I want to put up a shelf for a microwave, which I guess weighs around 10 kg.

In the UK plywood is marketed as either "structural" or "unstructural". Is "unstructural" a good choice for this application, or should I use structural plywood?

The microwave is I'd say typical microwave size in the UK: about 48 cm side by 36 cm deep. The shelf will be the size of the microwave. I'm guessing I'd use 18 mm thick ply, but I imagine that might depend on the type of ply.

The shelf will be supported by two metal brackets (which have bracing struts that form a triangle). The brackets will be positioned at or within a cm or two from the location of the feet on which the microwave stands, so as to minimize the bending moment on the shelf.

  • 2
    There is not enough information here to answer. Width length thickness of shelf fir starters
    – Kris
    Oct 26, 2018 at 17:44
  • 1
    And it depends entirely on the shelf support type and span.
    – isherwood
    Oct 26, 2018 at 17:52
  • @Kris Don't you think the principles are more interesting than the particulars here? Oct 28, 2018 at 12:56

1 Answer 1


From my reading, unstructural is not ok in damp/wet or areas with temperature changes. Microwaves put out a decent amount of heat and moisture, so I would not use it in this application.

Personally, I like to use solid wood for shelving as it is pretty cheap (pine) and you can normally get it in a size/length very close to what you need.

  • I found it hard to source solid pine/spruce sheeting locally (east London). I guess I don't know where / what words to use to look for the places that sell that type of thing... or maybe it's more usual to join smaller pieces of solid wood for these dimensions? Oct 28, 2018 at 12:58
  • @CroadLangshan while that is on the bigger side; I have no problems with that in the USA. I would typically see multiple boards glue together to make a wider board. If that isn’t an option, I would definitely recommend the structural plywood Oct 28, 2018 at 13:06

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