Red Ridge Wine Cellars Hi capride,
We build custom furniture and when we come across shelving that specs wide open shelves there are 3 things that you can do.
1. Put a row of shelf support pins down the back just the same as
down the sides. On 60" wide shelves that would mean a support in the middle at 30" which will eliminate 80% of possible sagging.
2. Use a solid hard-wood strong-back along the front at least but if you want to be sure do it along the back as well. 1-1/4 -1-1/2" high by the shelf length will not increase the thickness too much while allowing it to stand up to whatever weight you put on it.
3. Finally when we are doing contemporary style furniture we often double the thickness of the shelf to 1-1/2 or even 2 inches. We often use a hollow box style with 1/2" tops and bottoms with glued 1/2"-1" hardwood strips inside every 8-10" as well as keeping them in from the edges by about 3/4". This allows you to place the shelving over top of the shelf pins which gives a modern floating shelf design look and will hold up under any weight.
Hope this help a bit,
Greg

Red Ridge Millwork & Design Ltd.
greg@redridgewinecellars.com
http://www.redridgewinecellars.com
http://www.allreclaimedwoodfurniture.com

Daniel If you look closely, in the middle of the shelf spacing books are placed horizontally from bottom to top. I would venture to say the books themselves are acting as the center support.

The Shabby Nest Valspar's Twilight Purple is similar to the cabinetry. Valspar's High Speed Steel is similar to the wall color, and Benjamin Moore's Fresco Urbaine is similar to the ceiling.

Lompier Interior Group After having to shield inlaid parquet. In any case, this interior is a solution to best.