Metal siding and standing seam cladding

What we clad with metal

Most of our siding work is one of three things. Accent areas on a house: a gable end, the cheeks of a dormer, a bump-out, a chimney chase, or the wall under a covered entry. Whole elevations on new builds and major renovations, usually combined with wood, stone or stucco on the other walls. And the trim that every house has: soffit, fascia, and the wrap on window and door openings.

We also clad commercial buildings, with standing seam on walls or ACM cassette panels on facades and entrances, and cottages and boathouses, where metal walls are taking the place of wood that needed staining every few years. Our article on metal siding and cladding covers orientation, panel widths and colour choices for walls. Below is what we install, what sits behind it, and how a wall project fits in with a roof.

Steel or aluminum siding: which one for which wall

Both are good materials, and the right one depends on where the wall is and what it has to put up with.

• Steel is stiffer, so it holds a flatter face over a wide panel and resists dents from ladders, balls and snow thrown off a driveway. It is our usual choice for standing seam on walls, especially at ground level, and it lets the wall come from the same coil as a steel roof.
• Aluminum does not rust, which makes it a strong choice where a wall sits in road-salt splash beside a driveway, or right at the shoreline. It is lighter and softer, so it dents more easily at reachable heights.
• For soffit and fascia, both work well. Aluminum is the most common and is easy to match to eavestrough; steel is used when the fascia needs to match a steel roof edge in colour and finish exactly.
• Mixing the two on one building is normal. What matters is that dissimilar metals are not fastened directly together, and that fasteners are compatible with the panel.

Strapping and a drained cavity behind every metal wall

Metal cladding keeps most of the weather off a wall, but wind-driven rain and condensation will get behind any siding at some point. The wall has to be built so that water drains down and out, and the sheathing can dry. That is called a rainscreen, and it is good practice for any cladding, not only metal.

On our walls that means a weather-resistive barrier lapped properly over the sheathing and into the window and door flashings, then strapping fixed through it into the studs to create an air space, then the panels on the strapping. The bottom of the cavity is screened against insects and left open to drain, and the top is vented or closed depending on the wall. Strapping orientation follows the panel: vertical panels go on horizontal strapping with a drainage path, horizontal panels go on vertical strapping. A metal wall fastened straight onto the sheathing with no gap is cheaper to build and more likely to cause trouble later.

Over the old siding, or off with it

We are often asked whether metal can go straight over existing vinyl or wood siding. In most cases we take the old siding off. With it in place, nobody can see whether the sheathing behind is sound, the weather barrier cannot be lapped properly into the window and door flashings, and the new wall ends up thicker than the trim around the openings was designed for.

Taking it off also tends to answer questions the owner did not know to ask: soft sheathing below a leaking window, a missing barrier, or gaps where cold air has been getting in. Those are cheap to fix with the wall open and expensive to find after it is clad. Brick and stone walls are a different case, and how to clad over masonry is decided on site.

Matching a metal roof, run for run

Because the roll former comes to the property, wall panels can be formed from the same coil, on the same day, as the roof above. Colour matches as closely as two pieces of the same steel can, the seam profile matches, and the panel width can be chosen for the wall rather than whatever a supplier has in stock.

It also lets the roof and wall be detailed together. A standing seam roof that turns down a dormer cheek, a gable end where the roof panels and the wall panels line up seam for seam, or a porch roof that runs into a metal wall with a single flashing bent to suit: these are easier to get right when one crew is doing both, from one coil, at the same time.

Soffit, fascia and the trim that frames a house

Metal soffit and fascia replace painted wood that rots at the ends and peels every few years. The soffit is also the intake for the attic ventilation, so we use vented soffit along the eaves wherever the roof needs intake, and we check that insulation is not blocking it before closing it in. Solid soffit goes where venting would serve no purpose, such as a porch ceiling.

The trim around windows and doors and at the outside corners is bent on our brake to fit the openings that are actually there, not a stock profile that almost fits. Head flashings over windows tie into the weather barrier behind the cladding so water is turned outward rather than into the wall. On a re-roof with tired soffit and fascia, doing the eaves at the same time saves a second set-up, because the access and the crew are already on site.

ACM panels and commercial facades

On commercial buildings, the flat, crisp look of storefronts and entrances usually comes from ACM, aluminum composite panels routed and folded into cassettes and hung on a subframe. We install ACM where the drawings call for it, built to the panel and core the design team has specified for that building. Combining ACM facades with standing seam roofing and coping on one building gives the owner one trade responsible for where they meet, which is where commercial walls tend to leak.