I went to measure the apartment complex today. They have 8 buildings. We hand measured 9 seperate roofs on one building. After measuring the one building by hand, I did L x W X multiplier. The multiplier I found online for 7/12 is. 1.274. Someone I asked said 1.66 which made a rough difference of 1,000 sf. When I used 1.274 I came within 60 sf of hand measuring for an hour. Are either of these multipliers right?
Thanks in advance
Bill McMahon said
Oct 6, 2012
Hi John: I've been in the roofing business for 13 years. Whether we're doing a roof replacement or cleaning our guys measure every job from the ground. We then use a pitch multiplier and a waste factor (replacement only) depending on the style of home. The key to this working is first and foremost to get the pitch correct. I recommend a $10 protractor/angle finder that you can buy from any Ace Hardware or Sears. Place the protractor along the bottom edge of the rake board or on the roof itself. You can also place it against the underside of the deck in the attic whichever is easiest to get to. This will give you a precise measure every time. For technology geeks, you can download an app called Pitch Gauge 2.1 for your iPhone/iPad (maybe Droid?) that uses the camera to calculate the roof pitch. I would recommend field testing it to get the hang of it before relying on it for pricing. For an added cushion, I eliminate odd pitches since they are rare in my area and are usually the result of a mistake. The next most important measure are the actual dimensions. On the rake end, make sure you measure from roof tip to roof tip and not the foundation. Otherwise you will come up short. If it is a hip roof, add another 10% AFTER applying the pitch multiplier. Below are the multipliers we use. I hope this helps.
Thanks Bill, This particular set of buildings are built like I've never seen before. One end isn't as wide as the other end. If you looking at the end of a rectangular building with an addition at the end making the building look like a golf club, Imagine every so many feet a section is either moved forward or backward. I have the app multiplier. One building had 9 seperate roofs, that is why I measured each one on that building. I may just go off of those measurements of the one , for each other building except the office which is smaller. With the weather here I have maybe 6 weeks left to do any roofs this season. I'll admit this is quite a large job for a new guy but the building that I did the demo on has the most GM. What I might loose on that one for time and material I'll make up on the other 7 buildings. Thanks for the input John
I went to measure the apartment complex today. They have 8 buildings. We hand measured 9 seperate roofs on one building. After measuring the one building by hand, I did L x W X multiplier. The multiplier I found online for 7/12 is. 1.274. Someone I asked said 1.66 which made a rough difference of 1,000 sf. When I used 1.274 I came within 60 sf of hand measuring for an hour. Are either of these multipliers right?
Thanks in advance
2/12 1.01
4/12 1.05
6/12 1.12
8/12 1.20
10/12 1.30
12/12 1.41
14/12 1.54
16/12 1.67
This particular set of buildings are built like I've never seen before. One end isn't as wide as the other end. If you looking at the end of a rectangular building with an addition at the end making the building look like a golf club, Imagine every so many feet a section is either moved forward or backward. I have the app multiplier. One building had 9 seperate roofs, that is why I measured each one on that building. I may just go off of those measurements of the one , for each other building except the office which is smaller. With the weather here I have maybe 6 weeks left to do any roofs this season. I'll admit this is quite a large job for a new guy but the building that I did the demo on has the most GM. What I might loose on that one for time and material I'll make up on the other 7 buildings.
Thanks for the input
John
AC