The ridge is constructed as a beam that runs from end to end. The rest of the roof framing then follows suit.Ī roof with a ridge beam can be more easily understood if it's imagined to be a flat surface-like a deck in plan view. They're most easily identified by the type of ridge used: either a ridge beam, which is a structural or load-bearing member, or a ridge board, which is a non-structural framing member. But when it's boiled down, there are essentially two standard methods of roof construction, each having some flexibility. Understanding this history provides perspective on why the treatment of roof construction in the IRC and the associated Wood Frame Construction Manual(WFCM) allows for such broad interpretation. Combining these disparate styles and standards into a single code-the International Residential Code (IRC)-was no easy feat, and seemingly fundamental aspects of roof construction are still up for debate. Between the Eastern and Western codes, there were even different names for identical parts. In the past, methods described by the three main building codes (BOCA, UBC, and SBC), though similar, differed based on climatic factors-such as expected wind and snow loads-local habits, and available materials. You could also be benefiting from "real 2x4's", not today's 1.5"x3.5", and the greater strength of old growth lumber, but I can't imagine 2x4's spanning 15' that are unsupported by other framing structure.įor reference, look at Fine Homebuilding's video on YouTube where a Shaker shed that is only 12' in width is built using 2圆 roof rafters plus they used collar ties every 4', that are not shown in the video.Long before any building codes were published, conventional roof framing methods developed through practice, resulting in approaches to roof framing that are as varied as the framers themselves. If you could post a picture showing how your house is framed, that would be very interesting. I don't know how your roof is constructed to have 2x4's spanning more than 15' on 24" centers, but there would have to be additional framing supporting the roof that effectively reduces the distance that is spanned. snow load, the 2x4 roof rafter span drops to 8'5" and 9'0" for Douglas Fir-Larch and Southern Pine respectively.įor the 10 on 12 pitch you're talking about, the span is more like 15'7" depending on details, such as the ridge board and wall thicknesses, so 2x8's should work at 12" on-center. for Douglas Fir-Larch #2 or Southern Pine #2 for 10 Lb. Just basically need to know if my spacing should be 12, 16 or 24 inches.Ī 2x4 roof rafter span is limited to 10'10" with 12" on-center spacing. Again I would prefer to use 2×4’s but can go with 2×6’s if I can’t get away with 2×4’s. I plan on putting on a metal roof so just furring strips + 28 ga metal for live load weight. My building will be 24ft wide with each rafter side being 17′ 6″ long if I calculated it correctly based on a 10/12 pitch with an 18″ overhang. So it would be the standard KD WW that the big box stores carry. I would like to frame with 2×4’s now that the price of lumber has come back down. Being in the southern part and based off recent history I would lean more towards the 15. First I live in south central Kansas so my snow load is 15 – 25 psf. Here are some of my details that I hope someone can help me figure out what i need. They still have the one by furring + decking + asphalt shingles and it doesn’t seem to budge an inch when is snows because it doesn’t hold much snow with that pitch. Our home roof is 2×4 (probably SYP) that is spaced at 24″ or more. I am wanting to put up a carraige house to match our Victorian home that has a 12/12 pitch roof(s). I don’t want to under build nor do I want to overbuild. I can’t help but think that the requirements would be different for a 10/12 or 12/12 pitch roof. I know there are a ton of rafter span calculators online that either give you info for under 3/12 pitch or over 3/12 pitch. I did a quick search on here but coulnd’t find a thread that fit my situation.
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