How To Install a New Roof: It’s Simpler Than You Think Part I

A sound roof is critical to the health of your house. A worn roof can lead to leaks, ruined plaster or drywall—which, in turn, can cause rot in rafters, walls and ceilings, and even floors. Installing a new roof yourself can save at least half of the $2,000 to $6,000 it costs for a professional reroofing job of a typical 2,000 sq.ft. home. In this project, we’ll be using asphalt shingles since they account for 80% of all residential roofing. Let’s begin.

Safety Considerations
Safety First! Use eye protection when sawing, prying or performing other potentially hazardous aspects of the project. When using rolling scaffolding, remove everything from the platform when rolling it so that tools don’t fall off and harm someone. When using extension ladders, lay two bundles of shingles (about 60-lbs. each) against the ladder legs to keep the ladder from sliding out, and anchor the top of the ladder, too.

How To Install a New Roof: It's Simpler Than You Think Part I

Tools and Materials

  • Safety harnesses
  • Rolling scaffolding, which provides an inexpensive and convenient platform for lifting shingles up onto the roof and for working along perilous roof edges.
  • Extension ladders
  • Roof jacks and two 2×10 scaffolding boards 10-ft. long to lie across them to make narrow roof platforms. Set the jacks no more than 3 ft. apart by driving three 1 1/2-in. roofing nails through the shingles and roof sheathing into the rafters below. Place them under a shingle tab so that you can simply tap the jack loose and drive the nails down when finished.
  • Tarps and sheets of plywood (for easier cleanup)
  • Large trash container (about $350 to rent)
  • Galvanized roofing nails (with extra large heads)
  • Metal drip edge
  • 2x4s, plywood and wood sheathing
  • 2×4 cleats
  • 25-year shingles, which provide exceptional value, quality look and durability
  • Circular saw (to cut out rotted sheathing) and shovel (to pry off old layers of shingles)
  • No. 5 asphalt-impregnated felt
  • Valley and eave flashing (No. 30 felt or heavier)
  • Underlayment (No. 15 felt)
  • Utility knife and “hook blade” utility knife
  • Straightedge and 2-inch putty knife
  • Plastic roofing cement (the number of 1-gal. cans necessary for your job)
  • Measuring tape and chalk
  • Metal flashings (26-gauge galvanized steel or aluminum; both come in 10-in. rolls)
  • Silicone caulk
  • Wide sheet metal (to create cap flashing)
  • Mortar, mortar board and 3/8-in. “pointing” trowel
  • Preformed metal and rubber pipe flashing
  • Roof vents (if current ones rusted or worn)

Installing the New Roof: Step by Step
1. Begin the tear-off from above (at the ridge) and work down the roof using a shovel to pry off old layers of shingles as you go. Protect your bushes, windows and the sides of the house below with tarps and sheets of plywood to avoid damage from falling shingles. In most cases it’s better to remove the old metal flashings along with the shingles. Tear off no more than half of your roofing at a time before you reshingle (since temporary coverings never work as well in the rain as the old roof). caution: Roof sheathing is more slippery than the shingle surface, so tread carefully, especially around roof edges. After prying off the shingles, nail 2×4 cleats to the sheathing to make walking easier (with roof jacks and scaffolding boards mounted near the bottom in case you slip).

2. Work over the entire roof surface once the shingles and old metal flashing are removed. Pull out all old roofing nails, renailing loose roof boards and replacing rotten ones. Use a circular saw to cut out the rotted sheathing. Make vertical cuts over the exact center of rafters so you can nail in a new piece of sheathing.

Flashing Part 1: Installation and Underlayment
3. Lay eave flashing and a metal drip edge along the lower roof edge. Poor flashing is a primary reason for roof leaks. As a rule, nail flashings and shingles using galvanized roofing nails (they have extra-large heads) long enough to penetrate the roof sheathing at least 3/4 in. The drip edge is an L-shaped metal strip that’s nailed to the lower edge of the roof to keep water from seeping back into the roof sheathing. If possible, lap it over the gutter for better drainage. Eave flashing is required in all “severe weather” regions. (When you obtain your building permit, ask your local building inspector for the specific flashing and shingling requirements for your region.) Use either a heavy asphalt sheet (No. 40 or heavier) that comes in rolls, or a sticky rubber membrane called “ice and water barrier” that bonds directly to the wood sheathing.

Nail the underlayment, which is No. 15 asphalt-impregnated felt paper, over all of the remaining exposed wood sheathing. Nail a metal drip edge over the No. 15 felt underlayment at the roof rake, which is the edge of the roof that slopes upward. While optional in some situations, this flashing is essential if you have aluminum or vinyl trim.

Now you’re ready to shingle. (We’ll introduce other types of flashing later.)

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