![]() ![]() Is this allowable and why or why not? Again this is prescriptive. Rafter ties shall not be spaced more than 4 feet o.c. Ridge boards shall be at least 1 inch nominal thickness with a depth not less than the cut end of the rafter. Rafters shall be framed to the ridge board or to each other with a gusset plate as a tie. They will not be placing the ceiling joists at the top of the support walls, instead they will be raising the ceiling by placing the ceiling joists 24" up from the supporting walls tying into the rafters. Rafter spans shall comply with IRC Tables 802.5.11 through 802.5.58. They will use asphalt shingles and the total dead load will be 10psf. You are given plans for a home with a simple gable roof. With consideration for R802.3 and Table R802.5.1(3), (2006 IRC), based on a common rafter length of a little under 20, it is plausable that 2x10 common rafters attached to 2x12 hip rafter can be used prescriptively where common rafters are 12' O.C. For other grades and species and for other loading conditions, refer to the AWC ST JR. I really hope this becomes a good topic of discussion and we all learn something from it.ĭisclaimer: This is not an actual situation that I or anyone I know currently has, this is hypothetical for discussion/education. For ground snow loads other than those cited in Tables 802.5.1(3) through 802.5.1(8), spans for rafters may be determined using linear interpolation. For other grades and species and for other loading conditions, refer to the AWC STJR. Rafter spans shall be measured along the horizontal projection of the rafter. If you are certified under the IRC with the ICC, you certainly should be able to.Ħ) If you say yes, please explain how you arrived at your answer. In table 802.5.1 of the 2010 CRC, Douglas Fir-larch is listed as SS, 1, 2, 3 and then right below that, (same table), Douglas fir-larch SS, 1, 2, etc. Rafters shall be sized based on the rafter spans in Tables R802.4.1(1) through R802.4.1(8). This way everyone is in the same situation.ģ) We are looking at this from a structural standpoint for the size of a rafter only, energy, and other items not applicable.Ĥ) If you say no, please explain why and cite not only the code reference but how you determined it is not.ĥ) This is a prescriptive question, referring to an engineer/RDP is not an option. Spans for rafters shall be in accordance with Tables R802.5.1(1) through R802.5.1(8). Sorry to be a bit rigid on this:ġ) Either you would approve it on the plans or you would not.Ģ) The question is as is, your local variations, if applicable are not relevant. There are some rules for this so that we ensure it is educational and don't get of topic. Where ceiling joists are not parallel to rafters, rafter ties shall be installed. This is something at any code official would have to do when plans are submitted. I am proposing the anyone who is interested post whether or not you would approve this installation. ![]() I have, what I believe is the correct answer, but you never know. I want to try this out for fun and educational purposes. ![]()
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