How to Install Ridge Cap Shingles: Tools, Nailing Pattern, and 7 Common Mistakes

By The Roofing Brief Team. Last reviewed: October 2026.

How to install ridge cap shingles, in order: snap a chalk line just under half the cap width off the peak on both sides (6 inches for a 12-inch cap), start at the end of the ridge opposite the prevailing wind, fasten each piece with two nails 1 inch in from each edge at the height the wrapper prints (6 1/4 inches above the butt edge on IKO Hip & Ridge 12), expose each piece by the maker’s figure (5 5/8 inches on IKO Hip & Ridge 12, 8 inches on CertainTeed Cedar Crest), and cover the exposed nail heads of the final cap with roofing cement. On a roof with a ridge vent, the vent goes down first and the caps nail through it per the vent maker’s sheet. Those five numbers (line offset, start end, nail height, exposure, sealed last cap) decide whether the ridge of a roof installation sheds wind-driven rain or leaks.

Ridge cap decision table: which rule applies to your roof

If your roof has…	Then do this	Rule or source
A gable ridge	Start at the end opposite the prevailing wind and run to the other end	IKO Hip & Ridge 12 instructions, Step 4
Hips plus a ridge	Cap each hip from the eave end up to the ridge, then cap the ridge from each end so the runs meet in the middle	IKO Hip & Ridge 12 instructions, Step 4
Deck under 3/4 inch thick (7/16 OSB, 1/2 plywood)	Nail must exit the underside of the deck by at least 1/8 inch	IKO fastener note; IRC R905.2.5 (through the sheathing)
Deck 3/4 inch or thicker (1-inch plank)	Nail must reach at least 3/4 inch into the deck after passing through the cap and field layers	IRC R905.2.5
Cap exposure 8 inches or more (Cedar Crest, UltraHP)	Nail higher than on a 5 5/8 inch cap: 8 5/8 inches above the butt on Cedar Crest	CertainTeed and IKO instructions
Cold weather (caps stiff when bent)	Store bundles in a heated space before bending	IKO Hip & Ridge 12 instructions, Step 5
A ridge vent	Install the vent first, then nail caps through it with the longer nails the vent maker lists	Vent maker’s instructions
Work 6 feet or more above a lower level (every ridge)	Paid crews must use guardrails, nets or personal fall arrest; DIYers should rig a harness and anchor	OSHA 29 CFR 1926.501(b)(13)

The short answer: what ridge cap is doing

Ridge cap is the line of bent shingles running along the peak of the roof. Installing it, also called capping a roof ridge or shingling the peak, is the last course on a shingle roof and covers the joint where the top courses of the two roof planes meet. On hip roofs, the same product runs down each hip. On gable roofs, it only runs the main ridge. Every piece carries a self-seal strip that has to bond to the piece below; on IKO Hip & Ridge 12 the nails sit just below the factory sealant buttons, per IKO’s Step 3. Skip the manufacturer cap product, nail below the maker’s line, or run the caps the wrong direction, and the ridge is the first part of the roof to lift.

Tools and materials

Item	Spec	Why it matters
Ridge cap shingles	Manufacturer-matched (GAF Seal-A-Ridge, OC ProEdge, CertainTeed Cedar Crest, IKO Hip & Ridge)	Pre-formed, color-matched, warranty-compliant
Roofing nails	11 or 12 gauge, corrosion-resistant, 3/8-inch minimum head; 2-inch length on most caps (IKO), longer over plank decks or vents	IRC R905.2.5: 3/4 inch into the deck or through it
Chalk line	Blue or red chalk	Black chalk is permanent and shows through translucent shingles in time
Utility knife	Hook blade preferred	Cleaner cuts on the starter cap and end pieces
Roof cement	ASTM D4586, plastic tube	Hand-seal the final cap and any exposed nails
Caulk gun	Standard	Roof cement application
Hammer or coil nailer	21-degree coil nailer with depth control	Hand-nailing preferred on ridge for nail placement accuracy
Tape measure, pencil	Standard	Marking exposure on the first few caps to set the rhythm

Bundle coverage is printed on the wrapper and differs by brand: GAF Seal-A-Ridge is sold as 25 linear feet per bundle, Owens Corning ProEdge as 33 linear feet, and IKO Hip & Ridge 12 as 33.3 to 36.5 linear feet depending on the supplier’s listing (Home Depot, Lowe’s and roofing supply listings, October 2026). Add 10% for waste and overlaps. Our bundle math guide shows how to turn ridge and hip length into a bundle count.

Determine wind direction first

The single rule that homeowners and weekend installers get wrong: ridge cap is directional. Each cap laps over the one before it, and the exposed butt edges must face away from the prevailing wind. The IKO Hip & Ridge 12 instructions put it as starting the ridge “at the end opposite to the prevailing wind direction”. Install the caps the other direction and every gust hits the open butt edge, lifts it, and drives water under the lap.

Check a wind rose for the nearest airport station on the Iowa Environmental Mesonet wind rose tool, which plots years of ASOS airport observations by direction and speed. If the dominant spokes point west or southwest, start the ridge at the east or northeast end and work toward the wind. On hip roofs the rule changes: IKO says to cap each hip from the lower end up, then run the ridge from each end so the two runs meet in the middle.

This is the same logic as field shingles: the next course covers the nails of the course below it. Get the direction wrong on a 40-foot ridge and the butt edges of all 70 or so pieces (at a 6 2/3 inch exposure) face straight into the next storm.

Step 1: snap chalk lines for alignment

Measure 6 inches down from the ridge on each side and snap a chalk line the full length of the ridge. The caps will straddle the ridge with their bottom edges falling on these lines. A 12-inch wide pre-formed cap centered on the ridge gives 6 inches on each side, which lands exactly on the chalk.

The chalk line matters because a cap that drifts 1/2 inch off the line over a 30-foot run is visible from the street, and a cap pulled too far to one side leaves less than the maker’s coverage on the other slope. IKO’s blog tells installers to snap the line a little less than half the cap width from the peak so the cap edge, not its center, follows the line.

Step 2: starter cap at the downwind end

The first cap is special. Cut a single cap shingle so that only the exposed portion (the 5 to 6 inch piece that will show) remains. Place this trimmed piece at the very start of the ridge with the cut edge flush with the rake or hip corner. Nail it with four nails: two on each side, set 1 inch in from the edge and 1 inch up from the chalk line.

The full-length first cap then goes directly on top of the starter, fully covering it, so the first butt edge at the rake has two layers and a sealant bond under it instead of bare field shingles. On hips, the IKO Hip & Ridge 12 instructions add one more rule: trim the first piece at the eave so its corners do not hang past the shingle edge into the gutter line.

Step 3: nailing the field caps

Each cap after the starter gets two nails. The nails go 1 inch in from each side, at the maker’s nail line above the butt edge, so that the next cap covers them. On IKO Hip & Ridge 12 that line is 6 1/4 inches above the butt edge with a 5 5/8 inch exposure, per IKO’s Step 3, which leaves 5/8 inch of the next piece covering the nail heads.

Critical: read the wrapper. Some brands (GAF Seal-A-Ridge, IKO Hip & Ridge) print nail placement marks directly on the cap. Use those if present. Longer caps nail higher. CertainTeed’s Cedar Crest instructions, for example, call for an 8 inch exposure with nails 8 5/8 inches up from the exposed butt edge, and Owens Corning specifies ProEdge nails 7 1/4 inches from the exposed end.

Nail height by product: the 5/8-inch cover rule

The nail line on each product sits about 5/8 inch above the exposure line: IKO Hip & Ridge 12 nails at 6 1/4 inches with a 5 5/8 inch exposure, and CertainTeed Cedar Crest nails at 8 5/8 inches with an 8 inch exposure. That 5/8 inch is what keeps the nail head under the next cap. Nail at the exposure line itself and the head sits right at the butt edge of the next piece, one storm away from exposure.

Cap product	Exposure	Nail height above butt edge	Nails per piece	Source
IKO Hip & Ridge 12	5 5/8 in	6 1/4 in, 1 in from each edge	2	IKO Hip & Ridge 12 application instructions (04/20)
IKO UltraHP / UltraHP IR	8 1/2 in	Higher than standard caps, per wrapper	2	IKO hip and ridge guide
GAF Seal-A-Ridge	6 2/3 in (5 in on 60-cap bundle)	Per printed nail marks	2	GAF data sheet
CertainTeed Cedar Crest	8 in	8 5/8 in	2	CertainTeed application instructions
Owens Corning ProEdge	Per current OC sheet	7 1/4 in from the exposed end	2	Owens Corning installation instructions

What goes wrong if you nail too low

If the nails go below the maker’s line (6 1/4 inches above the butt on IKO Hip & Ridge 12), they end up in the exposed portion of the cap. Every nail head becomes a potential leak point. UV degrades the gasket seal, the head rusts, and water tracks down the shank into the deck. This is the single most common ridge cap failure mode an inspector flags.

What goes wrong if you nail too high

If the nails go well above the maker’s line, they end up close to the bend and outside the zone the sealant strip of the next piece holds down. On a cold day the cap can crack at the bend during nailing, especially with the thicker asphalt of premium caps such as IKO UltraHP; IKO’s fix is to store bundles in a heated area before cold-weather application.

Step 4: exposure and overlap rhythm

Many pre-formed ridge caps are installed at a 5 5/8 to 6 2/3 inch exposure, but follow the wrapper: CertainTeed Cedar Crest calls for 8 inches and IKO UltraHP 8 1/2 inches. Measure from the leading edge of one cap to the leading edge of the next. The covered portion (overlap) is whatever the cap length minus the exposure works out to: typically 6 to 7 inches.

Mark the exposure on the first three caps with a pencil tick. A 1/8 inch creep per piece adds up to almost 9 inches over 70 pieces on a 40-foot ridge, which throws off the last cap and the piece count. Measure every 10th cap against a tape after the rhythm sets.

If you’re installing pre-formed caps on top of an active ridge vent (a slot cut in the sheathing for attic ventilation), check the vent product spec. Some require a specific cap pattern. Most ridge vents (GAF Cobra, OC VentSure, CertainTeed Ridge Vent) ship with their own integrated installation instructions for cap nailing through the vent product. See our attic ventilation guide for ridge vent context.

Step 5: the final cap and sealing

The last cap on the run cannot be overlapped, so its nails are exposed to weather. Two options to handle this:

• Hand-seal the nails. Drive two nails as normal, then cover each nail head with a quarter-sized dollop of roof cement (ASTM D4586). This is the standard method, and it matches IKO’s Step 5: “Cover the exposed nail heads of the final shingle with roofing cement.”
• Pre-cement the cap underside. Apply a bead of roof cement to the underside of the cap before placing it, nail it down, then cover the heads with cement. The IKO Roofing blog describes setting the final shingle in cement; it is the belt-and-suspenders option for coastal and high-wind ridges.

Either way, the final cap is the last line of defense and the most likely future leak point. Don’t rush it.

Hip ridges vs main ridges

The technique is identical on hip ridges, with two adjustments. First, hips meet at the peak in a three-way intersection. The last cap on each hip is trimmed at an angle to meet the others, and the intersection itself is sealed with roof cement under each trimmed end. Second, hips run from the eave up, per IKO Hip & Ridge 12 Step 4, so the butt edges face downslope and the ridge caps then lap over the top piece of each hip.

The peak intersection where three or four hips meet is a leak-prone detail. The conservative pro method is to install a manufacturer-specified hip-peak cap or a custom-cut 12 by 12 inch shingle patch over the intersection, bedded in roof cement, with nails covered.

Cut-up 3-tab caps: when (and why not) to use them

Before pre-formed caps existed, roofers cut 3-tab field shingles into three 12-inch pieces and bent each piece over the ridge as a cap. The technique still works mechanically on a 3-tab roof, but it has three problems in 2026:

• Warranty risk. Each maker’s installation instructions call for its own hip and ridge shingles: GAF Ridge Cap Shingles, an Owens Corning Hip & Ridge shingle, CertainTeed Shadow Ridge, Cedar Crest or Mountain Ridge, and IKO’s recommended pre-cut Hip and Ridge products. GAF’s Shingle & Accessory Limited Warranty (RESWT160L) is conditioned on installing per GAF’s application instructions, and its ridge cap wind coverage applies only to GAF Ridge Cap Shingles. Upgraded coverage spells the cap out: GAF’s WindProven wind warranty requires GAF ridge cap shingles among other accessories, and CertainTeed’s 160 mph Landmark wind upgrade requires CertainTeed starter and hip and ridge. How cut-up 3-tabs affect your coverage depends on the specific warranty, so read it before you buy.
• Color mismatch. A single-layer 3-tab cannot copy the two-layer shadow blend of a laminated shingle, even when the color names match.
• Cold weather cracking. Asphalt shingles stiffen in the cold, and a field shingle bent over a ridge can crack. The CertainTeed Landmark instructions say shingles must be warm enough to form properly at hips and ridges, and IKO’s Cambridge instructions say to store hip and ridge shingles in a heated area before cold-weather application so they bend more easily.

Cut-up 3-tabs still appear on budget reroofs and storage sheds. For an owner-occupied home with laminated shingles, the maker’s pre-formed cap (about $64 to $85 per bundle in October 2026 listings) costs little more than the 3-tab bundles it replaces. See our ridge cap shingles guide for the product comparison.

Common ridge cap mistakes

1. Running caps the wrong direction

Wind lifts the open butt edge of every cap, water tracks under the lap, and the ridge fails in the first big storm. IKO Hip & Ridge 12 Step 4 sets the rule (start opposite the prevailing wind), and the error is the easiest to spot from the ground because the butt edges face the wrong way.

2. Nails in the exposed area

Nail head visible in the bottom 5 to 6 inches of any cap is a leak waiting to happen. Cover with roof cement immediately if you spot it on an existing roof.

3. Mixing 3-tab field with architectural caps (or vice versa)

The exposure math is different: a cut 3-tab piece shows about 5 to 5 5/8 inches, while caps made for laminated roofs run 6 2/3 inches (Seal-A-Ridge) to 8 1/2 inches (UltraHP). A 3-tab cap on an architectural ridge looks thin, and a thick cap on a 3-tab field looks heavy.

4. Skipping the starter cap

Without the doubled-up starter at the downwind end, the first cap’s butt edge sits on bare field shingles with no sealant strip under it and is the first piece the wind reaches. Check the wrapper for the maker’s first-piece detail; the IKO Hip & Ridge 12 instructions, for example, call for trimming the first piece at the eave.

5. No sealant on the final cap

Exposed nails at the end of the run are the only exposed fasteners on a correctly shingled roof. Leave them bare and the leak tends to show up in the attic years later, so cover every head, as Step 5 of the IKO Hip & Ridge 12 sheet requires.

6. Wrong nail length on plank decks

IRC R905.2.5 requires roofing nails to reach 3/4 inch into the sheathing or go through it, and IKO’s fastener note adds that on decks thinner than 3/4 inch the point must exit by at least 1/8 inch. Add the thickness of the cap and field layers at the ridge to the deck thickness (7/16 to 1/2 inch OSB or plywood, or 1-inch plank on older homes) and pick a nail that clears it; IKO’s minimum for ridge caps is 2 inches. Shorter nails back out under thermal cycling.

7. Cap installed over an unflashed ridge vent slot

If a ridge vent is being installed, the vent product goes down first, then the caps go over the vent per the vent manufacturer’s spec. Caps installed directly over a raw vent slot leak immediately. On a GAF Cobra or OC VentSure vent, the caps nail through the vent with the longer nails that vent’s instructions list. See our attic ventilation guide for ridge vent install sequencing.

Pre-formed ridge cap product comparison

Product	Length	Exposure	Wind warranty	Typical pairing
GAF Seal-A-Ridge	About 12 inches wide	6 2/3 inches (5 inches on the 60-cap bundle), per GAF’s data sheet	110 mph (LayerLock cert) or 130 mph (system)	GAF Timberline HDZ
Owens Corning ProEdge	12 inches	Per current OC instructions (nails 7 1/4 inches from the exposed end)	110 mph standard, 130 mph SureNail system	OC Duration, Oakridge
CertainTeed Cedar Crest	12 inches	8 inches, per CertainTeed’s application instructions	110 mph, 15-year wind warranty	CT Landmark, Presidential
IKO Hip & Ridge 12	12 inches	5 5/8 inches, per IKO’s application instructions	110 mph	IKO Dynasty, Cambridge

Buy the cap that matches the field shingle manufacturer. Enhanced system warranties count only the maker’s own qualifying accessories (GAF’s Roofing System warranty, for example, requires a GAF Lifetime shingle plus at least three qualifying GAF accessories), so a cap from another brand will not help the roof qualify for that coverage. CertainTeed’s Cedar Crest page lists that cap with a 15-year 110 mph wind warranty and a UL 2218 Class 4 impact rating.

Cost to install ridge cap

Material is the only cost a DIYer controls. These are October 2026 retailer and supplier listings for one bundle; check your local store, since color and region move the price.

Cap product	Linear feet per bundle	Price per bundle	Cost per linear foot	Source
GAF Seal-A-Ridge	25	$63.97 to $67.98	About $2.56 to $2.72	Home Depot and Lowe’s listings, Oct 2026
Owens Corning ProEdge	33	$67.98 to $82.99	About $2.06 to $2.51	Lowe’s, Home Depot and S.W. Collins listings, Oct 2026
IKO Hip & Ridge 12	33.3 to 36.5	$75.81 to $84.59	About $2.28 to $2.32	Doug Ashy and Ring’s End listings, Oct 2026

Worked example: a gable ridge of 50 linear feet in GAF Seal-A-Ridge needs 50 x 1.10 waste = 55 linear feet, or 55 / 25 = 2.2, rounded up to 3 bundles. At $63.97 that is $191.91 in caps, plus about 180 two-inch nails (two per piece for roughly 90 pieces at a 6 2/3 inch exposure) and one tube of roof cement for the end cap.

On a reroof, ridge cap is rarely priced as a line item. Verify the contract specifies the maker’s pre-formed cap by product name (for example “GAF Seal-A-Ridge” or “IKO Hip & Ridge 12”), not just “ridge cap.” Cut-up 3-tab billed as ridge cap is a cost-cutting substitution worth checking for on completion day.

When to call a pro

Ridge cap is one of the shorter DIY roofing tasks (a 40-foot ridge is about 70 pieces at a 6 2/3 inch exposure), but every piece is set at the highest point of the roof, more than 6 feet above the eave, the height at which OSHA 1926.501(b)(13) requires fall protection for paid crews. The reasons to bring in a pro anyway:

• Steep slopes above 8:12. The peak is high, the fall distance is long, and harness setup is mandatory. See our roof safety guide.
• Ridge vent retrofit. Cutting the slot is structural and the integrated install is best handled by a roofer.
• Leak diagnosis. A leak that predates the ridge work may start at a chimney, vent boot or valley; see how to fix a roof leak.
• Architectural or designer shingle warranty work. The top warranty tiers, such as GAF’s Golden Pledge, are only available through the maker’s certified contractors.

Frequently asked questions

What direction do I run the ridge caps?

Start at the downwind end and run toward the prevailing wind, so the open butt edges face away from it. IKO’s Hip and Ridge 12 instructions say to start gable ridges at the end opposite the prevailing wind, run hips from the lower end up, and on hip roofs run the ridge from each end to meet in the middle. Check a local wind rose for your nearest airport before you start.

Where on the roof should there be surface-exposed nails?

Only at the single last ridge cap (and the last cap where hip runs meet), because nothing overlaps it. Every other nail on a shingle roof is covered by the next course. The IKO Hip and Ridge 12 instructions say to cover the exposed nail heads of the final shingle with roofing cement.

Can I use my leftover field shingles as ridge caps?

Only on 3-tab field shingle installs (and even then it’s becoming uncommon). On architectural shingle installs, the makers’ installation instructions call for their own hip and ridge product (GAF Seal-A-Ridge, OC ProEdge, CertainTeed Cedar Crest, IKO Hip & Ridge), and upgraded coverage such as GAF’s WindProven wind warranty requires the maker’s ridge cap. Cut-up laminated field shingles are not a method those instructions provide for, so check your warranty before trying it.

Which shingles are used to make ridge caps?

Traditionally, three-tab shingles cut into three 12-inch pieces. Laminated (architectural) shingles are too thick to cut and bend, so makers sell pre-formed or perforated cap shingles such as GAF Seal-A-Ridge and IKO Hip and Ridge 12, which separates into thirds at the perforations.

How many nails per ridge cap?

Two nails per cap, 1 inch in from each side, at the height the maker prints: 6 1/4 inches above the butt edge on IKO Hip and Ridge 12 and 8 5/8 inches on CertainTeed Cedar Crest. The next cap covers those nails. The doubled-up starter gets four nails, and the very last cap gets two nails plus roofing cement over each head.

What’s the exposure for ridge cap shingles?

Exposure depends on the product, so read the wrapper. Per the manufacturers’ data sheets and application instructions, GAF Seal-A-Ridge is 6 2/3 inches (5 inches on its 60-cap bundle), CertainTeed Cedar Crest is 8 inches, IKO Hip and Ridge 12 is 5 5/8 inches and IKO UltraHP is 8 1/2 inches. Owens Corning now specifies ProEdge nails 7 1/4 inches from the exposed end, so check its current instructions for exposure. Mark the first three caps with a pencil to set the rhythm.

Do I need ice and water shield under the ridge cap?

Not typically required, but recommended in heavy snow climates and on any ridge that has had a leak history. A 12-inch wide strip of ice and water shield centered on the ridge, installed before the caps, adds a second water barrier where the field shingles meet. Ridge vent installs handle this differently per the vent manufacturer.

Bottom line

Ridge cap is one of those details where the difference between a good install and a bad install can stay hidden for years, then show up as a ridge-line leak that stains the attic and rots the top course of decking. The work itself comes down to four checkable items: the maker’s pre-formed cap, a start opposite the prevailing wind, two nails 1 inch in at the printed nail line, and a cemented final cap.

If you’re DIY, mark the first three exposures, measure every 10th cap and keep 2-inch nails on the ridge. If you’re hiring out, write the cap product name (for example “IKO Hip & Ridge 12” or “GAF Seal-A-Ridge”) into the contract and check on completion day that the butt edges face away from the prevailing wind.