Allowing for Wood Expansion on Solid Wood Tops

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Wood moves; there’s nothing you can do about it. Even after the tree is down, the wood has been dried, you’ve got it in your shop, and you apply finish, wood is gonna move. It’s a living, breathing thing. If you don’t allow for wood expansion, you’re going to have problems in the future. Problems being cracking, splitting, maybe even blowing a leg and rail assembly apart. Let’s not let that happen.

Do’s and Don’ts

To give solid wood pieces plenty of opportunity for wood expansion, here’s a list of things you should and shouldn’t do:

  • Don’t glue a solid wood top to the rails in the base.
  • Don’t screw the top in place, unless the screw holes have sufficient wiggle room to allow for wood expansion.
  • Do use tabletop fasteners. They’re easy to use, and allow wood movement by sliding along a kerf in the rail as the solid wood expands and contracts.
  • Don’t worry about plywood or other man-made slabs. They don’t have the seasonal movement that solid wood does.

Direction Matters

Wood only expands and contracts in one direction; perpendicular to the grain. Depending on the specie of wood you’re working with, it can move as much as ¼”, or even more. You don’t need to worry about expansion and contraction parallel to the grain.

More Great Info

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Discussion
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5 Responses to “Allowing for Wood Expansion on Solid Wood Tops”
  1. Denis Lock

    To describe wood in your shop as a “living, breathing thing” is totally incorrect. Long before a tree is felled a high percentage of the cells (the heartwood) are dead. The correct description is “hygroscopic”.

    Reply
  2. Arthur Smith (Australia)

    If the applied finish on a surface like the table top used in your demo is also constantly expanding & contracting laterally will the finish not crack with the constant movement eg something like a laquer ?

    Reply
    • Customer Service

      Hi Arthur. Lacquer and other common finishing products have enough flexibility to them that they can accommodate the typical seasonal expansion and contraction of wood.
      Thanks
      Paul-WWGOA

      Reply
  3. Bobbg

    So the question is how much down holding force? Loose so when I pick the unit up the top shifts, or snug enough it won’t move? Basicly how much movement force will a top provide, and I’m sure different types of wood move more depending how hard a wood it is.

    Reply
    • Customer Service

      You want to tighten the fasteners enough so that the top won’t shift when you move it. Even with moderate holding pressure, the table top will still be allowed to expand and contract with seasonal movement. Just don’t tighten them with extreme pressure.
      Thanks
      Paul-WWGOA

      Reply

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