How to Install a Metal Roof: Step-by-Step Guide

So you're weighing the installation of a metal roof on your Kirkland or Bellevue home and want to know what the job actually involves before you call anyone or climb a ladder yourself. Metal roofing has become the top pick for Pacific Northwest homeowners who want something that shrugs off 50 inches of annual rain and doesn't need replacing every 15 to 20 years like asphalt shingles do.

This guide walks through the real metal roof installation process from start to finish, the same sequence our crews follow on jobs across Kirkland, Bothell, and Redmond. You'll get the prep work, the underlayment and flashing details that prevent leaks, panel layout, fastening technique, and the finishing touches that separate a roof that lasts 5 years from one that lasts 50.

We wrote this for homeowners seriously considering roof metal installation as a DIY project or who simply want to understand each step so they can evaluate a contractor's bid with confidence. Either way, you'll walk away knowing exactly what quality work looks like on your roof.

What to know before you start your metal roof project

Before you order a single panel, spend an afternoon on research. Skipping this step is how DIY roofers end up with leaks by year three or a red-tag notice from the building department. Kirkland and most King County jurisdictions require a permit for any roof replacement, metal or otherwise, and inspectors will check your underlayment, flashing, and fastening pattern before you close anything up. Check with the Washington State Department of Labor & Industries if you're pulling your own permit, since some panel systems also require a licensed contractor for warranty coverage.

Pick the right panel profile and gauge

Not all metal roofing is the same, and the panel you choose determines your fastening method, your tools, and your budget. Standing seam is the gold standard for Pacific Northwest homes because the concealed fasteners never puncture the panel face, which matters when you're fighting driving rain off the Sound.

Panel Type	Fastener Style	Typical Gauge	Lifespan	Best For
Standing seam	Concealed clips	24-26	40-70 years	Steep-pitch homes, high-rain areas
Corrugated	Exposed screws	26-29	20-30 years	Sheds, garages, budget jobs
R-panel	Exposed screws	26-29	20-35 years	Barns, low-visibility roofs

A roof that lasts 50 years starts with the right panel profile, not the cheapest one.

Gear up for a steep, slippery job

Metal roofing is genuinely dangerous work, more so than shingles because the surface stays slick even when it looks dry. You'll need a harness and anchor points rated for your weight, rubber-soled shoes with good grip, and roof jacks if your pitch is over 4:12. Gather these before installation day:

• Fall-arrest harness and rope grab

• Roof brackets or jacks for pitches above 4:12

• Seamer tool (for standing seam only)

• Cordless screw gun with depth-control clutch

• Tin snips and a panel-specific cutting tool

• Chalk line and speed square for layout

Understand also that metal expands and contracts with temperature swings, sometimes half an inch across a 40-foot run. Every fastener, clip, and seam detail in this guide accounts for that movement, and skipping it is the number one cause of buckled panels within the first two Northwest winters.

Step 1. Prepare the roof deck and underlayment

Strip the old roofing down to bare decking, then inspect every square foot for rot, soft spots, or delaminated plywood before you lay anything new. Metal roof installation only works long-term over a sound deck, so replace any sheathing that flexes under foot pressure or shows water staining, and re-nail loose panels to code spacing (6 inches on edges, 12 inches in the field).

Check and correct the deck

Walk the entire roof slowly, pressing down every few feet, and mark trouble spots with chalk before you start swapping sheathing. Fixing rot now costs a sheet of plywood and an hour. Ignoring it means a sagging roof deck three years from now that no amount of good metal panel work can hide.

Lay the right underlayment

Underlayment choice matters more on metal roofs than on shingle roofs, because metal transmits heat and cold straight through to the deck. Skip standard felt paper entirely. Use a high-temp synthetic underlayment rated for metal, and add self-adhered ice-and-water shield along eaves, valleys, and any low-slope transitions where Kirkland's winter freeze-thaw cycles push water backward under panels.

Skip the underlayment upgrade and you'll trade a leak-proof deck for a five-year warranty claim.

Run underlayment horizontally starting at the eave, overlapping each course by at least 4 inches, and fasten with cap nails every 12 inches. Seal all seams and any deck penetrations with compatible seam tape rather than caulk, since caulk degrades under UV exposure long before the metal panels above it do. This layer is your last line of defense if a seam ever opens up, so don't rush it.

Step 2. Install drip edge and trim

With underlayment down, turn to the metal trim pieces that frame every edge of the roof. Drip edge goes on first along the eaves, before your underlayment overlap at the bottom edge, and it directs water away from the fascia instead of letting it wick back under the deck. Skipping drip edge is a common shortcut on DIY jobs, and it's the reason so many homeowners find rotted fascia boards a few years into owning a metal roof installation they thought was done right.

Set eave and gable trim correctly

Fasten eave drip edge every 12 inches with corrosion-resistant nails or screws matched to your panel metal, aluminum with aluminum, steel with steel, to avoid galvanic corrosion where two dissimilar metals touch. Overlap each piece by 2 inches and run a bead of sealant tape under the overlap for a fully sealed edge. Gable trim comes next, running up the rake edges, and it should overlap the eave drip edge by at least an inch at every corner.

Mixing metals at the fasteners is a slow leak waiting to happen, match your hardware to your panels every time.

Prep valleys and penetrations before panels go on

Valley flashing needs to go down before a single roof panel touches the deck, since you can't tuck it underneath panels later. Use W-style valley metal with a raised center rib that keeps water from crossing over and backing up under the opposite slope.

• Center the valley metal precisely along the valley line

• Fasten only along the outer edges, never through the center channel

• Extend valley metal at least 12 inches past the eave for runoff

• Flag pipe boots, vent stacks, and skylight curbs now so trim work isn't rushed later

Get this trim layer right and everything you install afterward has a clean, sealed foundation to key into.

Step 3. Install and fasten the metal panels

Now the real work of metal roof installation begins. Start at one gable end and work across the roof, keeping every panel plumb with a chalk line rather than trusting the eave edge, which is rarely perfectly straight on older homes. Overhang the panel past the drip edge by three-quarters of an inch, and check your first panel twice before fastening anything, since every panel after it follows that same line.

Fasten with the right pattern and spacing

Fastening technique separates a roof that survives windstorms off Lake Washington from one that doesn't. For standing seam, drive concealed clips into the deck every 12 to 18 inches along the panel edge, spacing them tighter near eaves and ridges where wind uplift is strongest. For exposed-fastener panels like corrugated or R-panel, drive screws into the flat of the panel, never the rib, and snug them until the rubber washer compresses slightly without crushing.

A slightly loose screw today becomes a leaking screw hole in two winters.

Here's the fastener spacing we use on standard Kirkland-area jobs:

Location	Fastener Spacing	Notes
Field of roof	24 inches	Standard wind zone
Eaves and ridges	12 inches	High uplift areas
Panel overlaps	Every rib	Prevents wind lift at seams

Overlap panels and leave room to move

Overlap each panel by one full rib on the side and 6 inches on any end laps, running seams away from prevailing wind and rain direction. Leave clip-style fasteners slightly loose rather than cranked tight, since standing seam panels need to slide slightly as they expand and contract with temperature. Snap a control chalk line every few panels to catch drift early, because a half-inch error at panel ten becomes a six-inch problem by panel thirty.

Step 4. Finish with ridge cap and flashing

Once every panel is fastened and squared, the ridge cap ties both roof planes together and seals the single most vulnerable seam on the entire structure. Ridge details fail more often than any other part of a metal roof installation, mostly because homeowners rush the last few feet of a long project and skip the closure strips that keep wind-driven rain from tunneling underneath the cap.

Close the ridge before you cap it

Before setting the ridge cap, install foam closure strips shaped to match your panel profile along both sides of the ridge. These strips fill the wavy gaps under the ribs where insects, dust, and blowing rain would otherwise work their way into the attic space. Center the ridge cap over the peak so it overhangs both slopes evenly, then fasten through the high ribs only, using screws long enough to bite solid decking underneath.

A ridge cap without closure strips is an open invitation for wind-driven rain.

Flash every penetration and transition

Any place metal meets another surface, chimneys, skylights, sidewalls, plumbing vents, needs its own flashing detail rather than a bead of caulk. Use step flashing at sidewalls, woven under the siding and over the panel on each course, and set counter-flashing into the chimney mortar joint so water can't run behind it.

• Seal skylight curbs with manufacturer-matched flashing kits, not generic aluminum

• Wrap pipe boots with a storm collar for a second layer of protection

• Caulk only as a backup, never as the primary seal

• Re-check every flashing point after the first heavy rain

With flashing complete, walk the roof one last time and confirm every fastener is snug, every seam is lapped correctly, and no exposed metal edges are left unsealed. That final pass is what separates a roof that holds up through thirty Northwest winters from one that needs attention by year five.

When to call a roofing professional

Every step above is accurate, but that doesn't mean every homeowner should tackle it solo. Steep pitches, complex valleys, and multiple penetrations push a project from weekend DIY into professional territory fast, especially once you factor in fall risk and the cost of a botched seam that leaks into your attic insulation. Kirkland's permit inspectors have failed plenty of first-time installs on fastening pattern alone, and redoing panel work costs far more than hiring it out correctly the first time.

Getting the installation of a metal roof right takes the right tools, a steady crew, and years of reading how Northwest weather actually behaves against a roofline. If your project involves anything beyond a simple shed or garage, or you'd rather skip the ladder entirely, our crews handle standing seam and exposed-fastener systems across Kirkland, Bellevue, and Redmond every week. Request your free quote and inspection and we'll walk your roof with you before anything gets ordered.