How to Install a Metal Ridge Cap and Hip Cap, With Closures and Venting
Closures, Z-flashing, cap laps and the ventilation slot that lets a metal roof breathe at the top.
- Advanced
- 3 to 6 hours for an average house
- Updated
The short answer
Finish the top of a metal roof by fitting profile closures or Z-closures above the last fasteners, then the ridge cap over them, lapped about 3 to 6 inches in the direction away from the prevailing wind, fastened through the panel rib or closure with sealant tape. Hips get a hip cap starting at the eave. On vented roofs leave a continuous slot with vented closures and mesh.
The ridge is where panels from both slopes meet and end. The cap has three jobs: it covers the gap between the panel ends, it keeps wind-driven rain and snow out of the open ribs, and, on a vented roof, it lets attic air escape. The closures under the cap do most of the sealing. The cap itself is the visible layer.
Hips are the same idea with an added complication. Panels meeting at a hip are cut at an angle and both ends need closures, and the cap has to run the length of the hip and finish at the ridge. Laying out the hip cap properly starts at the eave and ends where it meets the ridge cap.
Panel ends at the ridge are shaped before the cap goes on: see how to hem, fold and bend panel ends. The eave and rake details are in eave trim and rake trim.
Tools
- Aviation snips and offset snips
- Hand seamer
- Sheet metal brake for custom caps
- Impact driver
- Chalk line and tape measure
- Caulk gun
- Fall protection equipment
Materials
- Ridge cap and hip cap sections matched to the panel
- Foam profile closures or vented closures
- Z-closure or ridge flashing as the profile requires
- Trim screws with washers
- Butyl sealant tape
- Insect mesh or vent screen
- Touch-up paint
Safety first
- Working at the ridge means straddling the highest point on the roof. Tie off to a ridge anchor and never stand on the ridge cap itself, which dents and is slippery.
- Long caps catch wind. Fasten each section as it goes on.
- WorkSafeBC requires fall protection at 3 metres (about 10 feet) and wherever a fall of any height could cause serious injury.
Step by Step
Step 1: Decide on a vented or unvented ridge
A vented ridge leaves a slot at the ridge, commonly about 1 to 2 inches each side, so warm air escapes from the attic. The cap covers the slot and vented closures keep out rain, snow and insects. An unvented ridge uses solid closures and sits tight. The choice depends on the ventilation design, which also includes soffit intake; see attic ventilation basics and ridge vents.
Do not seal a ridge that the attic design needs open. A roof with soffit intake but a sealed ridge traps moist air, which leads to condensation and mould under the panels.
Step 2: Finish the panel tops and set the ridge gap
Panel ends at the ridge are usually turned up into an end dam, a small upturned lip, or hemmed, so wind-driven rain cannot run back under the panel. The dimension is in the manual, often about 1 inch. The gap between the two slopes at the ridge is also specified, commonly 1 to 2 inches for a vented ridge.
Cut panel tops square with shears, never an abrasive wheel, and keep the ends clean. See cutting metal roof panels.
Step 3: Fit the closures or Z-closure
A Z-closure is a bent metal strip that fastens along the top of the panels and creates a flat, continuous surface to carry the cap. It sits above the last fasteners and is sealed to the panel with butyl tape. Some profiles use foam closures that press into the ribs instead. Both should be sealed with butyl tape.
On vented roofs, use a vented closure with mesh, and leave the slot open. Closures should fit the rib profile tight, with no gaps at the ends, or wind-driven rain will get in.
Step 4: Install the first section of ridge cap and lap away from the wind
Place the first cap section centred on the ridge. Sections lap over each other, about 3 to 6 inches or as the manual says, with a bead of butyl tape between them. The overlap direction matters because wind pushes rain along the ridge. Wind direction at a ridge depends on the site, the terrain and the season, so check which way storms actually hit this roof, or ask the neighbours, before choosing the starting end.
Fasten through the cap into the closure or the panel ribs at the spacing in the manual, commonly 12 to 24 inches, with a screw at each lap. See metal roof screws for the washer compression.
Step 5: Start the hip cap at the eave and run up to the ridge
At a hip, panels from two planes meet at an angle. Cut them to the hip line, install closures or a hip flashing strip along the cut edges, and run the hip cap up from the eave end. Each section laps over the one below it. Start with a fold or end cap at the eave.
Where hips meet the ridge, cut the last hip cap to fit under the ridge cap or notch it into a saddle. This is the trickiest junction on the roof. Seal every joint and test-fit before fastening. See metal roof valleys for related panel cutting.
Step 6: Close the ends and seal the joints
Gable ends of the ridge cap are closed with an end cap, or the cap is folded down and tucked under the rake trim so wind and insects cannot get in. See rake trim.
Dab sealant over screw heads at the laps if the manual calls for it. Do not use sealant in place of a proper lap. Clean up shavings and touch up scratches on the cap.
Venting a Metal Ridge
A metal roof on a ventilated attic breathes through a balanced system: intake at the soffit and exhaust at the ridge. A typical ratio is about 1 square foot of net free vent area per 150 square feet of attic floor, split equally between intake and exhaust, although the building code and the ventilation guide give the number for your house. The ridge closure must have the net free area the design calls for, since some vented closures restrict more than others. See how to calculate attic ventilation.
Fraser Valley Notes
Wet winters and wind-driven rain, plus heavy snow at Hope, test the ridge. Vented closures need fine mesh and a baffle design that resists driven snow, and the cap laps should face away from storm wind. Needles and moss do collect at closures, so pick a design that can be cleaned.
Common Mistakes
- Sealing a ridge that the attic ventilation design needs open, which causes condensation under the panels.
- Lapping the cap into the wind, so driven rain goes straight into the joint.
- Using foam closures that do not match the panel profile, leaving gaps at the ribs.
- Skipping the end dam on the panels, which lets water run back under the closure.
- Fastening the cap through the roof surface instead of the closure line, leaving holes where water runs.
- Rushing the hip to ridge junction, which is the most common ridge leak.
- Standing on the cap, which dents it and breaks the seal.
When to Call a Professional
A simple gable ridge is manageable for a capable DIYer with fall protection. Hips, valleys meeting the ridge, vented ridge design and complicated intersections are best left to a roofer, because one wrong cut shows at the highest, most visible place on the roof.
If your attic has moisture, mould or frost, ask a roofer to check the ventilation design before finishing the ridge, since the cap detail depends on it.
Fraser Roofing does free roof inspections across the Fraser Valley, from Hope to Abbotsford. See our Metal Roofing service or the towns we cover.
How to Install a Metal Ridge and Hip Cap: Questions
How do you install a ridge cap on a metal roof?
Set profile closures or a Z-closure along the top of the panels, sealed with butyl tape, then lay the ridge cap over them. Lap sections about 3 to 6 inches with tape between, facing away from the prevailing wind. Fasten through the cap into the closure line at the manual's spacing and cap the ends at the gables.
What is a Z-closure on a metal roof?
A Z-closure is a bent metal strip, shaped like the letter Z, that fastens along the top of the panels at the ridge or at a wall. It supports the cap or flashing, and blocks the open ribs. It is sealed with butyl tape and fastened above the last panel fasteners, following the panel manufacturer's detail.
Do metal roofs need a ridge vent?
Not always, but many ventilated attics do. A vented ridge lets warm moist air escape, balanced with soffit intake, and reduces condensation under the panels. Whether you need one depends on the roof assembly, the ceiling air sealing and the code. Metal roofs commonly use vented closures with mesh under the ridge cap.
How far should ridge cap sections overlap on a metal roof?
Commonly 3 to 6 inches, with butyl sealant tape between the laps, and with the upwind section overlapping the downwind one. The exact overlap is in the trim manufacturer's installation manual. Fasten each lap with a screw and washer so the joint does not lift in wind.
How do you finish a hip on a metal roof?
Cut the panels on both planes to the hip line, fit closures or flashing strips along the cut edges, then run the hip cap from the eave up, each section lapping over the one below. The top of the hip cap is tucked under or notched into the ridge cap, and every joint is sealed.
Related Guides
All Metal Roofing guides|The full How-To Library
This guide is general education. Always follow the product manufacturer's installation instructions, the BC Building Code and WorkSafeBC requirements, which take priority over anything written here.
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