How Much Does Wood Contract? Understanding Shrinkage

You’re right to be curious about how much wood contracts! It’s a crucial factor to consider when working with wood. Here’s a breakdown of what you need to know:

Flat-sawn hardwood shrinks about 8% from its fully wet state to completely dry. Quarter-sawn hardwood shrinks only half as much at about 4%. That difference is due to the way the wood is cut.

Flat-sawn lumber is cut parallel to the growth rings of the tree. This means the grain runs across the width of the board. Since the wood shrinks more across the grain, flat-sawn lumber is more susceptible to movement.

Quarter-sawn lumber is cut at a 90-degree angle to the growth rings. This means the grain runs along the length of the board. Because of this, quarter-sawn lumber is less prone to warping and cupping. It’s also more stable and less likely to shrink or expand.

Understanding the difference in shrinkage is important for many reasons. For example, if you’re building a door or window frame, you’ll want to use quarter-sawn lumber to prevent warping. Or, if you’re creating a piece of furniture with intricate details, you’ll want to be aware of the potential movement of the wood.

Here’s another way to think about it: Imagine a wood plank as a stack of coins. If you stack the coins flat, they’ll be more likely to slide around and move. But if you stack them on their edge, they’ll be much more stable. The same principle applies to wood! Flat-sawn wood is like stacking the coins flat, and quarter-sawn wood is like stacking them on their edge.

So, for most projects, it’s helpful to know that quarter-sawn lumber is about half as likely to shrink as flat-sawn lumber. Of course, if you’re working with a particular wood species, it’s always a good idea to check out the specific shrinkage rates. That way, you can be sure to choose the right type of wood for your project and avoid any unexpected surprises!