big shelf

I would make it 3/4” to 1” and face the leading edge with another board…assuming you’ll be putting books on the shelf.

-- jay, www.allaboutastro.com

A shelf that it going to have to support a lot of weight. I would bracket it at every stud and make it 1” thick.

-- Bondo Gaposis

Here’s a fun toy…

http://www.woodbin.com/calcs/sagulator.htm

What you’ll generally find is that support will be needed every 32” minimum. If you attach with a french cleat that will give you additional rigidity.

-- -- Rick M.

+1 on using the Sagulator. Good call, Rick.

-- Art

it may sound over kill but i would use 2×4’s to make the skeleton for it and then cover it with regular white board and a nice decorative moulding,brace it, then paint to your liking.

-- You can get alot further with a kind word and a hand gun, than just a kind word alone

Divide the length by 3 and that is where you should put a support plus at the ends; a total of 4 supports.