Homeowner: Estimating Roofing Squares

I was hoping someone would take a couple of minutes to help me estimate the number of roofing squares required for a small house. The estimate given to me seems quite high for such a simple job, and unfortunately getting a second opinion right now is hard, we’ve been hard hit by storms. I have a diagram of the house footprint, but I can’t paste it. Here is what I have: total square footage of the house and garage is 1322sf. The house is “L” shaped, and to make a rough drawing I’ll give dimensions (and directions) E->W 48’, S->N 36’, W->E 19’, N->S 14’, W->E 34’ and N->S 22’. The roof pitch is quite low. I have calculated 2 different ways: using a formula I found on a roofing site and also a “rule of thumb” , square footage x 1.3. Those 2 numbers were within 10% of each other; Even throwing in 10% waste and an addition 4 squares for valleys, etc., the estimate is almost 50% over that. I wouldn’t want anyone trying to tell me how to do MY job, but I don’t want to be taken advantage of, either. Thank you in advance! -Mitzi

If you can send me the address of your property or will post it, I can use Pictometry to give you a very accurate estimate for what your materials should be. I will post the caveat this depends upon you being located in an metro or suburban area. Pictometry images are often not available for rural areas.

The address is 920 West Hughbert, Norman, OK 73069. Thank you!

Is it the one witht he pickup in the driveway?

[attachment=0]920 W. Hughbert.jpg[/attachment]

If so, waste might approach 20% or so.

This site says I don’t have the required permission to view attached files. The roof is brown, brick is orangish. Property is on South side of street, another house to the East, landscaped & empty lot to West.

The google maps image is off by two houses. The property is 2 houses to the west. Red car and Red truck are parked in a single car driveway.

The image posted by tinner666 marks the wrong house. Should be two doors down to west.

The flat roof area is 1,814 SF. Looks like the pitch is 3, perhaps 4. Your multiplier would be 1.03 for 3 pitch. That gives 1,868 SF of roof area. Hip roof, 15% waste results in 21.49 squares. Round up to 21 squares, 2 bundles. I took a screen snapshot from the Pictometry screen I used, I’ll try to figure out how to show it here.

[attachment=0]920 W. Hughbert.jpg[/attachment]

http://www.roofing.com/forum/gallery/authentic-dad-a367/roberts-roof-image-t1557.jpg

Yes, that is the right house!

I was quoted 30 squares, and since this will not be reimbursed by insurance an accurate estimate is especially important to me. I understand the measurement the roofer gave me was an estimate, but being almost 50% high is too much. I really appreciate your help. Now when I call another roofer I’ll have a professional estimate to cite! Thank you!

You also have about 3 sq of starters and capping, and lose about 1.5 bundles in that valley. Which puts you around 25 sq in total.

Some estimators are good, and some can’t count for the life of them. I have seen estimators be 10sq out on a 50sq house and then send 8sq too much for a 35sq house. 5 sq off isn’t all that bad, they might be willing to reimburse you for any extras (doubtful, but worth a try lol).

[quote=“bcdemon”]You also have about 3 sq of starters and capping, and lose about 1.5 bundles in that valley. Which puts you around 25 sq in total.

Some estimators are good, and some can’t count for the life of them. I have seen estimators be 10sq out on a 50sq house and then send 8sq too much for a 35sq house. 5 sq off isn’t all that bad, they might be willing to reimburse you for any extras (doubtful, but worth a try lol).[/quote]

No, that isn’t the case at all. The 15% waste will pretty much cover it on this simple roof. I’d bet you good money one of our crews could replace that roof with 22 squares and have half a bundle left over to give to the HO.

base on 1814 sq sf i agree with dad 22 sq eazy! any more then that i have to think hard about using that sub again.

Oh, so you count starters, caps and valley shingles as “waste”?

[quote=“bcdemon”]

Oh, so you count starters, caps and valley shingles as “waste”?[/quote]

I did in this case to keep it simple for the HO inquiring. There’s not 15% of trim scrap and valley under layer on this particular roof. This roof has 191 lf of perimeter, so 2 bundles of starter. There’s 140 lf of hip & ridge, that’s 5 bundles of cap. There’s 17 lf of valley. 1 bundle. You therefore need 2.67 squares for starter, cap and valley under layer. Now keep in mind that assumes ZERO utilization of trim scrap for cap. Let’s assume you can recover 2 bundles of cap from trim scrap, you have 2 squares for starter, cap and valley under layer. That would leave around a square lost in waste for trim scrap which on this roof, wouldn’t be that far off. At worst, this roof would need 22.67 squares. If your crew couldn’t do it with that, it’s time to find another crew.

Don’t be confused, if you send out 25 squares for this roof, wouldn’t be surprised if many crews found a way to use most of it. Send out 22.67 squares and let them find out at 3:00 PM they can finish the roof today or come back and finish tomorrow, and no more material is going to be made available today, and watch how many times they complete the roof and have a broken bundle left over. We use the waste calculation sheet I developed on every roof, you’d be amazed with our ordering accuracy.

Estimating total materials is for the contractor to decide after he’s awarded the job. Estimates usually are for a set price based on total square footage, period. Roofing contractors in Miami usually include a roof diagram with dimensions and sq.’ The insurance company isn’t interested in a squabble over starters, cap, waste, etc.
All that aside, SQ FT X .03 X 15% should be real close for the roof in the photo.

Roofer Mike

http://www.roofermikeinc.com/Re-roofs_and_Repairs.html

if you go up there and run a wheel tape then put the numbers on the roof drawing you made then you can get it exact.