Replacing Shingles on Low Sloped Roofs vs. Steep Sloped Roofs, Which Costs More?

There are many types of roof structures and the cost to install one depends much on the steepness or slope.

Roofers use the term “walkable” to describe a roof with a slope that isn’t too steep to safely walk on. The term is usually applied to roofs with a pitch of 8/12 or less. These roofs are sometimes referred to as “low-slope” roofs. Those with a steeper pitch are considered steep-sloped roofs. Most residential roofs range from 3/12 to 20/12 or steeper.

The first number in the pitch relates to the rise of the roof in inches. The second number is the run of the roof in inches. Twelve is always used for the run because it is one foot. So, a 6/12 roof rises toward the sky 6” for every horizontal (not sloped) foot it travels toward the center of the house.

How Does Roof Pitch Affect Roofing Prices?

For starters, the steeper the slope on a roof, the more shingles it will take to cover it. Asphalt shingle costs might be double on a 12/12 compared with a 4/12 roof. This is an important consideration if you’re building a new home. Talk to a building supply specialist about price quotes for asphalt shingle costs for different levels of pitch before you build.  It might be eye-opening. If you’re planning to replace shingles on an existing roof, there’s nothing cost-effective you can do to change the slope of the roof!

In terms of installing the shingles, your price quotes will be higher for any roof the contractor does not consider walkable. That may vary among roofing contractors, but generally it will be right about 8/12.

Why are costs higher?  There are a few key reasons. First, the steeper the slope in general, the more caution has to be used to ensure safety for the crew installing the roof. This will mean that the job will go slower. Roofers give their price quotes based on the estimated time it will take.

Secondly, if roof safety equipment such as rigging or scaffolding must be used, the written quotes you get will reflect that. The equipment is expensive to own or rent, and the price is passed along to the customer.

Thirdly, installing shingles on a steep-pitched roof requires different techniques. To keep the shingle warranty intact, the installer sometimes has to use more nails per shingle or apply roofing cement to each shingle. Either one will lead to an increase in both time and roofing materials, and hence higher price estimates.

Finally, some roofing contractors don’t have a crew with the skill and experience it takes to handle a steep roof. This limits the competition and leaves higher demand and higher margins of profit for the companies that can handle the job. There are many items that go into a roofing price quote and it is imperative to ask questions before you sign a contract.

Because of the additional materials, the increased time the job will take and the cost of equipment required to get the job done safely, replacing shingles on a steep-sloped roof will cost significantly more than doing the job on a low-sloped roof.

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