How much do books weight?
Why would you want to know?
Well, at work (www.rootskitchens.co.uk) we are frequently asked to supply book shelves. Remembering that every book is different, a typical selection of cookery books (at least, the selection I had to hand at the shop) weighed a total of 2.25Kg and occupied 100mm when standing on edge. Therefore, 1 metre of books would weigh 22.5Kg and our shelves and (when rounding) brackets would need to support a minimum of 25Kg/m.
Remember though, that's a minimum because:
- their books may weigh more
- they may stack books on top of books
- their books may be shallower than their shelf and all on the front edge
- suddenly find a new home and be replaced by heavier cast iron sausepans
Shelf brackets (decent ones anyway) will state how much weight they have been tested to safely hold. This is normally given as an evenly placed load around the mid point of the bracket. For example, if a given bracket will support 20Kg and is 300mm long, the 20Kg is taken as acting from the middle - 150mm away from the wall. Therefore if you put all of your 20Kg weight at the far edge, 300mm away from the wall you can expect the bracket to fail.
Also be aware that some brackets give Safe Working Load when used as a pair, whilst others will be based on each individual bracket. Remember your shelf also has a weight and you may need to take this into account.
As a rule of thumb, if a customer says they would like to use a shelf for books I would look to find brackets that would support a minimum of 35Kg/m for a shelf 300mm deep. Therefore a 500mm long shelf would need to be able to hold 17.5Kg, and so on.
The other thing worth thinking about is bookends - some of those can be heavier than the books! Perhaps you can find some that can be permanently fixed to stop books falling off.