# Surface area of roof

Page 2 of 2
• posted on April 12, 2016, 1:07 pm
snipped-for-privacy@slp53.sl.home (Scott Lurndal) writes:

Argh. hypotenuse = cos(90) x adjacent

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• posted on April 12, 2016, 3:27 pm
On 11/04/2016 2:17 PM, Scott Lurndal wrote:

That's unnecessarily complicated. It's a 5/12 roof pitch therefore the roof area is 13/12 the base area. Simple! Graham

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• posted on April 12, 2016, 4:55 pm
On 4/12/16 10:27 AM, graham wrote:

Explain that in detail again, if you don't mind.
--

-MIKE-

"Playing is not something I do at night, it's my function in life"

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• posted on April 12, 2016, 7:08 pm
On 12/04/2016 10:55 AM, -MIKE- wrote:

The slope length on a 5/12 ratio roof is 13 (5x5 + 12x12 = 13x13). In other words the roof distance from crest to wall is 13/12 (1.0833) the size of the floor measurement So if the floor area of the garage plus overhang is LxW, the roof area is LxW x 1.0833 for a 5/12 roof pitch.

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• posted on April 11, 2016, 9:51 pm
On Monday, April 11, 2016 at 2:06:39 PM UTC-5, dadiOH wrote:

dadiOH, check out these keyboard shortcuts: http://www.nouilles.info/keyboard_shortcuts.html
Sonny

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• posted on April 11, 2016, 10:44 pm
On 11/04/2016 1:06 PM, dadiOH wrote:

Surely the area is bxcx13/12 Graham

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• posted on April 11, 2016, 8:56 pm
On 4/11/2016 10:29 AM, swalker wrote:

Simple ... model it in SketchUp, select the face, and right click the context menu for "area/selection".
;)
--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net

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• posted on April 12, 2016, 4:29 am

Sometimes that is literally and by far the fastest way to get that information!
Puckdropper

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• posted on April 12, 2016, 6:01 am
Hmmmm....
Feeling a little old fashioned here. I do a lot of roofing within my contr acting business, and I get on the roof and measure it. If it is a shotgun roof, no need.
But if it has a gable or two that intersect the main roof (which are probab ly at a different slope) you will pick up the exact measurements you need. This will also allow you to consider large "saddles" or diverters behind c himney,and pick up any considerations for any other structural features.
You can check your skylights, measure valleys for sheet metal, count your p ipe jacks and make sure any other sheet metal features and venting (think s quare vent hood caps) are still serviceable as well as measure for storm ca ps, etc. Also, the number of valleys (and their sizes) as well as differen t features will require that a factor is added for the shingles needed to p roperly roof/seal the valleys. You can also look for damage to the existin g surface to make sure that unseen leaks that haven't presented inside the house have not caused decking or structure damage.
Yep... it's on the roof for me.
Robert

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• posted on April 12, 2016, 1:28 pm
On 4/12/2016 1:01 AM, snipped-for-privacy@aol.com wrote:

It takes two these days.
Carlos gets on the roof and measures. Calls the numbers down to me. I write them down and do the math.
Thought I'd never get to this point ... ;)
--
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Wood Shop: www.e-WoodShop.net

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• posted on April 12, 2016, 5:35 pm
On Tuesday, April 12, 2016 at 8:28:40 AM UTC-5, Swingman wrote:

I don't get on them anymore unless they are no more than 7/12. I won't get on a metal roof unless it is 5/12 or less without some safety gear. I hav e alternative ways of measuring a high slope roof from taking detailed phot os (standard shingle is 36" wide with a 5" reveal), but can also include ha ving Hector (if needed) measure them for me if it is something nasty. If i t is one of those gawdawful Tudor styles with the 12/12 feature roofs on to p of high slope hips, I pass.
I slid off a 6.5/12 sheet metal roof about 10 years ago and went all the wa y to the ground after sliding about 40 feet. I didn't break anything, but thought I was killed. I hit like a bag of wet sand, and stayed in place fo r about 5 minutes after impact to make sure I was OK. Lesson learned?
Don't bounce like I used to. That falls in line with a lot of other lessons I am learning along the way like the fewer 12 hour days the better, don't eat too much at lunch or I will be sleepy all afternoon, not too much hot s auce when going back out to work on the job followed by keeping a jumbo bot tle of antacids in the truck, bring my glasses to the job, stand on a ladde r not a paint can, don't overreach from the ladder, make a list for the day 's goals so I don't forget things to do, don't stop for a late lunch as I m ight not go back to work... how things change.
Robert

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• posted on April 12, 2016, 6:00 pm
13/12 works because it is an approximation of the cosine of a 22.5 degree angle (which is the angle for a 5/12 roof). Saves roofers from requiring trig functions on their calculator.

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• posted on April 13, 2016, 12:36 am
snipped-for-privacy@slp53.sl.home (Scott Lurndal) wrote in

The angle of a 5/12 roof is arctan (5/12) = 22.62 degrees; 13/12 is *exact* (as has been pointed out by several others in this thread, 5-12-13 is a Pythagorean triple).
Perhaps you meant to say that a 5/12 pitch approximates a 22.5 degree angle?

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• posted on April 12, 2016, 6:34 pm
On Tue, 12 Apr 2016 10:35:55 -0700 (PDT), " snipped-for-privacy@aol.com"

My previous house had a 15:12 pitch on the main house (12:12 on the garage). Might just as well be vertical. I was surprised at the high pitches but found that it was code for the area. No idea why. My current house is probably at least 12:12 but I've never bothered to measure.

Ouch! Sound like you were living right!

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• posted on April 13, 2016, 5:06 am
On Tuesday, April 12, 2016 at 1:34:15 PM UTC-5, krw wrote:

Don't I know it! I was pretty sore from it, but I have one guy that I know that broke his back when he fell off a lower eave roof and another that sm ashed his shoulder to the point if being in a body cast to hold it in place . Dumb luck, nothing else.
I am wondering if the reason you have such a tremendously high slope roof i s because of deed restrictions (trying to maintain some continuity of style in your area) or if you have a lot of snow and ice? Even for snow and ice the requirements are much lower, say 8/12 or so.
We have very little to no snow, rarely any ice on roofs, so unless it is fo r architectural purposes, we never see those super high slope roofs.
Robert

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• posted on April 13, 2016, 2:21 pm
On Tue, 12 Apr 2016 22:06:40 -0700 (PDT), " snipped-for-privacy@aol.com"

Must be. No snow or ice to worry about in AL or GA. ;-)
I thought it really weird since wind can be a problem (hurricanes). I never expected to see high pitches in the South but it's the norm.

Well, they shingle walls, too. ;-)

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• posted on April 12, 2016, 7:20 pm
On Tuesday, April 12, 2016 at 9:28:40 AM UTC-4, Swingman wrote:

I was watching ATOH a few weeks ago. A (young) chimney guy was putting a cap on what appeared to be a double chimney, so you know the cap was fairly wide.
It was an older 2 story house with full attic, so he was pretty high above the street. He had a step ladder leaning up against the peak-side of the chimney, i.e. the narrow side of the chimney in this picture.
He was not secured by any straps. He lifted the cap over his head and simply walked up the step ladder, plopping the cap on top of the chimney. One gust of wind as he was walking up the step ladder and he would have been on the street.
I almost crapped my pants just watching him.

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• posted on April 13, 2016, 2:50 pm
On Mon, 11 Apr 2016 10:29:40 -0500

show what you tried so far

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• posted on April 13, 2016, 4:37 pm
The past few years the roofing contractor I use uses these guys, and presents their bid based on satellite imagery/Aerial Measurement Technology:
http://www.eagleview.com/Industries/Commercial/Construction.aspx
http://www.eagleview.com/Portals/0/PortalContent/PDF/CS-118WRCover2012.pdf
When I meet them onsite to discuss material, style, etc, they're already ahead of game, just have to plug in the numbers.
--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net

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