Roofing your own house is one of the few major DIY projects that still saves serious money — typically $4,000 to $9,000 on an average 25-square asphalt shingle roof. It is also one of the most physically demanding and weather-dependent jobs you will ever take on. Learning how to roof properly means following a specific sequence, using the right fasteners, and respecting the manufacturer’s published install instructions because that is what your warranty hinges on.
Before You Start: Permits and Safety
Most US jurisdictions require a permit for a complete tear-off and re-roof. Check with your local building department — fees usually run $200-500 and an inspector wants to see the underlayment before shingles go on. Skipping the permit voids most homeowners insurance claims if a leak damages the home later.
Safety equipment is not optional. You need a roofing harness (Guardian Fall Protection HUV-2 or similar, $80-150), a 30-foot lifeline, a roof anchor screwed into a rafter, and a hard hat. Falls from residential roofs kill more DIYers than any other home project. Average residential roof pitch is 6/12 — steep enough that a slip means an emergency room visit.
Materials and Tools You Need
For a standard 25-square (2,500 square foot) asphalt re-roof, budget about $4,500 in materials and $300 in tool rentals. The shingle bundle math is straightforward: 3 bundles per square for architectural shingles like GAF Timberline HDZ or Owens Corning Duration.
- Shingles — 75 bundles GAF Timberline HDZ ($35-45/bundle) or Owens Corning Duration ($38-50/bundle)
- Synthetic underlayment — 5 rolls GAF Tiger Paw or Owens Corning Deck Defense ($90-130/roll, covers 10 squares)
- Ice and water shield — 4 rolls along eaves and valleys (Grace Ice & Water Shield, $90/roll for 200 sq ft)
- Drip edge — aluminum, 10-foot lengths, $9-12 each
- Roofing nails — 1-1/4 inch galvanized, 11-gauge, 7,500 nails per 25 squares
- Pneumatic roofing nailer — DeWalt DWFP12658 ($300-350) or rent from Home Depot at $55/day
- Roofing knife — Estwing or Stanley with hook blades
Step 1: Tear-Off
Rent a 20-yard dumpster for $400-550 and park it near a roof edge with the door open toward the house. Tear off shingles using a roofing shovel (Qual-Craft Shingle Eater, $40) starting at the ridge and working down. One person on the roof tossing into the dumpster, one person on the ground cleaning up overshoots.
Inspect every square foot of the decking once it is exposed. Replace any plywood that flexes more than 1/4 inch under your weight or shows water staining. Standard sheathing is 7/16-inch OSB or 1/2-inch plywood — match what is already there to keep nail penetration consistent.
Step 2: Drip Edge and Ice/Water Shield
Install drip edge along the eaves first, nailing every 12 inches with 1-1/4 inch roofing nails. Run ice and water shield over the drip edge, extending at least 24 inches up from the inside face of the exterior wall (most codes require 36 inches in cold-climate zones). Then install drip edge along the rakes, on top of the ice and water shield.
This order matters. Ice and water shield over the eave drip edge sheds water onto the gutter. Reverse it and meltwater can wick under the drip edge.
Step 3: Synthetic Underlayment
Roll out synthetic underlayment (GAF Tiger Paw or similar) starting at the eaves and overlapping each course by 4 inches. Use cap nails or plastic cap staples, not bare staples — bare staples pull through over time. Run the underlayment up and over the ridge by 6 inches on each side.
Synthetic underlayment beats traditional 30-pound felt on every spec that matters: lighter weight, higher tear strength, better walking traction, and UV exposure tolerance up to 90 days if rain delays the shingle install.
Step 4: Starter Course
Install a starter strip along the eaves. GAF Pro-Start or Owens Corning Starter Strip Plus both work — never use cut-down 3-tab shingles as a starter on architectural shingles. The factory-applied sealant on a real starter strip is positioned to glue down the first course at the eave edge. Without it, wind uplift will peel your first course in the first major storm.
Align the starter strip with the drip edge, leaving a 1/4-inch overhang. Nail per the manufacturer’s pattern — usually 4 nails per shingle, 1 inch from each end and roughly 12 inches apart in between.
Step 5: Field Shingles
Snap chalk lines every 5 inches to keep courses straight. Start the first field course directly over the starter, then offset each subsequent course by 6-1/2 inches (manufacturer-specific — check your bundle label). Nail with 4 nails per shingle for slopes under 60 degrees, 6 nails for steeper pitches or high-wind zones.
Nail placement is the most common warranty-voiding mistake. The nails must hit the manufacturer-printed nail line, which is usually a darker band about 5-1/2 inches up from the bottom edge on architectural shingles. Nails set too high miss the underlying course; nails set too low expose the head to weather.
Step 6: Valleys and Flashing
For valleys, run ice and water shield up the valley first, then install either a closed-cut valley (shingles run continuous across the valley) or an open valley with W-shaped valley metal. Closed-cut is more common on residential; open valley sheds debris better in heavy tree cover.
Step flashing protects sidewalls. Each piece of step flashing is bent at 90 degrees and tucks behind the siding, with one leg lying on the roof under the next shingle course. Counter-flashing or kickout flashing handles the bottom termination — kickout flashing alone prevents most siding rot at roof-wall intersections.
Step 7: Ridge Cap
Run the final shingle courses up to the ridge, trimming flush. Install ridge vent if specified (GAF Cobra Snow Country, Owens Corning VentSure) and cover with hip and ridge cap shingles like GAF Seal-A-Ridge. Nail each ridge cap with 2 nails per cap, exposing 5-5/8 inches.
The last cap at the end gets nailed down through both flaps with sealant under the head — the manufacturer pattern stops short of the final piece and that one needs extra attention.
What You Will Get Wrong on Your First Roof
Even careful DIYers learn how to roof properly the second time around. The most common first-time mistakes are nail height (set 90 PSI on the compressor, not 110), starter strip orientation (sealant band must face down at the eave), and underestimating dumpster size (rent the 20-yard, never the 15). Plan for two long weekends with a helper, finish in shoulder seasons (50-75 degree weather), and you will have a roof that performs for 25-30 years.
