I am planning on building a storage shed, and know everything that I need to purchase, with the exception of how much roofing materials. I am going to use 30 lb felt and 3 tab shingles, and the roof will be 170 square feet. How do I calculate the # of rolls of felt and the # of bundles of shingles that I should purchase?
Hey trixie, welcome to the Home Depot Community!
Standard 3 tab shingles (25 year warranty or less) cover 100 square feet with 3 bundles. Pricier (usually 30 year shingles are heavier, and you need 4 bundles to cover 100 square feet. I will assume that you are getting the standard shingles.
To cover the bulk of the roof: 170 sq ft / 33.3 sq ft / bundle = 5.1 bundles.
For the eaves you need one reversed layer from end to end, as well as along the rakes from ridge to the eaves. I will make up sizes so you can see how to do it and adapt your measurements:
Assume each half of the gable roof is 10 ft long (eave) by 8.5 ft high (rafter length or rake)
You have 1 eave and 2 rakes for each set of rafters.
So (8.5 x 2) + 10 = 27; 2 sets of rafters (27 x 2) = 54 feet.
Each shingle is about 3 feet long, and there are 21 shingles per bundle, or 63 linear feet/bundle.
So 54 ft / 63 ft / bundle = 0.86 bundles.
Last is the ridge: You will need about 24 ridge caps for every 10 feet.
There are 3 caps (tabs) on each shingle, so 24 caps / 3 caps / shingle = 8 shingles or (8 / 21) = 0.4 bundles.
OK. Add them up (5.1 + 0.86 + 0.4) and get 6.36 bundles.
On a big job add 5% waste, 10% on a small one: 6.36 x 110% = 7 bundles.
Now that I’ve gone through that, buy 8 bundles and return the extra one if you don’t use it. :smileyhappy:
One roll of 30# felt covers 216 square feet. You should be good with just one.
I hope this helps,
Newf