I have to frame a round roof. The round roof is 18/12. The major roof is a 9/12.
About 1/3 of the round roof will eventually lay on. I’m looking for the formula to create the oval layout lines on the roof.
HelllllllllllllllllP!
Here’s a picture of the round frame and the roof I’m laying onto. All I need is a small section of the arc.. the chord length would be about 10′ total.
I think I’m explaing that correctly.
(Edit I goofed on these pics….the second post are jpgs and I’ll reduce them again on the third post)
blue
Warning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything…including their own egos
Additionally, don’t take any political advice from me. I’m just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny…try them out)!
Edited 11/3/2004 8:03 pm ET by blue_eyed_devil
Replies
Oops, I forgot to convert them to jpgs.
blue
Warning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Resized smaller yet.Warning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Blue,
Ok, let's try this. Let's say your round room is 12' radius and 18' tall in the middle. Let's say that your 9-12 start from the center of the 24' room. The 2 roof slopes would meet 10 up the 9-12 rafter. Now if you take an ellipse and make the semi-major axis 24' and the semi-minor axis 10' and draw the ellipse, that should be the pattern. Then you could just cut it to fit the actual situation.
The way I figured the 5' up the rafter is with Autocad, but you could figure it really easy by setting proportions.
18+9=27 (both pitches added together) 18/27=.666667 .66667 x 12'=8'
8' run 9" pitch Diag = 10'
http://pic9.picturetrail.com/VOL293/2163851/5177572/72032511.jpg
I have no idea if this is right, but here goes :-) I'm off for about an hour to get something to eat.
Hey Blue do em all by eye!
No chalk line
No guard
No base(hacked off)
No fancy formula
Just the one good eye, that's all you need!
Doug, If I don't get a good answer, thats exactly what I'm going to do. The front 2/3 of the cone will be framed already. I'll simply create a round pattern, and fasten it to the inside of the roof, sliding the pattern out to catch two or three rafters. Then, I'll just cut them in by eye.
I fully intend to cut all the bottom pitches in by eye any ways. I'll have to make a small plywood "speed pattern" for the top plumb cut...although by the end of this roof I'll certainly be able to duplicate the cut. If my memory serves me right, the top cut of a 18/12 is the same as the level cut of a 6/12. I can make that level cut (the 6/12), its not a real common one for me, but....
I'd rather have an accurate line drawn on the 9/12 roof becuse when your carving one in, it helps to be able to use your miscuts on a different part of the layout. If I am only cutting one or two in at a time, I have less choices to use the part in an alternate layout position without stacking them up and storing them. I don't really have a lot of room up there to operate.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
There is a small section in Will Holladay's book about this where the major roof lays on the cone roof. If you want I can scan that page with the drawing and send it to you.
Also your psf files don't work for me. Do you know if I need a plugin? I see you changed the file to jpeg.
I like your duct taped cord :-), but a circ saw?
Edited 11/3/2004 8:04 pm ET by TIMUHLER
Sorry Tim, those are photo shops.
I already reloaded them to jpgs.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Tim, I knew I'd take some heat for that duct tape. It's not what you think. the tape is there because the rubber jacket got nicked. The inside is still intact. I'm waiting for someone to cut one of their yellow jacket cords so I can install a 20' lead on that saw.
If you can scan and post it or email it, I'll see if it helps. Anything will help!
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Blue,
Here is the pic. I realize some might get upset at posting this, but I consider it an advertisement :-)
If I understand you, your situation is opposite this picture. So you basically need the ellipse to cut out an lay on your 9-12. I have to think about that. I don't know how to figure it, but I'm going to think about it. This file isn't small, but I wanted it to be detailed
http://pic9.picturetrail.com/VOL293/2163851/5546331/72028167.jpg
Try this. http://pic9.picturetrail.com/VOL293/2163851/5177572/72028743.jpg
Edited 11/3/2004 8:30 pm ET by TIMUHLER
Tim,
In his picture at the bottom where the tower rafter intersects with the main rafter on both sides of the diameter that length would be your Major Axis and where the center of the tower rafter intersects with the main roof rafter that height would be your Minor Axis and then Blue can just draw it out on the sheathing right in place.
Joe Carola
Joe. help me out with the math here.
The major chord will be 10'.
That makes the minor chord....I don't know? Thats my problem...I don't know!
And you know whats funnier! I don't have a single carpenters book in here to look anything up! It's been many, many years since I've looked into my books...if I even have any left! I think I do...
...now where are those?
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Blue,
You said about 1/3 of the Tower Roof will lay on the Main Roof. There's probably no way for you to set a Tower Rafter in to see where it intersects with the main roof so you can figure it by knowing that 1/3 length and just draw a rise and run for both pitches with that 1/3 length until they intersect and that would give you your height as if a Tower rafter was there to intersect the main rafter which would then give you the measurement for the height of the Minor Axis.
Joe Carola
Okay, lets just say I'll be able to figure my minor axis height....
How do I create the ellipse?
I friggin lost...I'm just gonna cut it in by eye....no...I want to know how to draw an ellipse.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Blue,
Here is a link that shows how the string method for laying out an ellipse works. http://mathworld.wolfram.com/Ellipse.html
I use picture wire when I draw an ellipse.
Oh wow Tim...that's a lot of information!
Ill have to put that one on the desk top and visit it another time. I tried to print it out with that fancy moving drawing.....
Thanks a ton.
I'm getting too tired to read it...I'll read it tomorrow.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Blue here's a drawing of how to draw an Ellipse.
Joe Carola
Joe,
I don't think that I was very clear. I didn't take into account that Blue's round roof was about a 1/3 into the 9-12. I was just using round numbers.
It looks like in Will's drawing that the major roof lands about center of the cone roofs base. I just mimiced that (without the drawing ability :-)) to show how with 2 different pitches, you could get the semi-minor axis.
The base of the round roof would be the semi-major axis, and the diagonal number following the 9-12 pitch would be the semi-minor axis.
JOe, I think that little drawing will give me enough info to create an ellipse on my roof...I hope. I think it will.
I'll determine where the two roofs meet at the lowest point. That will be my major axis. I'll determine where the two roofs meet at the highest point...that will be my minor axis. I'll then use that string method...
Incidently, Frank and I were yakking about how to draw this ellipse. I mentioned the string thing and told him that I remember it being explained in my carpentry book that I used to go through the Union Carpenter Apprentice Program about 30 years ago...but I couldn't remember it because I've never needed it (I try to avoid round...around here, most of the round stuff is not profitable...wrong kinds of builders...). Anyways, up walks the newest member of our team and he starts explaining how to use the string method to draw an ellipse...! I think by tomorrow he'll have the exact explanation. I won't pull out this printout until he fails...I have a feeling he'll succeed though!
Thanks a ton!
I printed it out and its readable. Warning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Blue,
Take lots of pics!! I would really like to see how you progress and how it turns out. I'm a junky for roof framing (and framing in general) pics. I hope it goes well and have fun :-)
I sure will Tim. Thanks for that next link and picture, I printed it out too...All of this will be helpful.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Blue,
What's the diameter of your stairwell?
I assumed ten feet, giving you approximately a 9'-6" chord.
This would place the high point of the ellipse a horizontal distance of about 2'-3" from the edge or about 2'-9 1/2" up the plane of the roof. If your rafters are 16" OC, you would only have to consider about seven of them crossing the arc.
Your angle of the cone is about 56 degrees from the horizontal. One way to easily mark the rafters without a lot of math would be to attach your tape to the center of the stairwell by spanning with a 2X and hooking on to a nail in the center. Then hold your chalkline at the five foot mark on the tape, or whatever your radius is. Have a helper hold the string at 56 degrees and position the tape where the string will cross each rafter. Make your marks. You can use the framing square to get the pitch or the speed square to get the 56 degrees, or cut a piece of plywood into a 34-56-90 degree (18/12) triangle and place it on the end of a strip of furring which is the length of the radius, again attaching it at the center of the stairwell.
Les Barrett Quality Construction
Edited 11/4/2004 10:42 am ET by Les
Les, the diameter of the stair well is 12' 5.5" with a 12 projection past an 8 " brick detail.
Total span at wall: 12-5.5 or 149.5".
Total span overall: 189.5".
I calculate all my rafters using the outside diameter of my projection. The rafters will be 170.81". I will lean the first two against one another, so this will be my cut length.
The top of the fascia is level with the top plate (we already have it installed). Quick calculations tell me me that I have a 30" heel (height above plate at the outside wall line).
Heres a picture of the situation. The stucco siding at the side wall is properly positioned to receive the flashing from the finished roof.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
I don't know if you can read the numbers. I did this with what I understood from your posts, with about a ten foot chord of intersection and so on.
Will not try to explain to avoid confusion. You can probably pick out what you need.Les Barrett Quality Construction
I see it now Les. Thanks for those drawings. Your skill is impressive.
I'm noticing that your using 56 degrees and calculating each step. Is this possible to use simple geometry or do I have to use trig?
On site, I'm just going to establish the low points where they meet, which should be very simple. that will give me my major chord. The high point will be easy to determine using the simple math formula too. So, I have enough information...I just really don't understand it all..yet. I have to study that one website and maybe come in here and ask intelligent questions...instead of this grammer school stuff!
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Sorry to confuse. The 56 degrees is just the 18/12 slope. You can use a framing square in lieu of the speed square.
The piece of plywood with the 18/12 slope will do the trick when nailed to a 2x2 which is the length of your desired radius.Les Barrett Quality Construction
Okay...I got to the job this morning at about 10. Heres what I was looking at.
BlueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
I was this far at 4:30. Not my best day, not my worst!
I worked on the tower, Frank was working on the roof to my right, Carl layed most of the ply on the upper.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
This was my setup...a set of horses....a stash of 2x6's . The picture shows the first common. It has a 30" heel...I used some scrap osb to scab it together.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
I'm now just stacking the next one and using it as a pattern to make the next heel.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
I tack the rafter cutoff onto my first common and lay a scrap on. This allows me to figure how much I need to shorten the third common.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
The third common is 1 3/8" shorter according to my unscientific method.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Blue,
Keep on a postin' I love the pics :-)
At lunch, this is what I've got done. I'd fire myself if I was that slow! The truth is that I made some bonehead mistakes. I'm not good at multitasking. Working and taking pictures disrupts my concentration.
Remember the 30" heels? Welll, I nailed two of them onto the top of the rafter! In fact, if you go back to the pics where I had them stacked, you'll see that the two rafter ends were different!
Oh well, it suks to get old.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
This pic shows the fourth common being figured. After all that discussion about chords and strings, I basically did what I usually do.
I put a plumb cut on the fourth rafter...the one that will lay onto the existing roof. I'm using a slightly longer rafter, and have it resting on a nail, that is 1 3/8" down from the peak. As I slide the rafter up and down, the plumb bubble tells me when I hit the spot. I mark the spot on the roof, and mark the length of the rafter and then all I have to do is figure out what that bottom cut looks like.
It ended up being...a 90! No addtional bevel necessary!
Hooray!
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
This is how the first four members look. Its actually pretty simple..a piece of cake.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Eventually I get to this point. All the rafters are in. Theres three pics. The first shows the peak, the second shows the bottoms at the left side, and the third shows the bottoms at the right side.
It turns out that all of the layon rafters are all fairly square with relatively small bevels. I've cut them all in using a scribing method. I used my framing square to make the pattern for the first four. I use the square for the first "hip", out of guilt, then got impatient and freehanded the rest, including all bevels and angels on the tops. It turns out that the top plumb cuts, which is an 18/12, is the same as a level cut on an 8/12 (duh! do the math!). I've cut so many 8/12s in my career that as long as I don't think too much about it as I'm doing it, I can just cut them on auto pilot. If I begin to think too much, I freak myself out...
One of the next eight "hips' was an 8.5...maybe an 8.25. I nailed it up anyways...now the house will only stand for 200 years instead of 250...I'm not going to lose any sleep....
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
These two final pics show the peak from two angles.
The lumber layed together nicely...its a fine pack of toothpicks!
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Mission Accomplished!Les Barrett Quality Construction
Blue,
Looks really good. Thanks for posting the pics. I hope you don't mind, but I'm saving them :-)
Chapeau! I'm impressed.
Just reading the questions in this one made me dizzy.
Nice job, Blue.Dinosaur
'Y-a-tu de la justice dans ce maudit monde?
now comes the hard part, ya just got to deck that thing>g
No, actually I think you have done the hard part.
Thanks for the pictures, its amazing what one can do with a little common
sense, so I guess that leaves me out cause you lost me a long time ago.
Keep on boogerin.
yeah, now he's got to deck it, and the roofer's got to somehow flash that superweird valley that he built.
David, we will be putting a saddle behind the tower. If I was the roofer, I'd want one...and so it shall be done. As a general rule, I am very conservative when it comes to creating potential leaks. I never feel bad "wasting" my precious time putting in saddles.
I save seconds on everything early in the game, then I have minutes to give back on the important things. I could get by without the saddle, but I wouldn't feel right about it.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Looks good Blue. What are you sheathing it with? I framed one 2 years ago with a 14' diameter 21/12 with 32 rafters and I sheathed it with 2 layers of 3/8". How many rafters did you put in?
Joe Carola
Joe, I ended up putting in 16 rafters. I considered putting in 16 more jacks....a coupla feet long, but decided to wait and see how the plywood formed. I reasoned that the plywood is going to be relatively tensioned and more rafters might be overkill.
I'm not big on overkill.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Joe, somehow I managed to dodge the sheathing duties of that roof. This pic shows Frank is on the trak working with the smoker Carl. They are laying 4x10 sheets of 3/8 exterior ply. We intend to only lay one layer unless some reason presents itself to do it twice.
The second pic shows the progress at lunch time.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Blue, you probaly already know this but for those that
have not had to deal with one of these.......
your roof sheathing cut at the facia would be....
total rafter length + total facia thickness (measured on your 18/12)....
cut the roof sheathing on a radius with that number,it will match.....
nice looking project.......regards
Thanks for that tip Caridaceagle.....but you offered it up a little late! And no....I didn't know that!
But......luckily the apprentice did! It seems that his public education actually taught him something and when I got there in the moning, he had already started precutting the sheets.
Here's a pic of him doing that.
The second pic shows the precut sheet loaded onto the skytrak ready to go.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
This final picture shows the completed tower. The guys are just fininshing the saddle behind it.
They said that they had to tweak one of the rear rafters...they just had to bang it over about 3/4" to put it into the proper plane. I actually had anticipated needing to tweak more of them because I floated all of them in by "feel"...I nailed the tip of the rafter and let it come down and create full bearing on the plumb cut..then I swung it into the roof.
I did learn something...how to cut the ply.....
blue
Warning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
That apprenti. sounds like a keeper...
unless he's showing us old guys up all left,right and centre...lol
then he is just annoying....regards
Bingo Cardiaceagle! YOu got the formula right.
I'm sending you a box of milkbones!
blue
Great I'll have to share them thou....
Blue,
Everything looks good but I'm curious about one thing. You said you had a Diameter of 189.5" to the outside of the projection and you told me you only used 16 rafters that would give you 37-3/16 o.c.
Your diameter without the projection at the plate line is 149.5" that would give you 16 rafters @ 29-3/8" o.c. at the plate line. Don't you think that's to wide?
Joe Carola
Edited 11/6/2004 9:12 pm ET by Framer
Your diameter without the projection at the plate line is 149.5" that would give you 16 rafters @ 29-3/8" o.c. at the plate line. Don't you think that's to wide
Joe, under most circumstances...yes. As I mentioned, I decided to wait to put additional jacks in until after the first row of sheathing was installed. There's three mitigating circumstances that afffect our decision...ther relative steepness of the installation, the tension caused by the curvature, and the fact that the bottom of the ply (which is the widest part) is solidly fastened to the subfascia.
Joe, you're pretty good at math...what is the smallest possible length jack that I would need to "properly" frame this roof at 24" oc.? Or let me put it anyonother way....If I installed one more jack at 24" oc, and had a 4 3/8" odd span, what length is that 4 3/8" jack?
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Blue,
You said, "If I installed one more jack at 24" oc, and had a 4 3/8" odd span, what length is that 4 3/8" jack?"
If your going to do that I would just install them in the center of what you have now.I would install 14-1/2" blocks at whatever point they land and at your plate line your centers are 29-3/8" so I would put rafters at 14-11/16" centers giving you 18-5/8" centers at your fascia line.
Even though you have your sheathing nailed on top of the fascia that's still to much space between rafters to nail whatever kind of roofing when your using with only one layer of 3/8" sheathing.
Joe Carola
Joe, that sheathing was tight as a drum...believe me, it wasn't going to sag!
You're dodging the question. How long would that jack be?
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Blue,
I wasn't dodging the question at all. I was just giving you an answer to the way that I would do it as I know you would but if you think that those big centers are fine with 3/8 sheathing and all you want to do is add a 4-3/8 jack that's fine also. I would say it would be around 40-1/8" to the plate and 76-1/4" to the fascia.
Joe Carola
Blue,
The one that I did was 14'4" diameter 21/12 the plans called for minimum 16" centers with 2 layers of 3/8" sheathing. I wound up with about 16-7/8" o.c. because of the circumference. I just ran all 32 rafters into each other. These pictures are garbage because I took them when I was done sheathing with a throw away camera.
http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=27734.4
Joe Carola
Edited 11/7/2004 11:28 am ET by Framer
A friend of mine had to put a new shake roof on a cone a while back. He ask if I had any tips. I had him put a spike in the peak, and hange a story pole on it which had the height for each course marked on it. It could piviot all of the way around, and was a guide for plumb cuts for the side angles also.
He did a nice job, and said it saved him a lot of guess work. The roofer can nibble off the back whenever he is through with the front, and the other roof is in the way.
Les, we discussed that method....Holding a constant circumference and plumbing down to the 9/12 roof. Ultimatly, if I can't determine a fool proof easy way to use my stringline, I may just do that.
I hope I don't have to carve too many into that roof. I'm not really that good at odd coupound angles. In some situations I do quite well, others very poor. If I do poor, I start with a small pattern to give me the "gist" of the cut, then fine tune the actual one.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Blue,
Plumbing down from a constant circumference will not work because you will be projecting the intersection of a cylinder with a plane. You need the 56 degree angle on the end to project the intersection of a cone and a plane. It will trace a different curve on the roof.
Les Barrett Quality Construction
Les, now you confused me again.
I'm imagining a giant 12 foot diameter drill bit. Because I'm superman, i hover overhead and drill a giant hole through the center of the cone. As it hits the 9/12 roof, it would put the precise.....
Oh...no it wont.
Maybe it will.
I'm just no good at circles...
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Joe,
I revised my drawing to look more like yours :-) This is what I was trying to convey, but I'll tell you, I'm not that experienced at this and the last 3 days have been total hell. The foundation of the house we started Monday was all messed up. J-bolts in the wrong spots, all the piers were in the wrong place and then they didn't get the concrete heights right so we had to hang the floor joists in the foundation. It was about 100 minimum hangers, I lost count. We broke off that job to finish some framing on another job and when we came back today, the concrete sub had taken one of our girders down and moved the piers so we had to set it up again. Anyway, I'm not thinking to clearly today. At one point I launched my hammer. Felt good to blow some steam off :-)
http://pic9.picturetrail.com/VOL293/2163851/5177572/72046626.jpg
I prefer to throw my saw or nail gun...it has a much better impact and effect.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Blue,
Here's a Formula when you have the span for two different pitches that will intersect with the same rise and this formula will give you the run and then you can get your diagonal the will be your Minor Axis.
I just used 72" as the 1/3 of your roof for the span.
Joe Carola
Just updating you on that roof Joe. We have rain today...I'm rained in!
I did study that drawing on the throne today and I believe I will be able to accurately determine the rise and runs. Drawing the actual ellipse might be another story....
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
Blue,
Once you've figured out your Minor axis can you tack a couple sheets of plywood together because I think that you said your Major Axis is about 10' and just draw the Ellipse on them and cut it out and then come in from the cut out 3 or 4" and just eyeball the second cut just so you can carry a small pattern up to the roof and then scribe it.
Joe Carola
That was my plan Joe, If I couldn't scribe it directly on the roof. It appears that the string method will be easy to scribe directly onto the 9/12 roof, once i locate the highestpoint.
All of this information has been helpful.
Actually, I was hoping someone had a speedellipse tool in their bag!
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
I know a good framer that can just eyeball the Ellipse his name is Blue.....;-)
Joe Carola
Instead of generating the ellipse from calculating the axes, you could do it with a story pole.
You plumb up a story pole where you want the top and center of your tower to be. Then cut a very true circle out of plywood, say with a six foot diameter. Slip the plywood on to the story pole so that it is level and centered. Set the height of of the disk so that you get the correct pitch when you pull a string from the top of the pole to the edge of the disk.
Now you can mark the intersection of rafters by pulling the string to any length and noting when the string just contacts the disk.
Paine, that was one suggestion that the guys discussed. Then, for some unexplicable reason...they sent me up there.
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
OK I read all of the advice, and went away thinking that you had gotten good advice, but then while eating I came to realize that your advice is possibly mistaken.
Consider this. If the 9/12 pitch were to slice through the total cone, the major axis would be along that line, and its semi length would be where it intersects with a plumb line from the center of the cone/circle, and the minor axis would be where that plane would slice through the top of the 18/12 pitch if they were projected on down that far.
The shape will be a cord which slices off the pointy end of an ellipse, not a semi-ellipse as what was very well described above. I will check back and see how this is going. If you get out to the job in the meantime, try to get some precise measurements. About a third may be fine for horse-shoes, but this needs to be more accurate than that. I hope this helps, Keith
Keith, getting the accurate measurements would have taxed my brain beyond it's ability...before I got all the great pictures from the guys.
I tossed out that 1/3 figure just so I could get started on the theory...and figure out what I was supposed to measure! That part worked.
I also reasoned that if I knew what numbers I needed to draw a partial chord, I could draw it starting from the highest point, which I knew I could find quite easily. I was right about how easy it was to find that point...in fact it was quite a bit easier than I originally thought!
blueWarning! Be cautious when taking any advice from me. Although I have a lifetime of framing experience, some of it is viewed as boogerin and not consistent with views of those who prefer to overbuild everything...including their own egos
Additionally, don't take any political advice from me. I'm just a parrot for the Republican talking points. I get all my news from Rush Limbaugh and Fox and Friends (they are funny...try them out)!
surprised no one said to erect a big triangle (calculated by the latitude of your location) and use it like a sun dial, mark the shadow every hour and nail a rafter there {G}
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