Standing Seam & Tray Roofing
Standing seam is a metal roof or wall cladding where the sheets join along raised vertical seams, held down by hidden clips instead of screws through the surface. The result is clean, unbroken lines with no exposed fixings.
The term gets used loosely in New Zealand, so it's worth being precise. The NZ Metal Roofing Manufacturers Code of Practice calls these secret-fixed tray profiles. Self-supporting trays span between purlins. Fully supported trays sit on a solid plywood deck, and the Code reserves the term standing seam for those. The difference changes what has to be built underneath, and what the job costs.
On a roof, standing seam is laid over a solid plywood deck, not just purlins. The deck has to be built flat, fixed to suit your wind zone and allowed room to move, or it shows through the finish. On walls, it's installed over a cavity batten system.
Tray roofing doesn't breathe as easily as other profiles, so the roof space needs a planned airflow: air in at the bottom and out at the top. Get it wrong and condensation builds up underneath.
Before a single tray goes down, the roof is set out around its key features, such as windows, skylights and edges, so the lines run evenly and symmetrically across the building.
Part of what makes standing seam look so clean is having almost no visible fixings. Where possible, flashings are folded and crimped into place rather than riveted through the surface.
In Europe, this work is its own trade with a four-year apprenticeship. New Zealand has no equivalent, which is why the Code of Practice says installers need specific training and experience with the product.
A new build gets the roof it was designed for. An existing house may need framing or substrate work before a tray roof can go on at all.
A fully supported tray needs a plywood deck that a conventional reroof does not. That is material and labour a corrugate quote never carries.
How close the property sits to the coast drives the material specification, and the coastal grades cost more than the standard ones.
Standing seam takes more preparation and installation time than conventional roofing, and needs installers with product-specific training and a higher level of skill. There's less room for error, so more of the work goes into planning before a tray is laid.
Hips, valleys, dormers and penetrations all have to be detailed by hand. A simple gable is a different job from a broken roofline of the same area.
More of the flashing set is purpose-made, and crimping and clipping is slower than riveting. The finish is better and the labour is longer.
Hidden clips mean no exposed screws or washers on the weather surface. Specified for your corrosion zone and maintained as the manufacturer requires, it suits clients looking for long-term performance and aesthetics.
Flat pans and crisp vertical seams give a clean, contemporary finish that suits modern and architectural homes. It works especially well on large, open roof planes and on walls, with a range of colours and finishes.
Continuous seams shed water efficiently, clips let the sheets move with temperature, and secret-fixed profiles can generally go on lower pitches than conventional roofing. How well it performs comes down to installation as much as the product.
Worth Knowing Before You Commit
Oil canning is visible waviness in the flat pan of a tray roof. The Code of Practice says plainly that it is always present to some degree, and that how visible it is depends as much on the light, your line of sight, the gloss level and how clean the roof is as on anything about the product itself.
Every tray roof carries some degree of canning. The question is whether you can see it, not whether it exists.
A roof that reads as flat at midday can show waviness in low sun, or when the roof runs at an acute angle to your line of sight.
A narrower pan, a low-gloss or textured finish, and a resilient strip run down the centre of the pan to give it a slight convex shape.
Anyone promising a dead flat tray roof either has not told you the whole story, or has not installed many.
Frequently Asked Questions
Yes. The same systems used on roofs can be installed on walls, over a cavity batten system.
It needs a solid plywood deck, more hand-finished flashings and installers with specialist training, and it takes longer to install. You're paying for the finish and the extra work behind it.
It's hard to give a reliable range, because the price depends so much on the roof. Is the plywood deck already built, or does the framing need converting to take a tray roof? Is it a simple gable, or does it have dormers, hips, internal gutters, junctions or wall cladding? As a general guide, the roofing itself, materials and installation, typically costs around 2.5 to 3.5 times as much as a conventional metal roof.
That depends more on the material than the profile. The right grade for your corrosion zone matters most. What standing seam does remove is exposed screws and washers, which are often the first thing to age on a conventional roof.
Wind noise can be an issue on wide trays in exposed spots, and there are proven ways to reduce it, such as narrower trays and closer clip spacing. Rain noise depends more on what sits between the roof and your ceiling than on the roof itself.
Sometimes. A true standing seam roof needs a plywood deck built over the framing, which raises the roof height slightly and can affect the fascia and spouting. It's something we assess on site.
It really shines on architectural designs: skillions, monopitch roofs, and roofs that carry down into wall cladding. On a traditional hip roof you mostly see from the street, much of its appeal is harder to notice. It's not for every property, and we'll give you an honest view before you commit.
