Squares, bundles, underlayment, ice barrier, drip edge, flashing, vents and nails for an asphalt shingle roof.
Answers
Sheet
Sheet A-1 · Roof
40′ × 25′ house, 6/12 roof
PRO STEP
Roof
1268
sq ft · 12.7 squares
Bundles
42
architectural, 10% waste
Pitch
6/12
27° · slope ×1.118
Tear-off
3,804 lb
1 layer · 10-yard dumpster
73–110 h of work
A pro crew: a day or two for most houses. Yourself: several weekends — open only what you can dry in each day.
Draft
The rules behind this Sheet are waiting for a licensed pro’s sign-off.
Most homeowners hire this out
Falls are the leading cause of death in construction (OSHA), and roofs are where many happen. Paid crews must be protected from falls from 6 ft up (OSHA). If you do it yourself: a harness tied to a roof anchor, roof brackets with a plank along the eaves, soft-soled shoes, a helper on the ground, dry and calm days only — and only open what you can dry in by evening.
Ice barrier: ask your building department
The IRC’s ice barrier (R905.1.2), in practice a peel-and-stick membrane, runs from the eaves to at least 24″ inside the exterior wall. Your town fills in whether it’s required (IRC Table R301.2(1)) — where ice dams happen, it usually is. We listed it as optional: ask, then answer “Ice barrier at the eaves” above.
Ask about a reroof permit
Towns differ: Minneapolis wants a permit for any reroof bigger than one bundle of shingles, and Des Moines needs none unless sheathing or rafters are repaired. Ask your local building department; structural repairs usually need one.
Drawing
Roof plan
1
Ridge 42 ft, ridge vent under the cap.
2
Eaves Drip edge, starter. 1′ overhang.
3
Rake Drip edge over the underlayment, starter.
4
Pipe boots 2 plumbing vents.
Seen from above, overhangs included. A plain rectangle: wings and dormers add valleys and walls.
What to buy
13 items · 2 if needed
Save to your jobs to check things off in the store.
Lumber
Roof sheathing, 7/16″ OSB 4×8
If needed
7/16″ 4×8
2 sheets
Keep the receipt — return it if you don’t use it.
Replaces soft or rotten deck found after the tear-off.
Fasteners
Plastic cap nails
2,000 a box
1 box
Nails with a wide plastic washer that hold underlayment without tearing it.
Roofing nails, coil
1¼″ galvanized, 7,200 a box
1 box
Galvanized roofing nails for a coil roofing nailer; long enough to go ¾″ into the deck or through it.
Ridge vent and cap
Roofing nails, coil · the length on the vent’s label
1 small box
Galvanized roofing nails for a coil roofing nailer; long enough to go ¾″ into the deck or through it.
Roofing
Architectural shingles (laminated)
3 bundles a square
42 bundles
Two-layer asphalt shingles; most cover a square (100 sq ft) with 3 bundles — read the wrapper.
Starter strip shingles
about 105 ft a bundle
2 bundles
The first course at the eaves and rakes: its sealant strip holds the edge of the first shingles down in wind.
Hip and ridge cap shingles
about 30 ft a bundle
2 bundles
Pre-bent caps for the ridge and hips; about 25–33 ft a bundle by brand.
Synthetic roof underlayment
10-square rolls
2 rolls
Woven, tear-resistant underlayment that replaced felt; 10-square rolls, fastened with cap nails.
Eaves, if required
If needed
Ice and water barrier (self-adhered) · 36″ × 66.7′ rolls
3 rolls
Keep the receipt — return it if you don’t use it.
Peel-and-stick membrane that seals around nails: the code’s ice barrier (US) or eave protection (Canada), and valley lining.
Drip edge
10′ pieces
18 pieces
Metal edge at the eaves and rakes that throws water clear of the fascia.
Pipe boot (vent flashing)
match each pipe size
2 boots
Flashing with a rubber collar for a plumbing vent pipe; match the pipe size.
Shingle-over ridge vent
4′ sections
10 sections
Vent along the ridge, covered with cap shingles; the label gives its net free area per foot.
Roofing sealant
10 oz tubes
3 tubes
Asphalt or polymer sealant for flashing edges, exposed nail heads and cap shingles — not a substitute for flashing.
Tools
You own 0 of 15 must-haves
Tap the ones you already own. That builds your Tool Shed as you go — no setup.
Must have
The job stalls without it.
Fall-protection kit
Harness, lanyard and a roof anchor screwed into a rafter — tie off before you step off the ladder
Extension ladder (24 ft)
Eaves about 10 ft up: a ladder 7–10 ft longer, tied off, 3 ft above the edge, 1 out for every 4 up
Shingle remover
Pries shingles and nails up together
Pry bar
Old flashing and stubborn nails
Heavy-duty tarps
Over plants, the AC unit and the driveway — and over open deck if rain comes
Utility knife + blades
Hook blades cut shingles from the back
Chalk line
Straight courses: snap a line every few courses
Tape measure (25 ft)
The red boxes every 16″ on the blade are stud spacing.
Aviation snips
Drip edge, valley metal and step flashing
Framing hammer
Nails, taps and persuades.
Caulk gun
Roofing sealant
Circular saw
Cuts the ridge vent slot and deck repairs
Magnetic nail sweeper
Run it over the yard and driveway twice — roofing nails find tires and feet
Safety glasses
Every cut, every nail, every time.
Work gloves
Tack strip, block and lumber shred hands.
Rent it
Costly to buy for one job. Rent it for a day.
Roll-off dumpster
≈3,804 lb of old roofing (12.7 squares × 1 layer × about 300 lb): a 10-yard roll-off — tell the hauler it’s shingles; most cap the weight
Rent
Coil roofing nailer
Or hand-nail with a roofing hatchet: about 264 nails a square
Rent
Air compressor + hose
Runs the roofing nailer
Rent
Nice to have
Faster or cleaner, not required.
Ladder stabilizer (standoff)
Holds the ladder off the gutter
Roof brackets (roof jacks)
With a 2× plank: a toe-hold at the eaves and a shelf for bundles, ≤ 8 ft apart, nailed into rafters
Knee pads
Flooring and tile are all knees.
Roof pitch gauge
Confirms the pitch before you order
Order of work
73–110 h of work
01
Before you start: order materials and the dumpster, check the forecast for dry, calm days, and cover plants, the AC unit and the driveway with tarps.
Check first
Forecast checked: enough dry, calm days, and tarps on hand if a storm pops up.
02
Set the ladder on firm ground, 1 out for every 4 up, tied off and 3 ft above the eaves. Harness on, roof anchor into a rafter near the ridge, before any other work.
Check first
Harness fitted, anchor screwed into a rafter (not just the deck), lanyard short enough to stop you before the edge.
03
Tear off one section at a time, only what you can dry in today: shingles, underlayment and nails, down to the deck.
Check first
Only open what you can dry in by evening.
04
Walk the deck: replace soft or rotten sheathing, drive or pull every nail, sweep it clean.
05
Drip edge along the eaves first, nailed every 12″ or less, pieces lapped 2″.
Check first
At the eaves the drip edge goes under the underlayment; at the rakes, over it.
06
Peel and stick: ice barrier along the eaves (if required), up to 3′ 5″ along the slope (2 courses).
07
Underlayment over the rest of the deck, from the eaves up, laps as printed on the roll, cap-nailed. Then drip edge along the rakes, over the underlayment.
08
Starter strip along the eaves and rakes, sealant strip at the edge, overhanging the drip edge as the wrapper shows.
09
Snap chalk lines and shingle from the eaves up: 4 nails a shingle in the nail line, offsets as the wrapper shows; set pipe boots as the courses reach them.
Check first
4 nails in every shingle, in the nail line, flush — not cocked or overdriven. Check the nailer depth on a scrap.
10
Cut the ridge slot as the vent’s label says, stopping 1 ft short of each end; nail the ridge vent.
Check first
Soffit vents open and unblocked by insulation: intake at least equal to the ridge vent.
11
Hip and ridge cap: hips from the bottom up, then the ridge, working away from the wind, with the longer nails through the vent.
12
Clean up: magnetic sweep the yard, beds and driveway twice, and haul the dumpster.
Mistakes that ruin the job
5 mistakes
1
High or crooked nails
Nails above or below the nail line, or overdriven, let shingles blow off and void the wind warranty. Set the nailer depth on a scrap first.
2
Opening more than you can dry in
A storm on bare deck soaks the ceilings below. Tear off only what you can cover by evening.
3
Old step flashing, no kick-out
Roof-to-wall leaks rot the wall behind the siding for years before they show. New step flashing at every course, a kick-out at the bottom.
4
More exhaust than intake
A ridge vent with blocked or missing soffit vents pulls air from the house instead of the eaves. Match the intake.
5
Working wet, frosty or windy
Wet underlayment is slick and cold shingles crack. Dry, calm days only — and never alone.