Proper square footage + satellite estimate


Hello all…I need a few questions answered. How accurate are roof measurements that are taken by satellite imagery? Also, a contractor told me that I have 1500 square feet and another 10% will be added for waste…making it 1650 sq feet. I thought that if I need 45 bundles of shingles, then 10% was needed for waste…50 bundles in total. Your thoughts?



Interestingly enough I’ve never had to discuss bundle amounts with a customer. I’m not sure I care to either. Sure they see a square amount on paper but most don’t care to know what that means. The only issues I’ve ever had is a customer asking for a discount over the remaining bundles that our contract specifically states we own. I kindly explain to them again that we “over order” so that the job can be completed in a timely fashion and that the material is ours. I don’t even leave a bundle there to rot below their deck. I just ask who are you going to call should you have a problem with this roof? They say me and I say I’ll bring anything we need back then.

To answer your questions the eagle views aren’t always right but they are right enough to go by most of the time. And yes 15sq at 10% (assuming that’s the right waste) would be about 50 bundles. Then there’s starter, hip, and ridge.

Pick the guy you trust and let ‘er rip. Don’t over think it. If the guy is reputable he should know what he needs to get it done.

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We don’t even put a square amount on our contracts and customers rarely ask.



Yep, our contract doesn’t state squares but the scope does on claims. I do put a square amount in an estimate though, and figure that’s what everyone else does?



Satellite accuracy is mediocre, 5 to 10%. Aerial flyover images are much more accurate. 10% waste is minimum.

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Never give quantities to a customer. If you are over they expect rebate. If you are short do you think they will pay for extra material you need? Authentic, 10% waste on non insurance jobs? 30 square hard measurement needs 3 square for waste?



He said it was a 1650 SF roof so it must be a simple roof. And at this point, he seems to be looking for a rough idea. The contractor was silly for quoting any numbers as everyone has noted. Why try to determine or explain the complexity of true waste calculations when this basic concept is missed?



Thanks for your reply, Climb_One. The total base square footage of my residence is 1245 square feet with a roof pitch of 8:12. Now, I am multiplying 1245 s.f. by 1.2 which is the roof pitch multiplier…bringing the total square footage to 1495 s.f. Call it 1500 square feet ( 3 tab shingles ) which would equal 45 bundles of shingles. Add 10% for waste and that would bring it to 50 bundles…correct? For example, if the contractor is charging $4 per square foot, then I should be paying approximately $6000 to have my roof re-shingled…agree?

Now, I am being told that my total square footage is 1900 PLUS adding another 10% for waste, thus bringing the total square footage to 2100. This seems awfully strange.



You didn’t account for overhangs. Why don’t you just get 3 bids and choose the one you like? People don’t bid retail by the square, at least as far as you’re concerned. They bid the job.

When you go out to eat and order a steak, do you demand to stick your head up the cow’s butt in order to make your choice? You keep doing all the crap and every good roofer in the area will refuse to bid your job.



There is more involved to a roofing quote than square footage cost of shingles. There are flashings, ventilation, penetrations, ice shield, dumpester and dump fees to account for. As authentic said get 3 quotes pick the one you think will do the best job.

If a customer started asking me about how many bundles we were using I would just walk away. If you are using 3 tabs you will need more than 10% waste to account for starters and hip/ridge.