Beginner’s Guide to Roof Framing - Cutting a Rafter, Step-by-Step
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- čas přidán 19. 06. 2024
- How to guide clearly explains: The terminology and components of roof framing, Step-by-step instructions for laying out common rafters, Three quick methods for figuring rafter lengths.
Buy Roof Framer's Bible: www.roofbible.com
0:00 Intro
0:58 What is a gable?
1:43 What is a common rafter?
2:34 Run and rise
5:07 Intro to framing square
7:20 Rafter lengths - 3 methods
11:42 Step-off method
13:35 Rafter table on framing square
14:30 Roof Framer’s Bible
16:17 Laying out a common rafter
18:59 Easily frame any roof
Author’s Bio:
Barry Mussell started framing houses over forty years ago. He built over 300 homes and commercial buildings with his own hands, before taking on the role of Framing Manager for a large home builder. He trained and supervised hundreds of framing crews who built more than 18,000 homes across the southeastern United States. Thirty years ago he wrote Roof Framer’s Bible - The Complete Pocket Reference to Roof Framing. It has been sold all over the world. He is now focused on training the next generation of carpenters and tradesmen.
Thanks for watching! Be sure to check out our playlist for all of our videos.
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How can I obtain your roof framing Bible thank you so much
You can go to roofbible.com, or you can order directly from Amazon. Thanks for watching. Have a great day!
Wow, great simple and visual. Makes it easy to follow the terms and steps.
Finally a video with excellent detail!!! Thank you
Glad it was helpful!
An extremely clear and concise video demonstrating the fundamental layout and cuts to produce a gable roof frame.The explanations of various roofing terms ( and components) combined with diagrams was most helpful, particularly for those of us living in countries outside of America ( UK in my case). I will certainly be viewing your more advanced videos on roof framing. Many thanks for providing such informative content (for us beginners)!
Thanks for watching!
Thank you so much, can you please keep adding more videos I bought the roof framers bable and I learn a lot with your 20 min video today
this video is one of the best on youtube educating people about roof slopes and all of its aspect. I got my associates from a junior college in home building and they don't even teach this in class. This is hands down the best ... thks
Thanks for watching!
You really made this easy to understand. Thanks.
Glad to be helpful. Thanks for watching!
You have a lovely assistant.
Thank you. You are the first person to explain this to me, so I can understand it.
Glad you enjoyed it. Thanks for watching!
One of the best instructional videos I have seen, nice work!
Thanks for watching!
Great video!!! Thanks for posting! Everything made complete sense. 👍
Great! Thanks for watching!
I'm gonna be doing my shed this summer, so your video will be highly helpful.
Thank you
Good deal. Thanks for watching!
Thank you for making it very clear. Much appreciated.
Good deal! Thanks for watching!
Very helpful and easy to follow. Thank you. I think it's time to tackle a project. 😊
Thanks for watching!
Awesome video Barry... thanks for sharing! Keep these coming.
More to come!
I’m a new subscriber. I actually love the way you teach, you guys broke down every step, lol I’d catch myself trying to figure out why you left steps out, only to find out I was the one trying to push the carrot in the mules backside, trying to get him to push the cart! Thanks for a great video
Great to hear from you. Thanks for watching!
Thank you. I found this instruction very helpful.
I'm glad you liked it. Thanks for watching!
Thank you for writing that framing rafter bible. I should get a signed copy before they are all gone.
Thanks for watching!
Brilliant video and explanation!
Excellent tutorial video. Thanks.
Glad you liked it. Thanks for watching!
While I'd heard these terms many times, I hated that I didn't know exactly what each actually meant. Thanks for breaking it down for us newbs!
You're welcome. Thanks for watching!
You explained this so well, thank you!
You're welcome, and thanks for watching!
Well, I wasn't looking for you today, but I have been looking for you for a long time. Subscribed!! And I'll be back. Thank you. 😊
I like your "handle". I'm glad you enjoyed the videos. Thanks for watching!
Definitely the best video I’ve seen on the subject.
Great! Thanks for watching!
This is great, thanks for sharing! Greetings from Norway! God bless! 🇳🇴☦️👍🏻
Thanks for watching!
Great video!
Awesome instructions.
Glad it was helpful. Thanks for watching!
Thanks! Looking forward to a video on shed roofs!
Thanks for watching!
that was really helpful, thankyou
Glad it was helpful! Thanks for watching!
very well explained thank you
Thanks for watching!
Nice presentation. I like to think about Pythagorean theorem so found this all of great interest and helpful.
Glad you enjoyed it!
Damn useful information. Great explanation. I'm a B General Remodel Contractor in Nor Cal & learned much here - I'll go grab your roofBible. Thanks Oh, and Anna is pretty handy to have around... ;)
Thanks for watching!
Excellent work
Thanks for watching!
"The term “birdsmouth” in the context of roof framing refers to a specific type of joint or cut made in a rafter. This joint resembles a bird’s mouth, hence the name1.
In light frame construction, a birdsmouth joint, also known as a bird’s beak cut, is generally used to connect a roof rafter to the top plate of a supporting wall. It is an indentation cut into the rafter, consisting of a “seat cut” (the face of which rests on the top plate) and a “heel cut” or “plumb cut” (the face of which lies parallel to the supporting wall), forming a shape resembling a bird’s mouth2.
The indentation should not extend unsupported on the interior in order to maintain the structural integrity of the rafter because the unsupported section can split along the grain of the wood2. The joint is generally fastened with nails by toenailing the rafter from the side into the top plate below2. As a general rule, no more than one third of the depth of the rafter should be removed, in order to maintain structural integrity."
Well said. Thanks for watching!
what a great video, thank you so much
Glad you enjoyed it. Thanks for watching!
Great video.
I’m looking for a roof video that does not use a ridge board or birds mouth as part of the roof structure but sandwiches the rafters at the ridge, uses metal anchor things where the birds mouth would be and uses a roof joists.
learned a lot... Thank you!
Glad to hear it! Thanks for watching!
Very simple explanation 👍👍👍 love it,,
Thanks for watching!
Hey best tutorial on rafter building
Keeping it simple
Just subscribed
Thanks for watching!
Great job guys
Thanks for watching!
thanks alot for the information.
Most welcome! Thanks for watching!
Thank for Sharing
Thanks for watching!
I will be buying your book sir! You and your assistant are excellent instructors!
My book is Gun Sense.
Thank you sir. I'll have to check out your book. Thanks for watching!
Gun Sense eh? Nice
Question: In your book, did you say anything about what 2A wording really means?
Examples
Well Regulated: Means to be ready, in working order.
Militia: Any man ages 18 to 45. ( since then, it has grown to include women, and nearly any age, mostly 18 to end. Court cases has allowed underage to defend homes also.)
Hello, I like your videos explanations,looks easy. Thank you
Glad you like them!
Great job
Thanks for watching!
Thank you!!
You're welcome. Thanks for watching!
this is the exact thing size and everything lol i was looking for
Thanks for watching!
Very skilled brader ❤
Very well explained, congrats. Just a minor adding to your explanation, as it's intended for beginners, is that a nominal 2x4 is actually 3.5 inches wide ( when explaining the birdsmouth); other than that, very good.
Thanks for the feedback.
Very helpful for a DIY homeowner like me. Do you have a video on erecting the roof ..attaching the rafters to the ridge and walls?
No, not yet. Check out Larry Haun's video at Fine Homebuilding. It should show what you need. Thanks for watching!
I was having trouble sleeping. Thanks 😂
Thanks for watching!
Thank you
Thanks for watching!
Clear as mud.
Thanks for watching!
I have always wondered how they make the Cuts on the Roof Rafters. I can build the Walls, just not the Roof. Thanks for making this Video. I will definitely order the Roofing Bible. Subscribed and looking forward to seeing all your Videos.😁👍👍
Great! Thanks for watching.
I have cut many roofs You have to cut a few to really learn how to do it. What is amazing the chinese cut very complicated roos a few thousand years ago
Just lay your rafters on the floor before the walls go up and make your template for the rest. It gives you the proper width and go from there.
Yep, you can do that! Simple roofs are not hard. Thanks for watching!
There you go !👍🏼
I am a beginner so thanks for the video. By the way do you have any video on replacing a rotted roof plate, rafter and joist on a concrete sill? Continue making videos for us beginners.
No, sorry. Thanks for watching!
Thanks
Thanks for watching!
I think you guys need Holmes on homes. At the end, Holmes gets a big hug from Anna.
I've noticed in the comments a lot of whiners and complainers about this presentation. Problem i see today is too many short cuts to building and therefore creates too many problems due to electronic devices to "simplify" the math. I've been building residential homes for 30+ yrs, wish i had this book when i first started out. Excellent presentation 👏 👍
It's great to hear the feedback. Yep, it is difficult to please everybody. I appreciate the compliment. Thanks for watching!
I just came across your site, these videos are excellent. Can i ask a question about your rafter square? Is it a standard carpenter's square or is it a particular brand that has that table printed on it? Thank you
Historically all the large framing squares (24" x 16") had rafter charts stamped on them. Some of the cheap consumer level squares sold now don't include the tables. The professional squares of many brands will all have it. Thanks for watching!
excelente escuela
Gracias por ver.
How to know the height of the hip onto which the common rafters sit from the wall below.
how long can the span be with out putting a post in the middle?
It wasn't covered in the video, but you always must have either a ceiling joist tying the rafters together at the plate line or a structural ridge. It the bottom ends of the rafters can't push out, the ridge can't sag. Or, if the ridge is structural and can't sag, then the rafters will not push out or spread at the bottom. Obviously there are limits to the spans of both the rafters and the ridge. The allowable span of the rafters will vary depending on the material / size of the rafters. If you are using a structural ridge, it has to be designed to carry the imposed loads. I wish the answer was simple, but it depends on a lot of different variables. Thanks for watching!
Nice
Thanks for watching!
I'm sorry, did you say something? I was too busy staring at Anna!! hahaha....Great Video!
Thanks for watching!
I'm getting ready to build an off-grid cabin in an area that has no building codes. I'm trying to find info on ridge board or ridge beam sizing based on span and load. Does your roof bible have that info in it? I've built many houses but always used trusses, this is my first time with rafters.
No, Roof Framer's Bible doesn't address any structural beam sizing. There are just too many variables. If you have ceiling joists attached to the rafters on each side you only need a ridge board. The ridge board should be one size larger than the rafters, so if you have 2x6 rafters you will need a 2x8 ridge. If you have a vaulted ceiling (no ceiling joist tie) you will need a ridge beam large enough to carry the load of half the span. There are some beam calculators out there. Just figure out the loads for your situation (dead load, live load, snow loads, etc.) and plug those loads per square foot into the calculator to get a beam size for your ridge. This isn't really recommended for DIY unless you have some experience. It is best to contact a competent person or engineer. Good luck. Thanks for watching!
Thank you for your video, but i have a question. It is not necessary to have a rafter tie or a collar tie?
Yes, you are correct. Although beyond the scope of this basic video, it is necessary to have either a tie across the building or have the ridge fully supported. If the ridge can't come down, the rafters can't push out. A ceiling joist tie across the building will also resist the rafter thrust. Thanks for watching!
thanks for the awesome video... however, help me understand something... when using this primary method of measuring the rafter in this video, doesn't it require the rafter to already be in place as shown? I can follow the Roof Bible and the 'alternative' run method, and I can follow the method that was used, but it just seems like the rafter would have to be in place... The step off method also seems like the rafter would also have to be in place...
Another question, the rafter tail is arbitrary, correct? If I want it to be 12", fine, or if I wanted it to be 18", that's fine as well, correct?
Thanks again...
I placed the rafter into position to aid the viewer in understanding its final placement. None of the methods of determining the rafter length require it to be so. In practice these are always laid out with the boards on the saw horses. As to the overhangs, you are correct. The length of the overhang can be whatever you desire. Regardless of length they are laid out with the same method. I trust this answers your question. Thanks for watching!
I have been cutting rafters since 1968. Here is a simple way. First you need to get a book that that tells you the rafter length by the span of the rafter.. In this plan the span is 8' so you look under common raffter by span go down to 8 ' It would automaticall tell you the rafter lngth of one rafter.( the run of this rafter woulld be 4' but you look under 8'span. Now the ridge ia 1 1/2'' wide so before looking up the apan you deduct 1 1/2'' from 8' so you would actually look up 7' 10 1/2'' The best part of this book If you have a hip or valley( they are both exactally the same length) you would take the same measurement o the span off the common 7' 10 1/2'' and look under hip or valley it would tell you the exact length of one hip no shorting needed
Hi, as per your recommendation iv purchased both your book " Roof framers bible" and the "A roof cutters secrets " as they go hand in hand. I got your book first and love it. I only recently got the secrets book and noticed some discrepancies between the two.
For example in your book 10/12 page 52 the rafter ratio is 1.302 which I believe is right. But in the secrets book page 299 on same 10/12 pitch rafter it has a ratio of 0.8333.
I must be reading it wrong. Could you have a look please?
Thank you
Also I noticed that the tables in your book stop at 25 feet, what if the span is greater then that
It is just a confusion of terms. On page 298 of Roof Cutter's Secrets in the chart for "Rafter line-length ratios" you will see 1.3017, which the the same as the rounded number in my book for the rafter length. If you look on page 299, the "Roof-Rise Ratios" gives .8333. This is giving the rise of the roof, not the rafter length. If you look back at Roof Framer's Bible page 52, directly below the 1.302 factor for rafter length, you see the factor .833 for rise. So, it is the same in both books. Just a little confusion as to how to read the charts. Thanks for watching!
@@RoofFramersBiblehi, thank you so much h for getting back to me so quickly. I see it now ha. If it had teeth I'd of got bitten. I love your book. I don't get all of it yet but most of it makes perfect sense
Anna, where were you at the end with the eave cuts? “Hey wait why measure 4” for the plumb cut of a 1x6 facia board?”
I have generally used 4" for the plumb cut when using a 1x6 fascia. This allows the finish fascia to extend up to the top of the roof sheathing and also to hang down with a roughly 3/4" reveal from the bottom of a 3/8" soffit material to the bottom of the finish fascia. I hope that answers your question. Thanks for watching!
This is supposed to make it clear for the beginner!! lol 😅😊. How about making all rafters the same size once you got the 1st 2 done?
Yes, you're right. We would normally cut one pattern and use it to cut the rest. I just thought it important to get some rafters up to look at. The hope was to provide perspective to help them understand the explanation. Thanks for watching!
I was a grunt on a small production crew with 2 old boys in the early 80’s. Their method of explaining rafters was similar to yours save for the blocks wizzing by my head, followed by choice words and screaming to “hurry the #%* up.” Good times. Learned a ton from them and even to this day I venture out to their gravesites to pay my respects and spit on their headstones.
Ha! I love that. We can laugh, but it's true that you don't really understand framing until you have lived what you describe. It never was and never will be an easy job. Thanks for watching.
Nice video, the biggest takeaway for an inexperienced person that translates to any segment of construction. Its a process. Research, plan, follow each step, dont cut corners, be patient. Ask for help when you need it and sub out anything required by law. Follow all codes and get it inspected. This I cant emphasize enough.
True, so true. Anybody can do anything if they slow down long enough to understand it and approach it with humility, and a recognition of their limitations. Thanks for watching!
Good info.
My question is on a L shaped building what would you call that roof? The corner is what im interested in.
edit Hip is the keyword i wanted i believe
You are correct. The corner of two gables on an L shaped structure would be a hipped corner. Thanks for watching!
Is it possible to have a birds mouth on the interior of the top plates and plumb cut flush with the exterior walls?
You can certainly cut the rafter tail off flush with the outside of the exterior wall. The birdsmouth would be the same, sitting on top of the plate.
How do you get your HAP if your rafter isn’t already up though?
H.A.P. is the abbreviation for "height above plate". It is measured vertical right above the outside of the plate. It is determined by the depth of the notch for the birdsmouth. You may want to watch our first video "Beginners guide to roof framing" to understand H.A.P. and positioning of the birdsmouth. Thanks for watching!
how did you determine the height of the ridge beam? and/or how did you determine where the bird mouth went?
Many times you don't need to determine the ridge height. You simply calculate and set the rafters and they will set the ridge height. Of course you can easily calculate the ridge height as needed using the rise and run. The height of the ridge above the plate would be the total rise of the rafter plus the H.A.P. dimension. Thanks for watching!
You don't need to know that normally, unless the rise is critical, determining the pitch
What you need to do is haphazardly mix use of metric and imperial measurements like we do in UK to get spectacular roofing outcomes.
Ha! I bet that would be fun. I have sold books in metric countries for years. I always wondered exactly how they were using them. I guess you guys have a thousand years worth of housing stock that was built with imperial measurements. I'm sure that can make life interesting. Thanks for watching!
So rise is determined by ? Roofing materials has to be some or just preference on looks
Rise is determined by the roof pitch that is selected. Most of the time the pitch is determined by architectural preference. Often an architect will specify a steeper roof so that they can achieve a larger roof mass. It is just a matter of balancing the proportions of the house. It is one of those "beauty is in the eye of the beholder" situations. Personal preference and architectural style will dictate the roof pitch selected. Thanks for watching!
I'm an inexperienced builder who's looking to build a small house (~600-800 sq. feet) and do as much of the work myself as possible, including framing. Do you think a shed roof would be easier for me to build correctly, versus a gable style roof?
Neither roof is difficult, so that shouldn't be the tail wagging the dog. The architecture should dictate the choice. Generally that would be a gable roof. It largely depends on the style you are trying to achieve. Good luck, it is a great feeling to build your first house.
@@RoofFramersBible Thanks much!
Do you have a video on how to build a shed roof?
No, I don't have one specifically on a shed roof. However a shed roof is just one half of a gable. The same principles apply. Thanks for watching!
Hello, I have questions if I my. I have a shed roof, on the lower side like to put new house. Which kind of style you think is good for, this shed roof is a barn, I need one room and living room. Simple one. Thank you very much
I don't have the larger context of what you have. It would be difficult to say without it. The best path is to keep it as simple as possible. Draw a scale drawing and try different configurations to find what works best for you. Thanks for watching.
@@RoofFramersBible thank you. Good idea
Thank You Roof Jesus
Thanks for watching!
Thanks ❤❤ it😊😊
Thanks for watching!
What happens if the seat cut is only 2" horizontal? Wouldn't it change the overall height at the peak off the structure? I think this is where I messed up trying to cut my roof, thinking the height off the structure at the peak is fixed
Generally you make the horizontal cut of the birdsmouth the width of the wall, however a 2" seat cut is fine in most cases. The limited load on those rafters is fine with a smaller bearing surface. The slope and length of the rafter is figured from the top of the rafter, so that remains the same regardless of the H.A.P. (height above plate). So if you have a smaller seat cut that will generally result in a taller H.A.P. and that would raise the whole rafter up including the ridge. This isn't a problem unless it is tying into another roof where the height is fixed. I hope that answers your question. Thanks for watching.
Hi this book available in metric
Is it available through other online book seller sites?
All of our order fulfillment is through Amazon. I believe you can order it from other sites, but of course it would be a longer delivery and they would also source it through Amazon.
It is not opening for me either! I hope you get this fixed, I’d like to purchase a few copies. Got IT support?
That is strange. I have tried the links and they seem to be working. Your can go directly to Amazon to order it. The link provided goes to our website but Amazon handles all our order fulfillment anyway, so if it won't work just go to Amazon and search "Roof Framer's Bible". Thanks for watching.
@@RoofFramersBible thanks for the reply and the quality video. I know this stuff but using it to teach a young man that needs to learn. Looking forward to more videos. Added subscription
If I want to learn more and better it's up to me to marry the assistant 😂
😂😂😂😂😂
Sir,please tell me rafting fomula standard
12feet breath
24 long houses
To figure the rafter lengths you would first need to know the roof pitch. The steeper the roof the longer the rafters. Thanks for watching!
When I multiply 4ft by 14.42 I get 57.68 which is closer to 57 11/16. Are you rounding up to the nearest 1/8th? Or am I doing something wrong? Is this a minute detail?
Yes, I generally round to the nearest 1/8". That is typical for rough framing. The irregularity of the framing lumber will affect it more than the rounding. Thanks for watching!
@@RoofFramersBible awesome video thanks for making it! I’m a complete beginner and I think I’m about to build a roof!
Good video but you completely skipped over how to connect the common rafters to the ridge. Was the ridge just nailed flush into the end of the first rafter? If so, then how is the facing rafter nailed to the ridge?
Yes, the ridge is face nailed to the top end of the first rafter. The opposing rafter can be "toe-nailed" into the ridge. You typically would also face nail into the rafter from the opposite side of the ridge. You simply start the nail up next to the side of the first rafter and angle the nails to engage the center of the opposite rafter. I hope that answers your question. Thanks for watching!
I see an error of the explanation. You stated that you wanted four inches gor a full bearing seat cut, but the framing point was ghe outside of the wall frame. You need a four foot run plus the thickness of the sheathing minus on half the ridge gor your calculations which actually translates to a 4-0 snd and 1/2 inch run. Then that four inch bearing surface works.
I like you taught my students every possible way to calculate rafters to my students including snapping a bisecting line on the floor of the shed, setting a block representing the ridge snd and using the side and end walls as a marker to establish how the birds mouth fits using a sevond block representing the top plate.Your presentation was pretty much flawless,but I thought you would not mind if I pointed this out.
I usually use a calculator to establish to the sixteenth of an invh accuracy, but feel that your rafter book would do it faster snd more reliably and without batteries and the exoense of a calculator.
Good work,sir
Thank you for the response. I suppose I didn't explain it fully, but the span of 8' was to the outside of the sheathing on each side. The model didn't have any wall framing. It was just a top plate screwed on the edge of the sheet of OSB, so I used the full sheet for the span. Thanks for watching!
If you use a rafter book it is calculated by the span , so you would look up 7' 10 1/2 '' and you would get the exact length of the rafter. say if it was a hip you would look under hip or valley and use 7' 10 1/2'' and that would be the exact length of the hip or valley no shortening
You are correct. Most of the old rafter books used the overall span in the tables. I used the "Full Length Roof Framer" book for many years. Thanks for watching!
@@RoofFramersBible Using the total span is better . Say you are cutting an L shaped bilding you take 2 measurements and cut the whole roof. Say you need to cut a hip between 2 ridges. you could add 1 1/2'' to the span of the common to the lower ridge that would get you to the far side of the ridge then calculate the higer hip using the span method and deduct the difference of the two hips
What I’ve never understood is that no one ever seems to mention how the depth of the birds mouth cut would affect (slightly) the angle of the rafters. Or is this so slight that it is ignored? It would also affect the angle of the plumb cut I would assume…?
Actually the rafter doesn't change pitch because you notch the birdsmouth. The entire rafter drops down due to the notch, but the pitch or slope doesn't change. Also because the pitch doesn't change the plumb cut doesn't change either. Think of the roof like a hat on your head. Notching the birdsmouth allows the "hat" to drop down lower, but it doesn't change the pitch of the roof. Thanks for watching!
33.6°
I was always told that it’s called a bird’s mouth because when cut it looks like a open bird mouth 👍🏻
I suspected that may be it, but I had never heard it said. Thanks! Happy new year and thanks for watching.
Happy new year to all. Look forward too new videos. As I was also told every day is a school day. Regardless of how much you think you know 😊👍🏻
I have been cutting roofs for over 50 years,isn't your book a copy of A.F. Riechers book Full Length Roof Framer.This book was around along time before I got mine in the 70's.
Yep, that book was first published in 1917. My Dad bought one in 1949 and I used his copy when I started framing in 1979. In the 80's we started doing a lot of bastard hip roofs and of course Riecher's book doesn't cover those. In 1993, I was trying to help someone frame a bastard hip and he asked "don't they have a book for that?" I said no, maybe I ought to write one. Driving home that day I decided that was a good idea. Roof Framer's Bible has all the standard pitches like Riecher's and also 68 different combinations of bastard hips. It also has a bunch of other stuff, such as octagon roofs, etc. Thanks for the note, and thanks for watching.
Is the bible available for download?
No, we don't currently offer a digital edition. Thanks for watching!
That would be a great offer. Saves on trees and shipping...@@RoofFramersBible
So your model is 8 feet span ( @ 4.24min) but you run all the calculations (including the figures on the framing square) as if the span was 12 feet (with rise = 8 feet)? Then a@ 9:42 the drawing shows 8 feet for span (4 feet for run) albeit the span on the diagram showing on the top left corner shows a span of 12 feet? Your presentation is excellent bar these aspects that personally have left me unsure as well as the method to calculate the rafter length on the framing square which could be more clear but maybe you have a presentation just for this on another video (?). Anyway, thank you!
The model in the video has a span of 8' and all the rafter lengths are figured from a run of 4'. At the 9:42 point in the video, which you reference, what you see in the upper left corner is not indicating a run of 12', but rather is the standard way that roof pitches are called out on plans. Any plan that you see will indicate a 8/12 pitch in this fashion or format. I hope that answers your question. Thanks for watching!
@@RoofFramersBible Thank you for taking the time to answer which is very much appreciated. My second question: my bad and you are right in pointing out 8/12 as the pitch proportions regardless the length of run / span - I am embarrassed because I should know this better and somehow I raised this question. My apologies. Re my first question the same is answered by the second one: an 8 feet span model where the calculations were run proportional to 8/12 (a rise of 8 feet for a 12 feet span) being the rafters' length calculated based on a 4 feet run. I hope Pythagoras has not read my questions!
1463.6 mm is rafter length along birds mouth line. I always use trig for calculating
8 inches of rise to every 12 inches of run,
How do I get this bible?
Go to www.roofbible.com, or you can go straight to Amazon to purchase. Just search for "Roof Framer's Bible". Thanks for watching!