Advice building library bookshelves (real, not virtual)

I have a huge empty room that I am renovating to be a library/study. I am looking for some advice about shelf heights.

The more technical details are, I will have roughly 4.5m of length around the room for bookshelves. They will be of the style that is a bookcase above a cabinet, so the shelves will start 750mm above the floor, and reach the full ceiling height of 3400mm, with a ladder to reach the higher shelves.
So a whole lot of shelves,

I want the shelves to be fixed, so I am trying to work out shelf height to maximise book storage (I hate my store-bought bookshelves that have so much space between shelves that I can fit two small books on top of each other.

Does anyone have an advice?

(wasn't sure where to post this, hope I found the right place.)

>1 alsocass: There's a group dedicated to built shelves, which has some threads already you might find helpful
https://www.librarything.com/ngroups/611/Bookcases-If-You-Build%25252FBuy-Them-T...

>2 SandraArdnas: Thank you, I looked through the groups before asking, but could find nothing (I did find Shelfarians, but that seemed unrelated!!) :D

I know you said fixed shelves but I strongly advocate for adjustable. I shelve my books alphabetically by author and my collection has grown over the years so I have reorganised them several times in the last decade and a half. Since (despite my best efforts (to buy mmpb/ the same format in a series)) book heights vary, I’ve had to adjust my shelf heights a few times too.

If you’re you’re determined to have fixed shelves and you’re not fussed about what order they are in, you could shelve by height and customise your shelf heights to suit. I know one LTer who shelves (I think) by author but shelves oversize books in a different bookcase.

Yeh, I have made the lower shelf of each 'bookcase' 450mm, all oversized books from that section can drop to that shelf.

If your shelves are being made of wood (wrong material in my humble opinion due to acidic off gassing) either seal them (wish I could remember the name of the product; a good paint store could probably tell you) or place acid free paper on each shelf. That's the poor man's alternative - I fall into that category - like 20 pound copier paper as a lot of brands now do mention whether they are acid free or not on the ream wrapper here in the US.

>6 ulmannc:
Thanks, they are all being painted, not a bit of timber in sight when I am done.

I'm really fascinated because I'm in a very similar situation! Did you build your shelves? Are you happy with them? Would you have done anything differently? Inquiring minds and all.