Roof Angles

[opie1]

How do I figure the angles for the sheathing going an a corner hip? Most of the time we just snap and cut the ply in place or measure each end and cut it that way. I'm now in the process of making a form for a conc. column base with a sloped top similar to a hipped roof and need to cut the MDO fairly accurately. How does one go about figuring the angle on the ply and also the angle of the cut to end up with a mitered hip corner?

[Rich]

You may be able to disseminate some information from the rafter calculator I have.
Roof angle calculator (http://www.construction-resource.com/roof_frame.php)
I think, if I remember how I made that damn thing, you can use the hip rafter miter and bevel angles to get what you want. Might do a test cut first though.. :)

[grumpydasmurf]

pitch degrees

1/12=4.5
2/12=9.5
3/12=14
4/12=18.5
5/12=22.5
6/12=26.5
7/12=30.25
8/12=33.75
9/12=37
10/12=40
11/12=42.5
12/12=45

[Rich]

That's fine for the angles of degrees of the roof slope. But I think he was asking for a pitch plus an angle along a valley or the ridge of a hip.

[opie1]

Yeah Rich, you are correct in that I need to figure out how to layout the
plywood, on a flat plane, and then the sawcut angle to cut it so when I put
2 pieces together I end up with a hip corner

[opie1]

Would the sawcut angle still be a 45 deg.?

[Rich]

I don't believe so.. in plan if you take the point and raise it.. i think it becomes something different than 45.. except in a special case of a 12/12 pitch.

[grumpydasmurf]

I know rich but knowing the slope cna help determine the other factors.

[Rich]

Yep.. for sure.

[opie1]

I think I'll do some experimenting with some scrap and see if some kinda' formula pops out. I once had to form a 2'x4'x2' deep slap blockout in a
concrete deck pour for the main power lines to come in and it required
45 deg. slopes, in at the bottom, to keep the stress off the conduits. One of
the guys came up with the formula for cutting the ply and called it a "hopper
cut". Again, like Rich mentioned, it probably works out better when you know
the angle to be 12/12 or 45 deg. I'll let ya' know if I figure it out....

[Jedadiah]

Are you looking for the difference in length across a 4 feet sheet??? Try www. roofbible.com. The site doesn't have the answers but thi book pretty much has them all.

THe DOL on a 12 hip is 33" 7/8 (Thats from a sqaure end of the the sheet), but I just remember that because we do them all the time.

Of course if your hips are running right, you could just measure the DOL on the first run and use it as a guide for the the rest.
However, that won't help with concrete. I shouls read a little deeper, before I respond...

[Joe Carola]

A simple way to figure out how much to cut off a sheat of plywood for your Hip or Valley would be to do this.

On your Rafter Square you have all your common rafter length per foot run measurements which is your Hypotenuse for all your pitches. Take that number for the pitch that your using and divide it by 12 and that answer you will take 48 which is the height of a sheat of plywood and divide it by that answrer and that will be the measurement in inches you will come in on one side of the sheat of plywood and snap a line to the corner and that will be you Hip or Valley angle for your sheathing.

For a 12/12 pitch roof as Jedadiah mentioned just simply take the 16.97 number you see on the framing square under 12".

16.97/12 = 1.414167

48/1.414167 = 33.94" or 33-15/16"

Or you can take the common rafter length and divide it by the common rafter run and that will give you your 1.414167 answer.

For a 8/12 Pitch.

14.42/12 = 1.201667

48/1.201667 = 39.94" or 39-15/16"

[R Birch]

Que Paso Joe C.? I see there is another forum to talk roofs on.

The Swanson’s “Blue Book” on pages 8 and 9 has a chart for sheathing cuts. It is based on the same math in Joe Carola’s post above. The framing square itself can be used to make these marks too using the “Side Cut of Jacks” scale.

Another way to find the “run” for 4’ sheathing is with the CM Calculator. Enter 4’ as the hypotenuse [Diag] of your preset pitch and then press [Run]. The result is the sheathing cut. This method works very well for odd pitched roofs that may not be found in most rafter book’s sheathing cut charts.

For sheathing cuts on Irregular Hips/Vals the CM Pro Calculator works well too.

Enter 4’ as the [Diag] of the pitch you wish to solve, press [Rise], store as rise for other pitch of roof, press [Run], result is sheathing cut for original, or first pitch, hip/val sheathing cut. Reverse the process to find sheathing cut for other pitch. :wink:

[Joe Carola]

What's up Richard? Are you staying out of trouble :wink:

I'm glad to see another forum like this. There's alot going on here. Your not going to cause trouble now are you :P

I wonder what way people are comfortable framing roofs here. I'm going to keep reading if my son doesn't want to wrestle me like he's been asking for the past 10 minutes. Are there alot of guys using the Construction Master Calculator?

Anyway hope your doing well. Any word or sight of Ken Drake? I know your not to far from him.

[R Birch]

Hi Joe,

I’m doing fine. 8) How are you and “Mighty Joe Young” doing? I haven’t heard much from him lately. :(

What do you mean, “Start Trouble?” You wouldn’t be referring to the old “Hip Drop”, would ya? :roll:

Oh well, like I said, “Never heard of it!” :wink:

It is good to see more contractor sites and forums. I wish Rich success here. :!:

I haven’t talked to K.D. in a while. Maybe he’ll stop in here some day.

[Rich]

Are there alot of guys using the Construction Master Calculator?

I've got one but never really used it for more than figuring concrete :)

[R Birch]

Rich,

IMHO, For onsite roof framing calculations it can't be beat!

Joe,

A lot of guys here use them. Not all though.

[Tom R]

Yeah, I carry the regular one in my truck, and the 'desk-model' in my office. I use it just about everyday for anything, everything.

[Joe Carola]

Are there alot of guys using the Construction Master Calculator?

I've got one but never really used it for more than figuring concrete :)

I'd like to here some of the ways some of you guys figure out rafters without getting the lengths from a book because they don't teach you anything or help you in situations where you have fixed ridge heights or framing an addition where the rafters have to land under the second floor windows etc. It's always interesting to know like I said in a previous post do some of you guys figure out rafters with a Framing Square, a Scientific Calculator or a Construction Master Calculator or Construction Master Calculator with Trig in it?

[Rich]

I've always used the framing square until I get into something I haven't had to figure out before. Then I'll go to my 1945 Building Estimating and Contracting books from the American Technical Society and read up on it.
If my mind still can't grasp it I go to Autocad and lay it out and get rid of as many variables as possible.
The image below is one that I hadn't done before - an ellipse. As you're well aware of - each rafter is a different pitch and comes in at a different height along the main doubled up truss. Took me a bit to figure out to where we could keep all the exterior fascias at the same height.

[Rich]

I apologize for the filesize - should have shrunk that down. Also - the gaps in plywood will be covered - we have another layout to go on yet.

[Joe Bartok]

Hi Guys:
Found your posts regarding roofing angles while surfing Google, and thought I'd register.
Visit my website at http://ca.geocities.com/xpf51/index.html, and click on ANGLE CALCULATORS.
To answer the original Hip question: Enter the Pitch, Pitch, and Deck Angle in a calculator such as "LAG." Your miter angle is 90-P2, the blade angle setting is C5.
Gotta go now, be back Friday!

[Cole]

Link is a no workie for me!!!!

[grumpydasmurf]

LOL Dejavu. I was just looking for this exact thread and I log in and see it at the top of the list! Excellent.

[Rich]

Link is a no workie for me!!!!

Remove the , at the end of the link :)

[Cole]

Link is a no workie for me!!!!

Remove the , at the end of the link :)

Doh!!!, Slaps self on head.

[Dragon]

I got a Construction Master IV because a lumberyard saleman gave one to me. Until then I had always figured rafter lengths the old fashioned way. I said what the heck and tried it.

I now own two Construction Master Pros. They will figure arcs. Very handy for figuring jams on arched or circle top windows.

If I need to know I need to know now, not eventually. Real timesavers and very accurate.

[Joe Bartok]

Sorry about the bad link! :oops:
I was on a computer at the local public library, and found the question at about three minute from closing time. Not much time to register, whip over to my e-mail to activate the account, and type in a response, and I forgout to actually make a "URL" out of the link. Should have known better!
OK, here it is again. If this doesn't work, just type it in your address bar.

http://ca.geocities.com/xpf51/index.html

If I understand your question, the problem is similar to the Gazebo hip roof in the Photo Gallery (the same photo is also embedded in the Excel worksheet Log Angle Generator). Download the worksheet, or use the online calculators Lag or LAG. Enter Main pitch, Adjacent pitch, and Total Deck angle.

Your answers are:
Miter line from the edge = 90-P2
Saw blade setting = C5

For those who enjoy math, browse the site and have fun. If anyone needs help or an explanation of the angles, fire away!

[Joe Bartok]

Here are some more Hip and Valley calculators.
Hopefully, I'll get the URLs right this time.

This one's fairly simple:
http://hpprgmr.home.texas.net/Programs/hip/hipValMain.htm

Steel-Link website:
Hip and Valley books (pdf files)
http://steel-link.com/2002/downloads/hip.cfm
From the same website, a neat little calculator (STEEL-VB6.zip)
http://steel-link.com/2002/downloads/other.cfm

Timber Framers Guild site:
There's already a link to this Hawkindale angles worksheet somewhere in this forum. The worksheet has been recently upgraded (Sept. 2004). There are also diagrams at this link; a picture really is worth a thousand words.
http://tfguild.org/tools/tool2.html
Background material and definitions of the Hawkindale angles:
http://tfguild.org/tools/hipart.html

Lots more information than needed to frame the average roof, but the calculators will work for just about anything that has a pitch, pitch, and a deck angle, such as the original concrete form question, or the angles needed to cut crown molding.

Have a good weekend! :D

[Joe Bartok]

Wish I had read more of the post here.

Joe Carola asked if alot of us use Construction Master calculators, and about methods of calculating roof framing variables.

The guys I generally work with use Construction Masters. They generally use over-12 calculations. I've tried these calculators myself, and they work fine, though they're a little limited in what they can do.

I use a Casio 7700GB programmable calculator. The biggest advantage is versatility; instead of being stuck with pre-programmed calculations, you can write and save your own custom formulas and calculations.

[Tom R]

That Casio 7700GB sounds pretty cool! What's it go for and whose got it? I deserve a new toy!

[Rich]

Yeah - same for my HP48. I've got my roof area calculation and cubic yard calculator programmed in (same ones as on this site).

[Rich]

Oh - it runs about 250 depending on where and what you get with it.

[Tom R]

Wow! 250? Wonder if the wife might want one for Christmas, - - hmm, - - no, I better come up with a better one than that! :D

[Rich]

LOL.. yeah I've tried that one before with a digital camera that she didn't want.

[Dragon]

I think I'll stick with my Construction Master Pro.

Luck to ya with the wife. :)

[Joe Bartok]

My programmable calculator is a few years old, and they've come a long way since. You can probably get one for eighty to a hundred bucks, with lots more memory and pre-programmed functions. And not necessarily a Casio (that wasn't an attempt to advertise a particular brand).

Just out of curiosity, did anyone try the angle calculation for the concrete mold that started this thread, and how did it work out? If you're not having any luck, post whatever values you're working with, or a sketch, and I'll take a shot at it.