Fitting shelving to a chimney alcove

[diywife]

My husband is making bookshelves to go in our chimney alcove, but we can't attach anything to the back wall as it has a 52mm soundproofing 'soundstop' board on it, so we have to rely on using the sides of the alcove only. The alcove is 86 cm wide. Any suggestions as to how he can do this so our shelves don't sag. He want to make it out of thick MDF so we can paint it white. Could we attach a rear batten using extra strong adhesive such as 'pink grip'?
Thank you for your help.

[stoneyboy]

diywife,
Books are notoriously heavy so you will need to add vertical supports down through all shelves and onto the floor.
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[diywife]

Thanks for that, so if he put side panels attached to the sides of the alcove, and put bookshelf type strips on each side to rest the books on, that would be ok? (sort of like making a bookcase but without the back, but with the sides supported by the alcove walls and the floor unit below (they are solid, not partition, and are v hard to drill into, so they should hold it up!) Thanks again.

[stoneyboy]

diywife,
I'd recommend a central upright as well to stop the shelves sagging.
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