Published at Thursday, July 12th 2018, 14:00:49 PM by Deanna Watts. Bathroom Shelves. The choice of tempered glass shower shelves will depend upon your storage needs and the weight bearing capacity of the shelves. It is always advisable to go for glass shelves with more weight bearing capacity for the simple reason that you may not know what all things you need to store on the shelves. The capacity of a glass shelf to bear load is determined by its thickness and the method of installation. Some manufacturers also offer tempered glass shelves these are made hard especially by heat treatment. These shelves can be chosen if you want your bathroom shelves to bear greater load.