2cm is not "too thick"; just get your details right.

Joseph, not sure what you mean by "get you details right". Do you mean when it is being templated, or in tight corners??

silken1:

Follow the manufacturer's instructions for fabrication and installation. For example, the quartz shouldn't sit directly on the tub, it should have a gap to be filled with silicone to prevent capillary action. These seemingly small details can make or break an installation over time.

What can I use to support the weight of the quartz and prevent damage to the bathtub, when using it as a surround?

We have had the thinner 1 cm quartz for a few years now as tub surround and behind the toilet. I am glad we chose it as it is totally problem free. It's true, unless things have changed, there are less choices and it actually cost more than the thick stuff. I wouldn't recommend the regular thickness. Way too heavy and it juts out too far. The thin is more like a tile would be as far as sticking out. I forget but I think the installers used very thin pieces of heavy rubber (like for windows) or something to set the quartz on the tub. The weight is supported well as it is glued on so the wall is supporting much of the weight. I did complete waterproofing on the wall first also. I think you need a skilled installer and a very skilled person to do the templating. Don't forget to add a grab bar or two. This was done for us but the support has to be installed in the studs before drywall and quartz go on. The quartz guys cut the holes for it and the shower and tap controls. It is a lot of precision work. We also had two niches on one wall which they lined with the quartz and the bottom ledge of the niches were made with the granite we used for our counter. There were several nice marble look ones when we were doing this and they make nice tub surrounds.