Fitting wall mounted bookshelves...what do I need to know?

[IToldYouIWasFreaky]

I need to free up some space in DS's room and want to replace his freestanding bookshelf units with wall mounted shelves. I quite like the look of the Ikea Lack shelf (floating shelf) but I am concerned that they won't be able to hold the weight of the books...especially important as I am planning some shelves to be above his bed and don't want them to come crashing down on him!
Any advice for some good weight bearing shelves and how to fit them?

Not floating shelves but I have just used twin slot shelving in my living room for a very large number of books you can then use any wood painted /stained as shelves to get the look you want.

Twin slot can look industrial but behind the books you don't really see it

I wouldn't put floating shelves full of books over a bed, Books are incredibly heavy.

twin slot are brilliant though- lots of pics on Pinterest of them looking very chic and cool.

We have the la k shelves with the end metal brackets. So not entirely floating, but not fully supported either. They take 10kg per shelf. We use them for books so have made sure not to overpack them and they're fine. They've been up for nearly 3 years with no problems. Ours are above the TV so if they collapsed we'd be needing a new TV! I think they'd be fine above a bed as long as you check the weight they can take...

These are ours: www.ikea.com/gb/en/products/storage-furniture/wall-shelves/ekby-bjärnum-ekby-mossby-wall-shelf-stainless-steel-aluminium-spr-99119608/