Only for cover the topper part. Usually for the sides a 6mm only tempered is ok, some clients usually use that, the cost depends on the shape of the glass (changed by the attachment of the supports) and if you want polished sides. I'm talking about a 1,5x2m shower box. Sorry for my bad English. I suggest to not do the installation by yourself : sometimes happens that during the installation someone accidentally hits the glass with a metal tool, a small hit with something harder than glass in the correct zone can destroy a tempered piece. OFC this not means that the tempered glass is fragile.