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How To Measure A Hip Roof From Blueprints

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Old 02-02-2018, 04:54 PM   #21
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Re: How To Measure A Hip Roof From Blueprints

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Besides using 1/2 the BxH I often used rafter run by average width in the middle. Alway favor to a wider point a bit covers waste. I found it pretty consistant
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Old 02-02-2018, 05:05 PM   #22
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Re: How To Measure A Hip Roof From Blueprints

What's the length of the right side?
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Old 02-02-2018, 09:43 PM   #23
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Re: How To Measure A Hip Roof From Blueprints

Back in the day, I used to figure hip to be the same as a gabled roof. Hips are less area than gable, but make much more waste. It's close to a wash. It was always pretty close.
So if you know the gutter to gutter, & the pitch, just use the slope gain factors above to get multiply the total horizontal width x slope gain for roof area.
gutter to gutter horiz dim = 30 ft
roof lth = 50 ft
30 x 50 = 1500 sq ft on level footprint.
1500 x 1.054 slope gain = 1581 sq ft of roof area
Slope gain = the hypotenuse of right triangle divided by the base.
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Old 02-03-2018, 10:16 AM   #24
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Re: How To Measure A Hip Roof From Blueprints

Maybe it's too late and OP has flown the coop???

Measuring a roof from drawings can be done with a high degree of accuracy, regardless of hip or gable by using the foundation plan and an account for roof overhang.

Break the foundation into rectangles. Add the overhang to the lengths of the sides. i.e. A 24x24 garage with one foot overhangs would be 26x26. Determine the square footage of each rectangle. Take the square footage and multiply by the pitch factor.

If different sections of roof have different pitches, then apply the associated pitch factor for the pitch of each section.

Add the results together. This will damn near the exact square footage of roof surface. Add one square foot for each foot of hip and ridge length.

Depending on the complexity of the roof and the ability of the crew to conserve material, determine a waste factor. Waste factors will be higher on hipped roofs and roofs with a lot of valleys.

A straight up and over gable is safe to estimate at 2%-4% waste. Moderately cut up roof between 5%-10%. Excessively complex may go close to 15% (some unforgiving materials may exceed this).

Areas covered with bitch hips can be accounted for by using a pitch multiplier somewhere in between the steep and the lesser pitched slopes.

The above directions will get you roof square footage quickly and accurately. The way to lose money on a roof is by ignoring the details such as valleys, flashing, masonry interfaces, small sections requiring lots of starting and edge work, and all the other details that make a roof a pig. The details on a roof have to be considered using elevations and schedules provided with the drawings.

You can always factor "pigginess" into your square price, but it's safer to know what the individual details are and price them as such.

Last can quickly determine an approximate coverage area using the method above if you were to consider the foundation as one large rectangle.......while measuring, one visually (mentally) fills in the areas like a puzzle to create said rectangle. Once determined, allow for overhangs a proceed with Length x width x pitch factor. If the roof has multiple pitches, try and assess an "average" pitch and use that multiplier. This is useful when you need to come up with a quick budget for different roof materials which vary greatly in price.


Above all, a good roof

Last edited by Mr Latone; 02-03-2018 at 10:30 AM.
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