Limestone is porous. It absorbs water. When that water freezes, the stone cracks.

I don't think the issue is freezing with their recommendation to have it covered when used on an exterior. Even if it's covered, moisture can still get to it outside. The website says it is suitable for covered exterior floors in freezing and non freezing conditions. That is why I thought it might be a fading issue.

Well, if it's been resined to fill the pores, the UV will yellow and eventually destroy the resins.

Thank you for the reply, but if you would take a look at Daltile's website, they categorize this stone's soundness as a class A. According to the Marble Institute,
'Sound marbles with uniform and favorable working qualities, containing no obvious geological voids or fissures. They include completely metamorphosed (recrystallized) limestone or dolostone, in which non-carbonate minerals associated with clay and silt have been recrystallized or altered into other minerals. These stones have uniform working qualities, can be used on the exterior or interior, and do not require any filling or patching.'

I don't mean to be rude, but please don't answer my question based on assumptions. I will contact Daltile directly for an answer.

Here is a link that might be useful: Stone soundness ratings

Limestone is porous and will absorb water. It is generally only used on vertical exterior surfaces where the water can drain through, not on horizontal surfaces where the moisture can collect. If you chose to use it in your application, most tile installers would insist that you sign a waiver as it's not suitable for the application intended.

A porcelain lookalike would be your best choice here. You might want to read what the TCNA specifies about that type of installation.

Here is a link that might be useful: Tiling Over Exterior Deck or Balcony

I don't see it as "answering on assumptions," but answering from experience. You can take advice from a salesman or you can take it from an installation Technician with "hands on" experience.

If asked to do this job, I would certainly require a waiver. There are porcelain tiles that look like Limestone without the attendant liabilities, but hey....your project, your house, your money.

Choose wisely grasshopper.........