Our beautiful flagstone patio was installed 1.5 years ago. The hardscaper said no to my request to seal it. He said it was unnecessary and I would just be wasting my money. Since that time, I have seen what look to be permanent stains here and there. Stains left from lawn chairs, tiremarks from a commercial lawnmower (almost gone after treating with baking soda), and stains from natural droppings from the sky just to name a few.

Is there any reason it should not be sealed (any disadvantages)? It looks like it will eventually be ruined from stains if I don't seal it. I am thinking that sealing will preserve the clean new look before it becomes unsightly.

I would really appreciate any suggestions. Thank you.