ContractorHandbook

How Many Shingles for a 36x48 Pole Barn Roof?

Roofing squares needed

20 squares

A 36 by 48 foot pole barn at a 4/12 pitch with ten percent waste.

It does not stop at a number.

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12 in of runrise, inrafter linefootprintroof surfacefootprint x slope multiplier / 100 = squares
A roof is always bigger than the house under it, and how much bigger is right angle geometry rather than an allowance. Square the rise, add 144, take the root, divide by 12, and that multiplier turns a footprint into real surface area before any waste is added.

How that number is worked out

These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.

  • Building length36 ft
  • Building width48 ft
  • Roof pitch, rise per 12 in4 /12
  • Waste allowance10 %
  • Ridge length, 0 if unknown48 ft

Roofing squares needed20 squares

Footprint area1,728 sq ft
Slope multiplier at 4/121.05 x
Actual roof surface1,821 sq ft
Squares before waste18.2
Squares with 10% waste20order to this number

The material list this produces

Shingles, bundles (3 per square)61
Synthetic underlayment, rolls (10 sq each)3
Starter strip, linear ft180
Ridge cap, linear ft48
Drip edge, linear ft168
Roofing nails, lb44

Roof pitch compared

Pitch is the number most people guess at, and it is worth more shingles than any other input. Same house, five pitches.

Roof pitchRoofing squares needed
4/1220 squares
6/1221.3 squares
8/1222.8 squares
10/1224.7 squares
12/1226.9 squares

What else matters here

Seventeen hundred and twenty eight square feet of footprint at 4/12 is 1,821 square feet of roof, exactly twenty squares with waste, sixty one bundles.

Most buildings this size get an exposed fastener steel panel rather than shingles, and the reason is structural before it is economic. A pole barn is framed with purlins running across widely spaced trusses, and shingles need a solid deck under them, so shingling one means buying and installing sheathing that a metal panel does not need.

The trade is maintenance. An exposed fastener roof holds itself down with thousands of screws, each with a rubber washer, and those washers are the wear item. They need looking at every few years and a panel roof at twenty years often needs every screw replaced with a larger diameter one. Panels are ordered in the exact length of the run, so measure the slope length and the overhang before ordering rather than working from the footprint.

What this calculator assumes

  • Footprint times the slope multiplier gives the actual roof surface. A 6/12 roof is 11.8 percent larger than the ground it covers, which is the number most people forget.
  • Three bundles per square is standard for both three tab and architectural shingles. Check your brand, a few premium lines run four.
  • Synthetic underlayment is figured at 10 squares per roll, starter and ridge cap at one linear foot per foot.

Questions people ask

How many bundles of shingles for a 36x48 pole barn?

About 61 bundles at a 4/12 pitch with ten percent waste, which is 20 squares, plus the cost of sheathing the roof first.

Can you shingle a pole barn?

Yes, but it needs a solid deck over the purlins, which a steel panel does not. That sheathing is usually what makes shingles the more expensive option.

How long do exposed fastener metal roofs last?

The panels outlast the screws. The rubber washers are the wear item and often need replacing across the whole roof at around twenty years.

Different numbers?

The roofing calculator takes any dimensions you like and hands back the same list.

Other common sizes