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    hi joe

    just found your instructable and thought awesome cant wait to read this roofing guide but its deleted. Do u think it willl be posted again as im trying to workmout how to build a roof for temporary accommodation. Im in the UK so good news travels far. Big respect for all the effort and time you put into the instructable its greatly appreciated and as to the negative stuff. Any fool can complain.

    1 reply

    Thank you for pointing that out. I'll take down this instructable showing the mathematical one measure one mark way and get that book. Then I'll put up an instructable on how to carry a book around and use the appendix or something.

    How would that be?

    I have deleted this instructable, thanks to instructables user - "whathappened".

    He spoiled it for me, and also for all of you by proxy.

    Everyone give "whathappened" a hand !!

    Thank you so much whathappened; From 520,079 people all over the globe.

    Yay, whathappened.

    3 replies

    I'm deleting this instructable. Thanks to you. I'll wait 1 day then its down. Take a bow...

    I took a lot of time making this, and was proud of it. Your comments made it seem as you didn't even read it, are trashing it with things that are not even in it, and frankly, are inaccurate and poor practice compared to math.

    Did you realize that you are replying to comments that are far beyond stale too??

    If you want to share your "snapping lines all over the floor" way or how to tote a rafters book with you, why don't you make your own instructable instead of ruining one that 1/2 of a million+ people found to be useful or interesting??

    Now that it's down, can you go troll somewhere else??


    Did you even read this instructable??? There is no where that says to "step" anything off. Also, I describe how to take 1/2 the ridge off of the rafter measuring 90* off of the plumb cut. As for all the rest, seems like you want to be an instructable author yourself. So instead of salting other peoples instructables why don't you make your own, and show how to use your book or snap lines all over the floor and explain how much more efficient and precise those ways are compared to a one measure and one mark system such as the mathematical way my instructable shows...


    1. Who said anything about not having $20??

    2. I don't look down on people like you, who like to tote a book around from job to job, why do you look down on folks who like to be self sufficient, and solve mathematical problems for themselves, with knowledge they learned and committed to memory in their own brains?

    And last but not least...

    3. Why exactly, would the math not work, and put a "hump" in a roof??

    4.You did read the title and see that this instructable is on Common rafters, and not on Hip or Valley rafters I trust..

    5. For me, weather a building is a box, rectangle, a circle, or "L" shaped and weather it has a valley, dormer, or nothing at all..... one would think you would be sure your rafters are the correct length. One would think...

    My deck is 66 foot long 16 foot wide how long should the rafters be

    1 reply

    It would depend on the pitch you want to put on it .

    Thank you for all the useful information you have provided in this forum! My question is in using the formula to figure out the length of the rafter, what would the overhang be for a 5/12 pitch? We are trying to get a take off list for the material required. Thank you for your time!

    There didn't seem to be much instruction on how to figure where to mark for the plumb cut meeting the peak of the roof. Everything else made perfect sense!!

    1 reply

    Thank you for pointing that out, I've edited that step giving it more detail.

    Sorry for the late reply Mikeswife.

    Again, I'm not sure how big your roof needs to be, so I'll just try to cover all the bases incase you are building something on the larger end.

    You find that angle by determining what pitch you want your roof to be, or by following your blueprints. Most residential roofs are between a 5/12 (which is a 22.5* angle or a 5 common on the speed square rafters gauge and on the shallow end as far as steepness) and a 12/12 (which is a 45* angle and at the sharp end for steepness.

    There are lots of things to consider when choosing a pitch for your roof. Generally, the steeper the roof, the less the weight pushes straight downward. As in a 12/12 roof transfers most of the load to the walls, mostly downward towards the foundation.

    The exact opposite happens with a more shallow roof. A 5/12 for example will need to hold more weight its self (like a floor would) and whatever percentage of stresses that are transferred to the walls are more pushing outward on the walls than downward on them.

    We have all seen the roofs with a big droop in them right? Highest at the two ends and lowest in the center? This is most likely due to the walls being pushed outward over the years. As the bottoms move away from center, the top looses elevation. Collar ties, collar ties, collar ties. Proper collar tie installation, and roof design prevent this from happening.

    The weight referred to above would be the weight of the roof it's self including everything rafters, collar ties, decking, felt paper, ice& water barrier, shingles, and nails which easily passes into the thousands of pounds on houses and garage size roof systems, also add any snow & ice to the equation and anyone can imagine the tremendous forces.

    That's not to say one is better than the other, they both have pro's and con's. Just that there is lots to consider depending on what you are building, how wide it is, and what kind of weather you (or more so the roof) will be facing.

    Hope that helps ya.

    Also, when attaching the rafters, where on them do you nail? It seems obvious that you'd insert through the narrow part of the 1 1/2" side into the peak board, but surely more than 1 nail would be required. My framing nailer holds nails up to 3" long. Would I need to buy a gun with longer nails or do I toe-nail from the side or neither of those? ;) thank you for your help!!

    Joe, great instructible! Is it necessary to make two cuts on the ridge beam side of the rafter to remove 1/2 the width of the beam or could you factor that reduction into The original length? Also, do you have a blog on measuring and installing the ridge beam these rafters will tie into? I'm finishing a play house for the kids with a 5/12 roof to match my house!

    1 reply

    Thanks for your comment Jlgulley3.

    No you could subtract the full with of the ridge from your buildings overall width, and then continue with the formula, but for ease of explanation in this forum I just chose to show "the cutting it off after" method.

    Unfortunately I have no blog yet, but the thought has crossed my mind, and I just may start one someday... Thanks.

    The measurement of your ridge will be the same as your building length from gable end to gable end. Installation depends on the size, but this generally works for things like sheds and play-houses....

    Install 3-4 sets of your rafters and let them lean against each-other at the top with an angle brace or two on each side so they wont just flop over. Lay out all of the rafter marks on the ridge (2' O.C. is 23&1/4" to the first one and then every 24" from that first one. 16" O.C. is 15&1/4 and then every 16" from the first.) then push it up from below between the rafters, when you let off on the ridge, the rafters SHOULD bind on it and stop it from falling back down through. Best to have 3 people just to make it a very east task, fewer than that, and it can try your patience.

    Hope that has helped, any other questions.. don't be a stranger! Stop in and ask!

    Post some pics of the play house when your done?

    Thanks for your question,

    For people who don't want to shell out $50.00 - $100.00 on the calculator, the brain works for free. Scroll down and view the comment from "wills1" and my reply to him for a more comprehensive answer.

    P.S. Why memorize a booklet full of directions for a calculator when all you have to do is some basic math??

    could you do it without being a even number like your run is 10 feet 3 and 7/16

    showing how to convert it

    1 reply

    I have added this scenario to Step One of the Instructable. Thank you for your feedback and this excellent suggestion.

    Happy framing!