I’m into the mathematics of roof framing!
I was thinking the other day about the 2x sleeper board that the valley rafters rest on when doing a fill onto a sheeted perpendicular roof.
Typically I snap out the valleys on the roof sheeting and set the ridge board. I run a string line or straight edge perpendicular to the ridge plaining into the valley then butt a 2x running parallel to the valley into the straight edge which gives me the setback from the valley line to the square edge of the 2x.
If I were to cut a bevel on the 2x to match the plain of the roof I would slide the block onto the valley line and scribe the straight edge onto the end of the 2x give me the bevel cut.
The question!
How do you figure mathematically the angle of the bevel on a 2x sleeper?
It’s not the same as the bevel cut, if you were to backout the top of a valley rafter because the 2x sleeper is laying at a different angle than a vetical valley rafter.
Any thoughts?
Howie
Replies
Howie,
Try this link.This question has already been worked out by many much smarter than I.
Jon Blakemore
RappahannockINC.com Fredericksburg, VA
Enter the pitches and plan angle in this Hip/Valley Sections Calculator, click, and you have your bevel angle.
The formula is:
Sleeper Bevel = 90° – (Sum of Backing Angles)
There's an illustration further down the page of the angles at the Valley trough showing why the formula works.Joe Bartok
Yes it's just a math question!
I normally wouldn't make that cut.
I just like figuring this stuff out.
Thanks for the Replys!
Howie
Oh man I forgot that video I posted. that's crackin me up.
Well, I am a retired framer and now a custom builder. If I understand, I am impressed that you would consider making this cut, but I wonder why?
We always backed the 2x out of the valley far enough that the top outside square edge is in plane and fastened it. This results in plenty of nail backing for both the valley rafters and decking. It worked for years.
For me, when I had that question originally it was purely academic. I have a feeling the poster is the same way. Once you start learning the math for roof framing, it becomes an addiction.
howhighlites: The Mathematics of Log/Timber Roof Framing and Joinery ... browse and enjoy!
Also try Joseph Fusco's Tutorial And more goodies from the Timber Framer's Guild
Addicted??? Did someone say addicted? Who's addicted?Joe Bartok
Joe,
Thanks for the links your helping my addiction!
Howie
I still have all the hair I had when I got into all this math ... at least I think I do ... There are some books published around the turn of the century which may be downloaded at Steel-Link. Not strictly stick framing but the math is still the same.
Joe Bartok
Edited 2/25/2006 3:31 pm ET by JoeBartok
Joe,
Have you read "Roof Framing" by Marshall Gross?
It's a permanent fixture in my truck.
Much easier to understand how to calculate roofs I feel than
the link you gave me for Joesph Fusco.
I like the timber framing sites though, Thanks!
Howie
You should check out Will Holladay's book "A Roof Cutter's Secrets". It is much easier to understand than Marshall Gross book. I think you'd like it. It's got a lot of really great roof framing pictures.
i too am a huge fan of will's book, the roofcutters secrets.
he seems to have come up with his own system of figuring, slightly different than some of the others, he also has an appendix for use with the construction master calc, but most of all i have always used similar systems of my own design, modifying what i learned from others, and will's is very complimentary to what i came up with myself.
also will and i have a geographical background in common, i was raised and started my apprenticeship in santa barbara county in 1976. according to the book that is where will did most of his work, i recognize the style of construction in the central california coastal mansions.
i would just like to re-write the chapter on rake walls for will, comprised from my own notes. in mid 80's i worked a job in fremont ca. (east bay area) where in a tract setting all the standard height square walls were framed offsite and trucked in. for six months i did nothing but frame rake walls on 4 different plans. i worked all by myself away from all the activity on this site, didn't even raise the walls i built, that was done by crew offloading trucks.
to keep from going insane from boredom i started experimenting with different techniques of framing and timing myself while trying to keep a steady pace to see which way was most effecient. i came up with a couple of shortcuts and what i think is a simpler way than in wills book.
"to keep from going insane from boredom i started experimenting with different techniques of framing and timing myself while trying to keep a steady pace to see which way was most effecient. i came up with a couple of shortcuts and what i think is a simpler way than in wills book."
From:
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I'm not sure if it's the cold weather keeping everybody inside this time of year, but thsi forum has been absolutely booming when it comes to questions, advice, and project photos. The sad thing is that some of the editors have been looking at these projects and reading these tips, and thinking "that would have made a great article!"
So, I wanted to post a message here and extend a personal offer to anybody out there who thinks they might have a technique, concept, or project that would fit our magazine content, and would help entertain and educate our readers.
I know that dozens of you have the experience, and many of our regular authors were discovered right here on BT. For instance, Cliff Popejoy went from giving electrical tips here on BT to being our go-to guy when it comes to electrical articles.
Now it's your turn. If you are interested, check out our author guidelines, and post a message here describing some of your upcoming projects. I will be checking back to get the discussion going. We would love to hear from you, and would love to get some authors for the magazine.
http://www.taunton.com/finehomebuilding/pages/fh_authorguide.asp
Justin Fink - FHB Editorial
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View ImageReply"he...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
There may or may not be a rake wall article in the future in JLC. We may do one. The next house we frame, end of next week, will have some rake walls. Here's the last pic I have of one we did a year and a half ago
http://pic9.picturetrail.com/VOL293/2163851/4215098/76883512.jpg
tim i think you and i have had this discussion before, i have moved to the east coast and i also have a new computer and internet service provider so it was easier to sign on with a new screen name but before i was signed in as skids. both of my screen names are nicknames, the new one is from some co-workers here in north carolina, when i hired on as a framer for a general contractor his hispanic help referred to me as primero and i had to explain i was not number one, maybe number two?
as per framing of rake walls i was trying to find a previous post where i describe the technique but couldn't find it and gave up. it looks like you are doing what i would do by snapping lines and framing walls by nailing only bottom plate and snapping and cutting tops of studs after bottom is nailed and on the line. i would also place but not nail fire blocks to help hold studs on layout, i also use the occaisonal 8 penny toenail to hold stubborn studs, but i think the key is in being able to cut the studs by backcutting the ones that face the opposite direction from your saw foot.
the big idea is just to reduce it as much as possible. if you don't build rakes very often, or frame a lot, you should probably not try to back cut angles on top of rake studs.
Howie, I didn’t get into all this framing math until seven years after I terminated my employment as a log fitter (well, I thought I terminated my employment, but …). A friend was having trouble figuring some angles and asked me if there was a formula for the angle between two planes. So I did what you are now doing and many others have done: I worked out my own solutions. I’m still a newbie in terms of the Internet but I think forums like this are great! It’s good to meet others who have an interest in working with applied math, kick ideas around and work the bugs out of them.
Here’s some more ‘Information Overload” for you. A link to more of my online Math Notes, material I generally post as links in forum discussions. The slideshows and calculators work best if viewed with an MSIE browser.Joe Bartok
Thanks Joe!
I've been interested in Timber framing for years and the math, all though I haven't had the opportunity to build true timber frame trusses or structures.
We build a lot of high end homes and I'm currently building four decorative 8x10 scissor trusses that span 24'. We have all the lap notches and miter joints, just not the mortise and tennon notches of true timber frame. We're using 3/4" rods with decorative washers spec'd by the architect.
Thanks for the Math notes link I'll check it out.
Howie
Hey drop me an email. I would love to hear some of your tips. I think we've got a good system going, but it evolves everytime we do it.
Dido on sharing the wealth!
I would like to think that I've frame rake walls every way a board and nail can go together, but I doubt it.
Would love to here your techniques!
Howie
to keep from going insane from boredom i started experimenting with different techniques of framing and timing myself while trying to keep a steady pace to see which way was most effecient
A man after my heart!
Don't just talk about those notes Segundo....start a thread!
blue
Thanks!
I'll check it out !
I use a scientific calculator I like knowing the numbers that I punch in. I can tell when the numbers aren't adding up, just something I'm used to.
I haven't used a Construction Master, but seems to me that you just need to now your pitches and it does the work for you. I like to know the reasons why I get the anwser I get.
I wouldn't mind playing around with one though, see how it works.
Howie
OK, I understand enough to where I am going to backout. I do not need any more addictions. Breaktime already causes me to lose too much valuable time.