I am building a shed roof over an existing deck. I can’t seem to find a table to help me size the rafters. I really do not want ceiling joist but would prefer exposed rafters. The roof will extend out from the house 16′ plus an 18″ overhang. Are there premanufactured rafters that long? if so where can I find the information to determine size. I would have them on either 16″ or 24″ centers and the width of the roof would be 16′.
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Replies
rafters over existing deck
i8'-0" rafters are not uncommon and should be readily available. You do not mention how you are planning to make the connection of the rafters to the existing house/roof. This can often be a problem.
A good starting point might be is to visit your local (real) lumber yard, not big box store. They should be able to advise you as to size and availability. You will also need to size the beam and columns supporting your roof system. Then there is the problem of the deck supporting the column load and their connection to the deck.
A "rafter" is simply a piece
A "rafter" is simply a piece of wood used to support a roof. How heavy-duty the rafter is depends on the span and the load-bearing requirements (eg, do you have a snow load to worry about?).
16 feet is at about the span limit for standard 2x lumber (you don't count the overhang when figuring load). Beyond that you may need to go with "manufactured" lumber. Generally, standard lumber is available in lengths out to 18 feet or so. "Manufactured" lumber is available in virtually any (reasonable) length.
A local full-service lumber yard would likely have people who can tell you what rafter dimensions you need in your area.
HI David, I haven't tried it but I would assume Googling "IRC rafter span table" would bring up what you need. Douglas fir 2x10 spaced 16" on center will make your 16' span. All the local lumberyards in my area carry 20' fir for rafter stock. It shouldn't be hard to come by at all. Good luck
sorry double post