Our Pocatello, Idaho, home slopes off quite a bit in back. We'd like to use that space to extend a deck from the living room and kitchen and build a small hobby shop with toilet and sink underneath it. I'm sure the plumbing problems can be solved, but what sort of roof is also good for decks? I don't want ongoing roof leaks from snow melt and rain.
Carinne J. ~ Pocatello, Idaho
Hi Carinne, your plan sounds good, but I don't recommend having a roof that is also going to serve as a deck surface. I know you have probably seen lots of pictures of roof top terraces with people lounging and enjoying the view, but I can pretty much assure you that if they weren't already leaking, they soon would be. A flat roof surface is not designed for foot traffic and with all the snow you receive in Idaho I wouldn't think a flat roof is a good idea anyway.
My suggestion would be to do your addition just as you have it planned, but put a shed type roof on it that slopes enough to get the rain and snow off. I would use metal roofing so if anything is dropped off the deck above, it shouldn't damage the roofing and ought to just slide off. Metal roofing should also last a long time so you don't have to access it very often.
Flat roofs are okay for commercial building that are so large there isn't much choice, but I don't recommend them for residential use. I have had to repair too many flat roofs over the years and I definitely wouldn't use one in a snowy area like Pocatello, Idaho.
I would build the deck over the sloped roof of the addition. The side against the house would be several feet over the roof and lagged into your home. The side of the deck away from the home might be as much as five feet over the roof depending on the slope of the roof and how far the addition comes out. That side could still be tied into the addition for support or you might want to cantilever it over so that it just about hides the roof beneath it. I wouldn't cantilever it too much though as you might cut natural light off to any windows in the addition.
You might want to also consider some low maintenance decking material as I would try to keep maintenance requirements to a minimum with both the deck and the addition.
I suggest meeting with a designer or architect in Pocatello and having some drawings done up because if the deck and addition aren't handled right, they might not blend with each other. An architect can come up with a concept on paper and if you don't like it, they can draw another. That's a lot less expensive than starting to build something and realizing halfway through that it might not look so great. You are going to need drawings for permits anyway.