Thanks for your clear explanation. I needed to find this out for my DIY project. One does not have to attend carpenter's school for some years to be able to enjoy building something. Even non carpenters like to build. We do not know all the details so we need help. You were open minded and unselfish in sharing knowledge and special thanks to you for this. The world needs more people like you.
Listen, this explanation is perfect. What people aren't considering is that this is the theoretical line length. There are adjustments to be made to the stock. If you want the whole explanation take the 4 year course and spend the 8000 hrs in the trade and be a carpenter. Other wise sit back, relax and say thank you. Or hire a ticketed tradesmen. This is why trade time is expensive, because it's not as easy as watching a 9 min video. Thanks for the video.
I believe he gave a good explanation of it except for the deduction for ridge thickness. I always subtract the ridge thickness from the span and then divide by two to get my run, 👍💪🔨🇮🇪
the run of 14ft should also be converted to inches so the half inch extra of the sheathing can also be accounted for when calculating the line length of the rafter ...so 14x 12= 168....then add .5 ...so 168.5x 14.42= 202.48in.........=202and 7/16
I look at the numbers and I get overwhelmed. I take a few seconds to see what .88 x 16 = 14.08 means and I realize 14/16s it's 7/8s. Then I think to myself: "was that it?!" I'm drowning in a glass of water
Sir, when determining the length of the rafter do we have to add the thickness of the exterior siding? If I plan on adding a half inch thick siding, should I add that to my figures?
Yes, his example assumes this since he said outside to outside. It's always overall external dimensions including finishes. What he didn't point out is deducting half the ridge thickness, but his diagram didn't include a ridge board.
just the hypotenuse of a right angle triangle... the length of the 'rafter' is the square root of the sum of the squares of the other two sides. so if it's 2 feet wide and 1 ft high, it's 2x2+ 1x1 = 5... the square of 5 is 2.236...
12 is the width and the 8 is the rise (UP) so for every 12 inches it rises 8 inches. The math is to figure the rafters length and to help where the birds-mouth would be and this would fit from the center beam to the wall headers (Top of wall) I hope this helps your question
He didn't allow for 1/2 the ridge board width. That's the first thing I noticed, and I get a wonky number when I do it his way. Even if I subtract the 3/4" it still comes out too long. I did the same rafter layouts on CAD and got a different number. CAD doesn't lie, it's accurate to 8 decimal places.
@@Scott.Farkus fine, but no carpenter needs to work to that degree of precision. Lots of timber framed buildings pre-date CAD. They look fine to me. Tapes and squares require no electricity.
Seems like you are making it overly complicated by using a framing square. It's simple geometry and anyone with a high school education should be able to figure it out. Well, at least back in my day, high schools taught geometry...
slope= rise/run he say span= 28, run=14, slope=8/12, (rise/14run=8/12) we need to now the rise, rise= 14runX8/12= 9.33 rise= 9.33 rafter= √rise²+run² , rafter=√9.33²+14² = 16.82 answer
To determine the pitch of an existing roof, it is possible to determine the pitch using a framing square and a level. Hold the level on the blade of the square and hold the square so the 12" mark on the intersects the roof line and the tongue is pointing down. Then adjust the square and level until the level reads level. Then read where the roof line intersect on the tongue of the square. This is the pitch of your roof.
To determine the pitch of an existing roof, it is possible to determine the pitch using a framing square and a level. Hold the level on the blade of the square and hold the square so the 12" mark on the intersects the roof line and the tongue is pointing down. Then adjust the square and level until the level reads level. Then read where the roof line intersect on the tongue of the square. This is the pitch of your roof.
The overhang is usually just added on to the end of the rafters after the birdsmouth cut as a certain number of feet and inches. It is not really necessary to have it as part of the calculation because it does not affect the length or pitch.
Where is the next video, please? I want to bring the American culture here to Brasil. You're so smart and secure. Thank you for the sharing and dedication!!
Welcome to 2019 where if they can't catch it in 9 minutes, they are lost. This is why I ordered a framing square reference bible, square as well as watch a crap ton of videos and been thinking about asking to work along side a roofing contractor on roofing jobs they have whether they teach me to cut them or simply shut the fuck up and just watch. People today have gotten lazy.
One thing i notice is you are not conidering a top plate at the apex to calculate the run which woul be the run minus half the thickness of the top plate which then gives the correct run. That way you have something to attach the rafters to.
I looked for the overhang video. Can you explain the over hang? I have a 10'X12' deck, I would like the over hang off the roof to cover 2' over all sides.
When your dealing with a decimal and you want to find it on a tape measure in 16ths. You multiply the decimal by 16. This will convert the decimal to a usable 16th number on the tape measure. Here he got 14. So that's 14 (16ths), or reduced is 7/8. Really easy once you do a few times.
the easiest way is to get a little book that is available. You look up the rise and the span of the building and it will give you the angle of the ridge beam cut and length from ridge bean to the seat cut.
Jonathan Blankenship . He is trying to figure out what .88 of an inch would be on his tape measure. So he converts it into how many 1/16" is the closest to .88 the answer would be 14/16". If you count 14/16" on your tape is is the same as 7/8" .
when he calculated the .88 into 16th of an inch he got 14/16... when you divide both 14 and 16 by 2, you get 7/8... same thing. like saying 3/4 is actually 6/8ths
Does not look like it, but this video did for me was explain the framing square. I like that, no one around to explain it. Thankfully I found a old one a few months ago in a thrift store for nothing. New framing squares do not have that info on them.
A lot of buildings these days are not built using a ridge beam. If it is used, half the thickness of the beam is the amount deducted from the final cut measurement of the rafter.
Basic geometry (or trigonometry, depending upon which way you calculate it)... You could calculate the angle taking the arctan of "rise divided by run" (i.e. opposite over adjacent). Then solve for the hypotenuse by way of: cos(θ) = adjacent / hypotenuse hypotenuse = adjacent / cos(θ) rafter = 14 / cos(arctan(rise/run)) rafter = 16.825906 ft Or you could do the following: 8/12 = total rise / total run -> total rise = 8 * total run / 12 -> total rise = 8 * 14 / 12 -> total rise = 9.33333 rafter = sqrt(total run * total run + total rise * total rise) -> rafter = sqrt(14 * 14 + 9.33333 * 9.33333) -> rafter = sqrt(196 + 87.11111) -> rafter = sqrt(283.11111) -> rafter = 16.825906 ft = 16' 13.2145/16" Which way you calculate it depends upon what sort of pocket calculator (or calculator app on your phone) you have...
![How To Make Common Rafters [Measure, Mark & Cut]](/img/n.gif)
Thanks for your clear explanation. I needed to find this out for my DIY project. One does not have to attend carpenter's school for some years to be able to enjoy building something. Even non carpenters like to build. We do not know all the details so we need help. You were open minded and unselfish in sharing knowledge and special thanks to you for this. The world needs more people like you.
Listen, this explanation is perfect. What people aren't considering is that this is the theoretical line length. There are adjustments to be made to the stock. If you want the whole explanation take the 4 year course and spend the 8000 hrs in the trade and be a carpenter. Other wise sit back, relax and say thank you. Or hire a ticketed tradesmen. This is why trade time is expensive, because it's not as easy as watching a 9 min video.
Thanks for the video.
@John Lowell right, some old school carpenters don’t like changing there ways tho
I believe he gave a good explanation of it except for the deduction for ridge thickness. I always subtract the ridge thickness from the span and then divide by two to get my run, 👍💪🔨🇮🇪
@John Lowell Well what are you waiting for? Go get your calculator and come make 6 figures with us. See you out in the field!!
the run of 14ft should also be converted to inches so the half inch extra of the sheathing can also be accounted for when calculating the line length of the rafter ...so 14x 12= 168....then add .5 ...so 168.5x 14.42= 202.48in.........=202and 7/16
I was wondering about that. Thanks for clearing that up
Still thinking of doing part two of the rafter lesson?
I look at the numbers and I get overwhelmed. I take a few seconds to see what .88 x 16 = 14.08 means and I realize 14/16s it's 7/8s. Then I think to myself: "was that it?!" I'm drowning in a glass of water
So much easier with the metric system working out angles, lengths etc
you're going off on a tangent...
@@pinarellolimoncello 🤣
Trick question: what is a one half pitch common rafter. Is it 6 x 12 or 12 x 12?
Just what I was looking for. Thankyou
Great explanation !! Thank You !
Old school carpenter
How is it calculated at how many degrees?
Sir, when determining the length of the rafter do we have to add the thickness of the exterior siding? If I plan on adding a half inch thick siding, should I add that to my figures?
Yes, his example assumes this since he said outside to outside. It's always overall external dimensions including finishes. What he didn't point out is deducting half the ridge thickness, but his diagram didn't include a ridge board.
Is a 10x10 shed good for 3/12?
Its not that complicated is it? Cant you just start with one? and figure it out by looking at it?
Very well explain!
It a very interting i like it hope have more viedios
201.88 inches? From where? ; it must be....20. 18" or 20 1/8" isn't it?
just the hypotenuse of a right angle triangle... the length of the 'rafter' is the square root of the sum of the squares of the other two sides. so if it's 2 feet wide and 1 ft high, it's 2x2+ 1x1 = 5... the square of 5 is 2.236...
Thank you!
Real good explanation
This was done to complicated much easier way
but how do you decide if it is a 6 over 12 or 8 over 12 that confuses me?
Marcichlids !!!!!!!! Revo
Koitom
Marcichlids !!!!!!!!
12 is the width and the 8 is the rise (UP) so for every 12 inches it rises 8 inches. The math is to figure the rafters length and to help where the birds-mouth would be and this would fit from the center beam to the wall headers (Top of wall) I hope this helps your question
He didn't allow for 1/2 the ridge board width. That's the first thing I noticed, and I get a wonky number when I do it his way. Even if I subtract the 3/4" it still comes out too long. I did the same rafter layouts on CAD and got a different number. CAD doesn't lie, it's accurate to 8 decimal places.
@@Scott.Farkus fine, but no carpenter needs to work to that degree of precision. Lots of timber framed buildings pre-date CAD. They look fine to me. Tapes and squares require no electricity.
Seems like you are making it overly complicated by using a framing square. It's simple geometry and anyone with a high school education should be able to figure it out. Well, at least back in my day, high schools taught geometry...
sooooooooooooooo confused
Be nice if the volume of the movie could be louder so I could turn down but couldn't make volume louder
slope= rise/run he say span= 28, run=14, slope=8/12, (rise/14run=8/12) we need to now the rise, rise= 14runX8/12= 9.33
rise= 9.33 rafter= √rise²+run² , rafter=√9.33²+14² = 16.82 answer
What about the thickness of the ridge beam????
Also, he came up with 14.08 but then dropped the .08!!!!!!!
Where did that go?!
.08 of a 1/16th.......if you could even see it you couldn't cut a rafter that accurate.....
@@guitarslinger319 1/16" x 14 would be 1 1/8". Please read charles scott
comment!
@@noblecarpentry you could see that...
how to determine the pitch (6,12) or (4,12) or (5,12) or (3,12) and so, so why is so problematic the overhang thanks
To determine the pitch of an existing roof, it is possible to determine the pitch using a framing square and a level. Hold the level on the blade of the square and hold the square so the 12" mark on the intersects the roof line and the tongue is pointing down. Then adjust the square and level until the level reads level. Then read where the roof line intersect on the tongue of the square. This is the pitch of your roof.
To determine the pitch of an existing roof, it is possible to determine the pitch using a framing square and a level. Hold the level on the blade of the square and hold the square so the 12" mark on the intersects the roof line and the tongue is pointing down. Then adjust the square and level until the level reads level. Then read where the roof line intersect on the tongue of the square. This is the pitch of your roof.
The overhang is usually just added on to the end of the rafters after the birdsmouth cut as a certain number of feet and inches. It is not really necessary to have it as part of the calculation because it does not affect the length or pitch.
To the point and very easy to follow, instead of some complicated equations 👍
I find it helpful he explains those numbers on the framing square. The math is simple. A^2+B^2=Sqrt(C^2). Basic algebra really.
Where is the next video, please?
I want to bring the American culture here to Brasil.
You're so smart and secure.
Thank you for the sharing and dedication!!
Please tell me what culture you are talking about?
4:26 No overhang discussed and won't be in this video. Video then loops.
On a calculator, .42 × 16 = 6.72 round that up to 7, so that's 14 inches and 7/ 16ths for every foot of run
Good grief folks..I'm dumb as shit....and I got it....
Sounds like alot of folks have a problem for every solution.....
Welcome to 2019 where if they can't catch it in 9 minutes, they are lost. This is why I ordered a framing square reference bible, square as well as watch a crap ton of videos and been thinking about asking to work along side a roofing contractor on roofing jobs they have whether they teach me to cut them or simply shut the fuck up and just watch. People today have gotten lazy.
I just use Pythag therom.
Man thank you for the simplified answer.
Did this video play twice or is it just me
I was wondering the same thing
I work in metric, but I would also work imperial
Thank you for doing multiplication the same way I was taught! Very refreshing! Thank you for helping me!
Great demonstration-wish you would have continued down the framing square to show valley and jacks
Awesome. Thanks
One thing i notice is you are not conidering a top plate at the apex to calculate the run which woul be the run minus half the thickness of the top plate which then gives the correct run. That way you have something to attach the rafters to.
Ridge thickness needs to be allowed for, 👍🔨🇮🇪
That was a great explanation. That totally helped me for class. dont see your over hang video.
I looked for the overhang video. Can you explain the over hang? I have a 10'X12' deck, I would like the over hang off the roof to cover 2' over all sides.
Just add 2ft to the rafter length for your total length
@@FirBurger98 correct way 14.42 x 2 = your 2' over hang
Don't you have to take off more then 3/4 if the slope rises above a 4?
5968 not 5768
I have a run of 15 and it will be on a 7 what is my rafter length
Omg 1508
Thank you for this video it's helpful for me
Extraordinary your explanation! Thanks from chile 🇨🇱
Where did the 16 come from; along with your answer?
When your dealing with a decimal and you want to find it on a tape measure in 16ths. You multiply the decimal by 16. This will convert the decimal to a usable 16th number on the tape measure. Here he got 14. So that's 14 (16ths), or reduced is 7/8. Really easy once you do a few times.
it is worng
yeah what happened to the other 7/8 ... his answer looks to be 14/16 but he said . 201 and 7/8 what he do with the other half ...smh confusing
count out 14- 1/16 inch marks on tape rule it is same as 7/8 inch
Racso Zerep 14/16 is the same as 7/8ths. Which is the way it would be communicated.
the easiest way is to get a little book that is available. You look up the rise and the span of the building and it will give you the angle of the ridge beam cut and length from ridge bean to the seat cut.
If you cannot simplify fractions or read and convert them on a tape measure, probably best to get a professional.
master carpinter thks
He don't know
where do you get the 1/16 inches and the 7/8 at the end?
Jonathan Blankenship . He is trying to figure out what .88 of an inch would be on his tape measure. So he converts it into how many 1/16" is the closest to .88 the answer would be 14/16". If you count 14/16" on your tape is is the same as 7/8" .
Jonathan Blankenship 14 1/16 is 7/8 of a inch
Where in the hell did u get the 7/8 from
14/16=0.875
7/8=0.875
when he calculated the .88 into 16th of an inch he got 14/16... when you divide both 14 and 16 by 2, you get 7/8... same thing. like saying 3/4 is actually 6/8ths
also what if the run is 14' 4"
trevor francis in this case, since 4” is 1/3 of 12” you add 1/3 of 14.42, that’s 4.8 so 14.42 times 14 + 4.8
You can’t build the roof then lol
Does your final measurement account for the ridge beam? I think that's what its called..Thanks
Does not look like it, but this video did for me was explain the framing square. I like that, no one around to explain it. Thankfully I found a old one a few months ago in a thrift store for nothing. New framing squares do not have that info on them.
A lot of buildings these days are not built using a ridge beam. If it is used, half the thickness of the beam is the amount deducted from the final cut measurement of the rafter.
How would you figure out the diagonal without the framing square? Pythagorean theorem?
Jarlborg1984 yup
Basic geometry (or trigonometry, depending upon which way you calculate it)... You could calculate the angle taking the arctan of "rise divided by run" (i.e. opposite over adjacent). Then solve for the hypotenuse by way of:
cos(θ) = adjacent / hypotenuse
hypotenuse = adjacent / cos(θ)
rafter = 14 / cos(arctan(rise/run))
rafter = 16.825906 ft
Or you could do the following:
8/12 = total rise / total run
-> total rise = 8 * total run / 12
-> total rise = 8 * 14 / 12
-> total rise = 9.33333
rafter = sqrt(total run * total run + total rise * total rise)
-> rafter = sqrt(14 * 14 + 9.33333 * 9.33333)
-> rafter = sqrt(196 + 87.11111)
-> rafter = sqrt(283.11111)
-> rafter = 16.825906 ft = 16' 13.2145/16"
Which way you calculate it depends upon what sort of pocket calculator (or calculator app on your phone) you have...