How to Roof a House: The Complete Process Explained

Understanding the Roofing Process

Whether you're hiring a professional or just want to understand what happens during a roof replacement, knowing the process helps you spot quality work (and cut corners). Here's every step of a proper residential roof installation.

Step 1: Tear-Off the Old Roof

The crew starts by removing everything down to the bare wood decking. This includes:

• All existing shingles and underlayment
• Old flashing around pipes, vents, chimneys, and walls
• Old ridge caps and drip edge
• Old valley flashing

Some contractors offer to overlay new shingles on top of old ones. We always recommend tear-off because it allows deck inspection and ensures the new roof's maximum lifespan.

Step 2: Inspect and Repair the Deck

With the old roof removed, the crew inspects every square foot of plywood decking. They're looking for:

• Rot: Soft, spongy, or discolored plywood gets replaced
• Delamination: Plywood layers separating means it's lost structural integrity
• Sagging: Decking that dips between rafters needs replacement or additional support
• Nail damage: Excessive nailing from previous roofs can weaken the deck

Damaged sections are cut out and replaced with new plywood. On a typical roof, expect 0-10 sheets of decking to need replacement. SquareDash includes a buffer for decking repair in every quote.

Step 3: Install Drip Edge

Metal drip edge is installed along the eaves (bottom edge) and rakes (side edges) of the roof. It serves two purposes: directing water away from the fascia board and providing a clean, finished edge for the shingles to hang over.

Step 4: Install Underlayment

Synthetic underlayment (like GAF FeltBuster or Owens Corning ProArmor) is rolled out over the entire roof deck. This waterproof barrier is your second line of defense if water gets under a shingle. Modern synthetic underlayment is stronger, lighter, and more tear-resistant than old felt paper.

In addition, ice and water shield (a self-adhesive waterproof membrane) is applied at:

• Eaves (first 3 feet from the edge) to prevent ice dam leaks
• Valleys where two roof planes meet
• Around all penetrations (pipes, vents, skylights)

Step 5: Install Flashing

Metal flashing is installed at every transition point to prevent water intrusion:

• Pipe boots: Rubber and metal boots around plumbing vents
• Chimney flashing: Step flashing and counter-flashing around the chimney
• Wall flashing: Step flashing where the roof meets vertical walls
• Valley flashing: Metal valleys (preferred) or woven shingle valleys

Step 6: Install Starter Shingles

Starter strip shingles are installed along the eaves and rakes. These specialized shingles have an adhesive strip that bonds to the first row of field shingles, providing wind resistance at the most vulnerable edge of the roof.

Step 7: Install Field Shingles

Working from bottom to top, the crew installs shingles in overlapping rows. Each shingle is fastened with 4-6 nails (depending on the nailing zone and wind requirements). Proper nailing placement is critical: nails placed too high or too low significantly reduce wind resistance.

Step 8: Install Ridge Vent and Cap

A slot is cut along the ridge (peak) of the roof for the ridge vent. The vent is installed, then covered with hip and ridge cap shingles that match the field shingles. This provides both ventilation and a finished look.

Step 9: Cleanup and Inspection

The crew does a thorough cleanup:

• All debris removed from roof, gutters, and ground
• Magnetic sweep of the yard, driveway, and surrounding area to catch stray nails
• Tarps removed, landscaping restored
• Final walkthrough to inspect the completed work

Ready for a New Roof?

Get your instant price from SquareDash. Every roof we install follows this exact process with certified crews and premium materials.