I applied on a patio floor under a deck. I tried with a roller but It would have been too much work because the product is really watery. I ended up running to get a pump and I used that. I contacted costumer services several times and they were great help. It seems that I over applied it in some areas so I got some staining. The product itself is great, you can see the water on the surface after a rainny day. I haven't applied it on the whole patio and you can see and feel the difference between both sections.