Calculating Waste


Thanks! I appreciate your time and effort!


Hello Authentic_Dad, I was reading through this forum, and would love to see a copy of the roof waste spreadsheet your talking about here. I wan’t able to access any of the other links you have posted here.




I would really appreciate a copy of the formulas worksheet and an explanation on using it.
Thanks In Advance


I’m Jose, I thank you For you good information can you let me know if I can get a copy of you waste spreadsheet


Hey Authentic_Dad,

Would you please send me the spreadsheet if and/or when it is available.

Thanks so much for your insightful contributions


These are Dropbox links. You should be able to download the files. One is for the Waste Calc Spread Sheet itself, the other is for the instructions. I hope this helps some of you folks. Again, keep in mind what this is calculating is the waste for starter, cap and valleys. It does not make any allowance whatsoever, in the math, for trim scrap waste. It is not unusual, on a cut up roof, for the calculated waste to be larger than what was allowed by the insurance scope of loss. That’s how screwed up the practice of generically bundling in cap and starter into waste and assiging 10% for all gables and 15% for all hips is. Of course, that serves to allow the insurance companies to underpay their claims by a substantial amount.


Wow, Great read and info here.

I am currently going round with SF. It was a hip roof cut up with valleys. Of course you already know SF and their company line. Total was 51sq and they paid out at 59sq, when in reality we used closer to 66sq. Your spread sheet called for 12sq just for the H/R, Valley and Starter.

Thanks so much for putting in the amount of effort needed for this and then freely sharing it.

I could not however find the Drop Box link for the instruction page you mentioned. Can you please re-post?

Thanks, Preston


The instruction page is displayed in the post.


I gotcha, Thanks, I thought it was something separate. Thanks again for what you’ve put together.


love to see the sheet and instructions of how to use it. my email is



The link to download it is 3 or 4 posts above.


I am putting the finishing touches on a new waste calc sheet and expect to have it done in the next week or two. Have to do some more testing and make it prettier. It is much more robust than the one I’ve shared before. It will take into account every waste item on the roof, split out the number of squares required for cap and starter, split out the waste required for field shingles with cap and starter as separate line items and provide an overall total waste factor. It also has improved and more pages that support the argument against 10% for gable, 15% for hip as well as strong mathematical arguments and proofs why cap and starter have to be broken out as separate line items.

Will post here when I have it available for free download.


wow! looking forward to the new version. cant wait!


It’s done. Look in the other thread about waste.


Call it what you will, but if the Scope of Loss does not include a list of all items to be replaced (Hip & Ridge, Starter) it’s inaccurate/wrong. Aren’t all materials to be listed by description, qty and price?


What’s your point, you’re being rhetorical.


Sorry, thought I ended that with a question mark?


Yrs you did. It is a rhetorical question. Whether or not all estimates break out line items in detail is up to the person writing the quote. Insurance prefers to bundle in starter and cap with the field shingles using a waste percentage that is typically too low anywhere from 2 to 15%. I use the roof waste calc workbook two ways. First, it performs the math on the takeoffs that establishes what the waste percentage should be just on the field shingles and what the overall waste percentage should be. At minimum, it helps the user get paid for the correct quantity of materials.

There are also a number of sheets in the workbook that offer mathematical proof for why cap and starter should be broken out as separate line items. We are successful in accomplishing this more and more often by using this tool. Based upon feedback from many contractors who do insurance work, most aren’t very successful at accomplishing either of these. They end up eating the cost of additional materials in most jobs.


I appreciate the explanation.


at the risk of being redundant (in addition to rhetorical :slight_smile: ), I only see one link which takes me to the worksheet. You indicate another link (the other is for the instructions), where do I find this link?

And thank you for your thoroughness. We might get along well as we obviously think similarly.