you measured and double-checked your gaps?
  • How humid is it? More humidity = smaller gaps needed at installation
  • How warm is it? Higher temperature = use smaller gaps.

If you have miscalculations, you may wind up needing to trim your planks, add filler, or replace certain sections as conditions change

Final Thoughts:

If you’re installing plywood as a floor, or subfloor, or using it in another project, don’t forget to add your expansion gap. Using an expansion gap ensures that the planks can react to environmental changes without damaging the wood.

Depending on the project and position of your planks, you’ll want between 1/16th and 1/2 an inch gap between edges and different panels.

Measure carefully, and the result will be an excellent floor with plenty of give and expansion to weather even the most troublesome weather for your plywood.

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