Professionals and Amateurs Together

Summer Swelling

Question

Summer Swelling – Why do drawers and doors get tight (hard to open) or stick in the summer? – Anon

Answer

Joe Barry replies: Think of wood as a sponge. In the summer the air is more humid and it absorbs moisture and swells. In the winter the drier air causes it to give up moisture and shrink. A finish only slows the exchange of moisture with the atmosphere – it can never fully seal out moisture exchange. A house with humidity control will lessen the movement. However, few of our customers will have a museum grade environmental control system. We just need to allow for this when we build.

You may have heard the expression “a nickel and dime fit.” One meaning of this expression is that when fitting doors or drawers in the winter when the wood is driest, allow a nickel sized space. Conversely, allow only a dime space when the wood is at it’s largest dimension in the summer. Experience in your shop and with different species will give you a better feel for just how much allowance is required.

Herm Finkbeiner replies: Drawers stick because wood gets bigger in the high humidity of summer. For a very graphic explanation of the phenomenon, see the web site:

http://timber.ce.wsu.edu/content.htm Click on “Moisture Effects” then click on “Next”.

Tags: Wood