The do it yourself resource for homeowners from home improvement professionals.

How to Build a Roof

At P.J. Fitzpatrick, we encourage homeowners to leave the roof building to a professional who will take care of building codes, roofing materials, extra components, and more. In addition, they’ll make sure your roof is built properly so that it lasts for years to come. If you want to tackle roof building on your own, here’s a basic how-to. (Because there are so many roofing styles, shapes, and sizes out there, our experts share how to build a basic garage roof.)

Measured parts that include:

  • 6 2×4 Pieces of Lumber
  • A Top Ridge
  • 13 Bottom Rafters
  • 30 Rafters
  • 14 Pieces of Decking
  • 4 Pieces of Trim
  1. First, using your drill and screws, attach your bottom rafters to the top plates on the frame of your garage. (Remember to drill pilot holes first.)
  2. Before moving on, make sure you install two bottom rafters side-by-side at both ends of the roof for support.
  3. Next, attach two 2×4 pieces of lumber at either end of the frame to create a base for the top ridge. (Use your level to make sure they’re perfectly horizontal and plumb.)
  4. After that, install your ridge.
  5. Cut four 2×4 pieces of lumber and attach two at both ends of the roof to offer extra support for the end rafters.
  6. Continue by installing the rafters – attach them to both the bottom components and the top plates and leave around 24″ in between each rafter.
  7. Measure the front and back ends of the garage and use your circular saw to cut several pieces of plywood to fit the shapes. Then, attach the pieces to the structure.
  8. Next, attach your roof decking to your rafters. (Be sure to leave around 3/4″ overhang to cover the trims.)
  9. After that, attach your trims to the ends of your rafters.
  10. Cover your finished roof in roofing felt (overlapping the strips by at least 2″), then secure the tar paper with roofing staples and a staple gun. Don’t forget to cover the ridge and fit the side drip edges over the felt while fitting the bottom drip edges under the felt.
  11. Install your asphalt shingles and you’re done!

Tools & Materials

  • Safety Gloves, Goggles
  • Circular Saw
  • Chalk Line
  • Tape Measure
  • Level
  • Drill, Screws
  • Plywood
  • Felt Tar Paper
  • Staple Gun, Staples
  • Asphalt Shingles

Need help with this project?

We have trained professionals that can help. Contact us today. 1-877-246-4354

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