Have you considered just building the wood frames for the shelves, then taking the shelves to a glass shop and having them install the glass. My husband built the bookcases around our fireplaces. Since I have so many books we decided to install glass to prevent sagging. Has held up very well and light from lamps is able to shine thru. Best of luck to you both.

why don't you use a plywood w/a oak (or any other type of wood) veneer? this is a 3/4" white oak veneer plywood. you can stain any color.

This is an example.

then for your trim pieces, use the solid oak pieces for the outfacing edges.

IF you want to paint, then use a poplar or another paint grade quality plywood.

We used a walnut plywood to make a platform bed.

Or, try Plyboo. it's more expensive than the other plywood, but it's really strong.

it's made from bamboo. We used two sheets of it to make our own bed and two nightstands.

we've had this for well over 12 years now.

there's never been any sagging or warping. this Plyboo comes in a 4x8 sheet and costs (then) about $200. I stained it and put a clear coat finish on it. it's held up beautifully.

thank you for the advice!I will see what I can find in my local lumbar yard... rwiegand thank you for your helpful advice!

Sagulator is a good tool.

That said, deflection strength is dependent upon shelf width and depth. But it's also very dependent upon shelf thickness. Strength in thickness is proportional to the cube (third power) of thickness distance. So a shelf that is twice as wide will have twice the resistance to sagging. But one that is twice as thick will have _eight times_ the resistance to sagging. Or one that's just 25% percent thicker will have almost twice the strength. This is why the rwiegand's advice to put an element at front (and back) of shelf is excellent advice.

but if I want the shelves to be adjustable I don't think reinforcing it this way will work...is there another way that you would recommend?

Several years ago, my partner and I built 11 ft of floor to ceiling bookshelves at my previous house. We used 3/4 inch cabinet grade birch plywood for the uprights and the shelves and then added a trim piece as shown above to the shelf fronts. We actually did that for the look more than the strength as it was the easiest way to make the shelves look substantial. I had the bright idea to measure a standard paperback and use that height for setting the distance apart for the shelves. However, I based my calculations on the distance between the plywood portions, not counting the decorative front pieces. Once in place, the books had plenty of space but I did have to insert them in just a certain way to get them to fit under the edging piece.

I drilled two columns of holes in each of the uprights for shelf pegs. After I finished marking and drilling the holes, I decided that I would buy the predrilled plywood pieces if I ever decided to build any more such shelves. My original decision was based on the predrilled pieces were only drilled from one side so side by side required two uprights. Having built them once, I now know to just drill each hole through to the other side in the center pieces and only use one per section. In each section, there was one fixed shelf and the remaining ones were adjustable. Because the shelves were going in a basement, we built a base of 2x4s faced with cabinet toe kick plywood then attached a 1.5 inch trim molding at the bottom. If the basement were to ever flood, water would have to be 5 inches deep before it started to damage the main portion of the bookcases.