I'm wanting to add a deck that will come from my front porch and lead to my back deck (that I wanna add). With the cement sidewalk, being where I partially want the deck, do I need to remove the sidewalk first?? I've seen gravel along with cement being used as a support base for the deck supports.....is this right? I was also thinking of having my deck surround a couple of trees.....do you have any ideas on how I can do this without damaging my trees???? I'd greatly appreciate any help you can give. THANK YA VERY MUCH!!!