# Expansion of wood countertop with built in bookshelves resting on it



## ejww (Feb 7, 2021)

First post. I'm new to woodworking after looking for ways to pass the time over the last year during the pandemic. I'm hooked and maybe being a little ambitious by tackling this project for our den. 

My question is in regards to securing bookshelves on top of a base cabinet. If we were to use real wood for the countertop, how do you account for expansion? I was going to float the countertop with screws and routed out channels perpendicular to the wood grain. But would the weight of the bookshelves resting on the countertop restrict movement enough to cause damage? I planned on attaching the bookshelves to the wall using cabinet screws.

What is the best approach for this?


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## yomanbill (Jul 7, 2020)

Without any fasteners or glue, just the weight of the shelves on the counter top will have no effect. It could have had an effect had you fastened the shelf units down to the top. Likewise for the top to base cabinet fastening. No problem either way if construction is plywood. The best way to fasten tops to case work just depends on the materials you are using and, in the case of solid wood, whether you have cross grain situations.


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## ejww (Feb 7, 2021)

yomanbill said:


> Without any fasteners or glue, just the weight of the shelves on the counter top will have no effect. It could have had an effect had you fastened the shelf units down to the top. Likewise for the top to base cabinet fastening. No problem either way if construction is plywood. The best way to fasten tops to case work just depends on the materials you are using and, in the case of solid wood, whether you have cross grain situations.


Construction will be all plywood with 3/4" maple or red oak from a big box store for the countertop. I'll be looking at other lumber suppliers in the area. But is 3/4" strong enough for this countertop? Should I go with 4/4 or higher? I'd also considered using a plywood subtop with edge banding.


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## yomanbill (Jul 7, 2020)

3/4" maple or oak will be more than strong enough for the counter tops. Just keep in mind that all wood expands and contracts (mostly cross grain) with changes in temperature and humidity. Look into the various ways of accommodating that and you will be OK. Typical devices for this are metal clips, wood buttons, and screws through elongated holes. There are charts that you can find on the net that will tell you how much movement to expect for the species and size you are using. Plywood, because of the laminations, is very stable and does not move like solid wood. Specifically, if you use a plywood sub-top, do not glue the oak or maple top to it. Only use screws through elongated holes so that the screws can slide a bit as the oak or maple moves.


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