How to Install Metal Roofing

Staff Desk
1 hour ago
14 min read

(Step-by-step guide based on a real 28×60 roof install)

Metal roofing has a reputation for being expensive and tricky to work with. It can be both of those things, but it does not have to be. With screw-down metal panels, basic carpentry skills, and the right sequence, it is possible to install a durable metal roof at a relatively low cost.

This blog walks through the entire process, from structure prep right through to ridge caps and vent pipes, using the workflow from a 28×60 building with a 4½/12 pitch and 1 ft overhangs.

1. Standing Seam vs Screw-Down: Choosing the System

Before anything goes on the roof, it helps to be clear about the two main styles of metal roofing.

Standing seam metal

Pros

No exposed fasteners
Much lower risk of leaks long term
Very clean, modern appearance

Cons

Roughly double the cost of screw-down metal
More complex installation
More time consuming
Typically needs specialized tools and familiarity

Screw-down (exposed fastener) metal

This is the system used in the build from the transcript.

Pros

About half the cost of standing seam
Simple installation with standard tools
Much faster to install

Cons

Fasteners are exposed to the weather
Washers and screws will eventually need maintenance
Slightly higher risk of leaks over the life of the roof

For most budget-conscious projects, screw-down panels are the practical choice, especially for garages, sheds, and many houses where cost and speed matter.

2. Tools, Materials, and Safety

Key materials

2×4s for purlins (installed perpendicular to rafters or trusses)
2×6 subfascia at eaves
29-gauge screw-down metal roofing panels (36" coverage, 9" rib spacing in the example)
Drip edge trim
Rake edge trim
Gable trim (sometimes called gable or corner trim)
Fascia metal
Foam board underlayment with foil face (for sound deadening and vapor barrier)
Inside foam closures for panel bottoms
Outside or vented closures for ridge
Ridge cap sections
Pipe boot flashing for vent pipes
Color-matched roofing sealant
1½" metal roofing screws with neoprene washers and metal caps
2" metal roofing screws for ridge cap (to go through ribs and into framing)
Roofing nails or screws for attaching trim and foam

Core tools

Circular saw (for framing and for scoring foam boards)
Speed square / framing square
Tape measure
Tin snips (left, right, and straight are useful)
Impact driver with 5/16" hex bit for roofing screws
Drill and drill bits
Hole cutter for metal (e.g. Malco HC1 style circle cutter)
Chalk line
Utility knife
Needle nose pliers (for fine adjustments and tightening hole cutter pivots)

Safety equipment

Working on a roof is inherently risky. Proper safety habits are non-negotiable.

Roof harness and lanyard
Roof anchor brackets and suitable screws/lag bolts
Non-slip shoes with clean soles
Stable, properly tied off extension ladder

Never work on a roof when uncomfortable or unsure. Wet or icy metal is especially dangerous, so always dry it off before walking, and avoid poor weather.

3. Preparing the Roof Structure

Metal panels need continuous support lines at regular intervals. On a truss roof, that is usually done with 2×4 purlins.

Install the subfascia

Fasten a 2×6 subfascia board along the eave line.
This board acts as the backing for drip edge and the future gutter system.

Install 2×4 purlins

Run 2×4s perpendicular to the rafters or trusses.
Space them at 24" on center up the slope.
Nail each 2×4 into the trusses using 16d framing nails (or equivalent screws at least 3" long).

At the ridge:

The last purlin near the peak should be set so the center of the board is 5½" down from the ridge.
That spacing allows room for the future ridge cap fastening line without weakening the peak.

This grid of 2×4s is the backbone the metal panels will be screwed into.

4. Underlayment: Sound Deadening and Vapor Barrier

To soften rain noise and provide a vapor barrier, the build used thin foil-faced foam boards.

Cutting and installing foam

Cut the first sheet 1½" narrower so its seams align nicely with the purlins.
After a few cuts, batch cutting with a circular saw works faster. Set the depth shallow and cut several boards at once.
Lay the foam boards flat over the 2×4 purlins, foil facing outward.
Tack them down with cap nails. A handful of nails per sheet is enough in calm conditions, but stronger winds will require more fasteners.

The foam does not carry structural loads. It simply rests on the purlins and provides acoustic and moisture benefits.

5. Drip Edge: Starting the Metal Trim

Drip edge protects the fascia and guides water into the gutter.

Ordering and pitch

Drip edge is normally pre-bent at the metal supplier.
Always specify roof pitch so the bend matches the slope.

Where to start

Start on the side of the building that sees less traffic.
That way, overlap seams are less visible from the primary approach side.

Preparing the first drip edge

On the nailing flange, measure back about ½" from the end and mark it.
Use a speed square to draw a perpendicular line.
Cut along that line with tin snips.
Snip along the crease at the face so the end can wrap around the rake.

To form the wrap:

Rest the drip edge on some stacked 2×4 scraps so the bend line lines up with their edge.
Press the metal down along the 2×4 edge and use the hammer’s backside to bend the flap over.
This bent flap will wrap around the rake and help create a watertight corner.

Creating the overlap

On the face side:

Trim about a 2" long triangular section so the next drip edge can slide over cleanly.
On the next piece, open the hem slightly so it can slide over that angled end.

When installed, each piece overlaps the previous one by about 2". One inch might work, 3" is generous, but 2" is a good standard.

Installing the drip edge

Position the first piece so the wrapped end hugs the rake.
Nail through the upper flange into each 2×4 purlin using roofing nails. About every 2 ft is typical.
Remember that the first row of panel screws will also go through the drip edge, so there is no need to over-nail.
Continue along the eave, sliding each new piece into the previous one’s hem, keeping it straight and tight.

6. Rake Edge Trim

Rake edge protects the gable edge and covers the cut ends of the panels.

Finding the angle with a speed square

The example roof uses a 4½/12 pitch. To cut the rake edge:

Lay the rake trim flat.
Place the pivot of the speed square at the outer edge.
Rotate the square until the “common” scale reads 4½ at the edge.
Mark along the square to get the correct angle.
Extend that line to a 45° cut where needed to finish the end neatly.

Cut along the lines with tin snips.

Installing the rake edge

Place the angled end at the eave so the exposed face lines up with the drip edge.
Set the back leg over the roof sheathing or foam and down onto the purlins.
Nail into each purlin up the rake.
For upper pieces, measure from the peak down to the overlap point on the existing rake, cut to length, and open the hem where necessary so the new piece can slide over the previous one.

Care at the peak is important, because that cut is clearly visible from the ground. Take the time to get that angle clean and tight.

7. Laying Out the Screw Pattern on Panels

The example panels are 29 gauge with 36" coverage and ribs every 9". Screws are placed beside the ribs in the flats, not in the center of the flat.

Overhang and first screw row

Target eave overhang: about 1" past the drip edge.
First row of screws: about 2⅜" up from the panel bottom to hit the center of the first purlin once overhang is set.

Creating a consistent pattern

The build used a “ledger” board with the measurements to each purlin center. Two options here:

1) Drilling through the whole stack

Clamp a stack of panels perfectly flush at the bottom.
Measure to each purlin location and drill an ⅛" pilot hole through all sheets.
This pre-locates screw positions, but drill bits break easily in stacks and the holes are permanent.

2) Dimpling with a punch (recommended)

Use a punch and hammer to create dimples at each screw position.
The dimple propagates down through several sheets.
The dimples give a visible point for the screw tip without weakening the panel if anything needs to be adjusted.

Dimpling avoids permanent holes and typically proves faster and more forgiving.

8. Inside Closures at the Eaves

Open ribs at the bottom of panels are entry points for wind-blown rain and insects. Inside closures solve that.

Inside closures are foam strips shaped to match the panel’s rib profile.
They usually have adhesive backing under a peel-off paper.

Installation:

Peel the backing and stick the inside closure to the underside of the panel 2" up from the bottom edge.
Make sure the profile aligns with the ribs.
These closures will sit directly on the drip edge once the panel is in place and seal the bottom opening.

9. Installing the First Panel

The first sheet sets the line for the whole side of the roof.

Orientation

Each panel has one side with an extra flat beyond the rib and one side that stops at the rib.

The side with extra flat goes down first.
The next panel overlaps on top of that extra flat so the finished lap looks clean and sheds water properly.

Positioning

Slide the panel onto the roof from the ground or scaffold.
Align it flush with the rake edge.
Set the overhang at the eave to about 1".
Measure from the drip edge to the rib to confirm the overhang is consistent.

Tacking the panel

Use 1½" self-tapping roofing screws with neoprene washers and metal caps.

Put a screw in near the top to lock the panel in place.
Add a screw at the bottom and one in the middle to keep it from walking.
When driving screws, keep the driver perpendicular to the roof so the washer compresses evenly.
Tighten until the washer flattens slightly. Do not crush or mushroom it.

The full screw pattern can be filled in later, once several panels are set.

10. Installing Remaining Panels & Squaring to the Rake

Each subsequent sheet:

Overlaps the previous sheet on the rib side with the shorter flat.
Gets its inside closure near the bottom.
Is aligned so its ribs stay straight and parallel.

Checking square at the far rake

As the run approaches the opposite rake, small alignment errors can add up. To correct:

Measure from the top rake edge to a chosen rib near the last panels.
Measure the same from the bottom rake edge to that rib.
Compare. In the example, the bottom was ¾" wider than the top.

To correct that, use “shrink” and “stretch” tricks over the last 4 to 5 panels.

Shrinking at the top

Remove a temporary screw in the upper middle of a panel.
Lift the mid-panel slightly toward the starting rake and re-drive the screw.
This almost invisibly tightens the rib spacing and reduces the top width.

Stretching at the bottom

At the eave, place a temporary screw at the edge.
Lift the panel slightly away from the starting rake and angle a screw in, stretching the distance at the bottom.
After the side screws are installed, remove that angled screw and replace it with a screw driven straight in.

By making small adjustments on several panels, it is possible to correct most of the ¾" difference so that the last panel lines up neatly with the rake edge.

Cutting the last panel

When the remaining gap is narrower than a full panel:

Measure from the rib to the rake edge at top and bottom.
Transfer that width to a full panel.
Snap a chalk line along the panel to mark the cut.
Use a metal shear attachment on a drill or impact to cut along the line.

Cutting down a rib is easier and cleaner with a shear attachment compared to hand snips, especially over a long length.

Install the ripped panel like the others and tweak the alignment as needed so the finished edge looks straight from the ground.

11. Fascia and Bird Box Details

With panels installed, the fascia metal finishes the eaves and the ends of any “bird boxes” (soffit returns at the gables).

Wrapping a bird box corner

Cut the fascia so it can wrap the corner.
Trim a small tab, then use a scrap 2×10 as a straight edge to bend the metal to form a clean corner.
Slide the fascia under the drip edge and align it along the bird box.
Fasten it with screws through the bottom flange into the soffit groove and through the face into the framing, spaced every 2 or 3 ft.

Where material is short, it is fine to piece in small strips that will be hidden by the main fascia.

Running fascia along eaves and rakes

Overlap fascia joints by at least an inch.
Wrap the far gable similar to the first, so both sides match visually.
On rakes, slide fascia under rake trim where needed, trace the profile, cut it, and secure it so it follows the trim cleanly.

12. Gable Trim (Corner Trim)

Gable trim covers the panel edges and gives the roof a finished look along the gables. It also can serve as corner trim on vertical metal walls.

Measuring for gable trim

On the lesser seen side:

Measure from the bottom edge of the metal to the peak along the slope.
Note the overhang of the roofing beyond the bird box. In the example, about 1¼". The gable trim should not extend beyond the bird box where the gutter will run.

Because gable trim has a raised leg that sits over the ribs, that leg might stand about ¾" above the roof. To keep the trim correctly positioned:

Measure from the outer edge of the gable trim back to the point where it will sit on the metal.
Subtract the ¾" height difference to find the proper setback from the roof edge for the trim.

Cutting for pitch and overlap

At the top:

Mark total length from peak to eave plus any needed overhang.
Mark down ¾" from the top edge to allow for the raised leg sitting over ribs.
From that point, mark back about 1¼" for the overhang past the peak.
Cut the roof-side leg at the exact roof pitch (4½/12 in the example).
Square a cut back from that to create a tab that hides behind the overlapping trim on the opposite side.

Installing gable trim

Transfer the calculated setback measurement (for example, 4¾") from the panel edge up at the peak and down at the eave and mark it.
Set the trim so those marks line up with the outer edge of the trim.
Tack it in place with a screw.
Use a framing square to check that the trim is square to the ridge and adjust as needed.
Once satisfied, screw along the roof leg into the ribs at the pre-marked screw locations and along the fascia leg into framing.

On the opposite side, cut the visible top end cleanly to the exact pitch, allowing about 1" overlap past the peak so the two gable trims meet neatly.

Where gable trim ends at the ridge, small pieces of foam closure can be stuffed into gaps to keep bats or birds from entering.

Finally, run a bead of color-matched sealant in the crease between trim and panels to prevent water from wicking up under the legs.

13. Ridge Cap and Venting

The ridge can be either solid or vented. The example uses a vented ridge.

Closures: solid vs vented

Solid outside closures match panel ribs and block air and moisture completely.
Vented closure rolls allow warm air to escape while keeping out rain and insects.

For a vented ridge:

Use vented closure tape instead of solid foam pieces.
Leave a consistent gap at the ridge between panel tops (already set during purlin layout).

Preparing ridge caps

Standard ridge caps often come in 10 ft 4 in lengths. With a 62 ft ridge:

Start with a shorter first piece (about 6 ft) so the far end does not end on a tiny 2 ft piece.
Lap subsequent caps about 4 in over the previous one.

On the starter piece:

Leave about 4 in at the gable end without vent tape, since that area is over solid gable trim and not venting.
Run the vent tape from that point almost to the other end.
At the very end near the gable, add a small extra piece of tape to block any wind-driven rain that might blow under the edge.

On intermediate pieces:

Start vent tape 4 in from the end that will overlap the previous cap.
Run it flush to the far end.

Always stick vent tape to the ridge cap, not the panels. That uses less tape and ensures a straighter, more uniform seal.

Installing the ridge cap

Use 2" roofing screws so they can pass through the ridge cap, the vent, the panel rib, and into the purlin.

Place the starter cap at the ridge and center it so the overhang is equal on both sides.
Push it down firmly so the vent compresses and the cap sits tight on the ribs.
Drive a screw through a rib on one side near the end.
Move to the opposite side, align, and drive a screw through a rib there.
Work along the cap, screwing every other rib on both sides.

To help alignment over long runs, a chalk line can be snapped along each side of the ridge to mark where the edges of the caps should land.

At each overlap:

Apply a generous bead of color-matched sealant across the width of the installed cap, just below the upper edge where the next cap will sit.
Set the next cap in place with about a 4 in overlap.
Center it and fasten as before.

Repeat until the entire ridge is covered. The last piece is cut or selected for length, set into the sealant from the previous piece, and screwed down flush with the gable trim.

The result is a straight, vented ridge that allows hot air to escape while staying weather-tight.

14. Flashing a Vent Pipe Through Metal Roofing

Penetrations must be handled carefully so they do not leak.

Cutting the hole

The example uses a Malco HC1 style hole cutter adjusted to 4" for a 3" vent pipe.

Choose a flat area between ribs. Avoid cutting over ribs.
Drill a small pilot hole through the metal at the center point.
Insert the cutter’s pivot point into the pilot hole.
With the drill attached, push gently until the cutting edge punctures the metal.
Run the drill at full speed and rotate the tool clockwise around the pivot, keeping light, even pressure.
Once the circle is cut, remove the steel slug and cut away any foam underlayment blocking the opening.

Preparing the pipe boot

Pipe boots are marked with size ranges.

Identify the ring closest to the pipe size (3¾" ring for a 3" pipe in the example).
Cut along that ring with a sharp knife or snips.
Slide the boot onto a length of vent pipe and check that it fits snugly.

Installing the boot

Apply a thick bead of color-matched sealant around the underside of the boot flange.
Slide the pipe and boot assembly down through the hole until the flange sits flat on the metal.
Press the boot into the sealant so it spreads under the entire flange.
Fasten the flange with 1½" roofing screws, starting at the corners, then infilling between.
Smooth and tool the sealant edge around the boot so there are no gaps.

From above, the boot should look tight, clean, and well seated. From below, the foam and metal edges around the pipe should be sealed.

15. Cost Snapshot (Example Project)

For context, the project described is:

28 ft wide by 60 ft long
1 ft overhangs
4½/12 roof pitch
Screw-down 29-gauge panels, trim, ridge, closures

At the time of that build, the metal package (panels, trim, ridge cap, closures, screws, boots, sealant) was about $5,000 in material, excluding wood framing and structural lumber.

Actual cost will vary with:

Panel gauge and coating
Color and finish
Supplier and region
Metal prices at the time of purchase

Still, it shows that a mid-size building can be roofed in metal for a relatively modest material budget when the labor is done in-house.

16. Final Checks and Maintenance

Once everything is installed:

Walk the roof carefully and inspect every screw head. Replace any over-driven or crooked screws.
Check all overlaps on drip edge, rake edge, gable trim, and ridge caps. Add sealant where there is potential for wind-driven rain.
Confirm closures are in place at eaves and ridges.
Make sure all boots and penetrations are tightly sealed and fully screwed down.

Over time:

Inspect the roof periodically, especially after major storms.
Look for damaged screws, shrinking washers, or sealant failures near penetrations and overlaps.
Replace screws and touch up sealant where needed.

Done correctly, a screw-down metal roof like this can provide decades of service, with straightforward maintenance and a relatively low upfront cost.