There are three factors that make a steep roof more expensive to install:

1. More materials - The area of roofing of a 12/12 pitch roof (45º angle) over one square foot of floor area is 1.41 square feet. Another way to say the same thing is that a 12/12 pitch roof requires 41% more roofing material than a flat roof. As the slope of a roof gets cranked up higher and higher, the quantity of materials increases. Also, manufacturers may require additional fasteners for high slope roof. 
2. More labor - It’s not just the additional roof area that uses more labor, the work goes slower on a steep slope roof because of the difficulty moving around and requires an experienced roofing crew. 
3. Safety equipment - A roof above approximately an 8/12 pitch is no longer walkable without safety equipment, like roof jacks (brackets attached to the roof with walk boards) and safety harnesses with ropes secured to the ridge of the roof, as in the photo below. 

    Steep roofs offer advantages that help to offset the additional cost, however, like longer lifespan, better resistance to impact damage, improved attic ventilation, and less debris accumulation on the roof surface.

• • • • • • • • • • • • • • • • • • • • • • • • • • • •  

  To learn more about roofs and attics, see these other blog posts:

• Why is my roof sheathing sagging between the trusses?

• Why is granule loss a problem for an asphalt shingle roof? 

• What are the mistakes to avoid when doing attic improvements?

• What causes bubble-like blisters in a built-up and gravel roof?  

• Why does it cost so much more to replace a steep roof than a low slope roof? 

• What is "ponding" on a flat roof?

• Is an attic required to have a light by the building code? 

• How can I inspect my roof for hurricane damage?

• Why is there no attic access hatch in the house?

• What is the building code requirement for an attic access hatch, scuttle, or door? 

• Does a roof with multiple layers of shingles last longer?

• What can I do to prevent roof leaks?

• Are roof trusses better than roof rafters (stick framing)? 

• How can I make my roof last longer?  

• What are the warning signs of a dangerous attic pull-down ladder?

• How can I find out the age of a roof? 

• Should I buy a house that needs a new roof?

• Should I buy a house with an old roof? 

• What are those metal boxes on the roof?

• What does "lack of tab adhesion" in an asphalt shingle roof mean?

• Why do roof edges start leaking?

• Why do my dormer windows leak? 

• Do home inspectors go on the roof? Do they get in the attic?

• Should I put gutters on the house? 

• How much of a roof truss can I cut out to make a storage platform in the attic? 

• What's the difference between an "architectural" and a regular shingle roof? 

• What does a home inspector look for when examining a roof? 

• What are the hazards to avoid when going into an attic? 

     Visit our ROOF AND ATTIC page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.