Frequently asked questions
The questions worth answering properly.
Section
Products & systems
Choosing between profiles and systems.
On an exposed-fix roof the sheet is screwed through its face and the fastener heads are visible in regular lines across the roof. On a concealed-fix roof the sheet is held by clips hidden inside a seam, and nothing penetrates the weathering surface at all.
Exposed fixing is faster, cheaper and — with the right fastener, the right torque and a sound washer — entirely durable. Concealed fixing removes the fastener as a maintenance item altogether, allows the sheet to move freely as it heats and cools, and works at lower pitches. It also costs more.
For a straightforward pitched roof, exposed fixing is usually the sensible answer. For a low pitch, a long plane, an exposed site or a building where the roof is architecturally visible, specify a concealed-fix system.
Three things decide it: the pitch of the roof, the distance between supports, and how the building should look.
Pitch sets the minimum. Every profile has a lower pitch limit below which a lap or a seam will not stay watertight under driven snow, and the mechanically seamed systems go lowest.
Support spacing sets the depth. A shallow profile over battens or a deck is fine; widely spaced purlins need a deeper section, and at the deep end the sheet becomes structural and can take purlin lines out of the frame entirely.
Appearance decides the rest. Send us the pitch, the span and a drawing and we will narrow it to one or two options before you commit anything to paper.
Yes, and it is one of the more effective things you can do with metal. Because roof profiles and wall profiles come off the same lines in the same coatings and colours, an envelope can be specified as one material that folds from facade to roof.
Some products are explicitly designed for both — flat-lock panels and corrugated sheet run vertically or horizontally with no change of detail. Others pair: a trapezoidal roof with a micro-rib or trapezoidal wall in the same colour.
The important thing is to order roof and wall from the same coating batch where possible, so the two surfaces match exactly rather than approximately.
Yes. Bespoke folding is a standing capability, not an exception — the brakes that produce our catalogue trims produce made-to-drawing work on the same coil.
Send a drawing, a sketch or a site survey with dimensions. We return a folded profile drawing for approval before anything is produced, so what arrives is what you intended.
The advantage of ordering the bespoke work with the roof is an exact match: same coil, same batch, same gloss. A trim sourced elsewhere in the same nominal colour rarely matches once it is on the building.
Section
Materials & coatings
Steel, metallic coatings and paint systems.
Hot-dip metallic coated structural steel to European standards, coil-coated with an organic paint system on the weather side and a protective backing coat on the reverse.
The metallic coating under the paint is what actually protects the steel — the paint provides colour, UV stability and the first line of mechanical protection, while the zinc or zinc-aluminum layer beneath does the electrochemical work, including at cut edges.
Grade, thickness and metallic coating weight are specified per product and confirmed on the data sheet issued with your quotation.
Coating systems differ in film thickness, the resin chemistry and therefore how they age. Standard polyester is the economical volume system. Matt polyester adds a low-gloss surface that hides substrate irregularity. Polyurethane builds a thicker, tougher film developed for northern climates. PVDF is the most colour-stable option available on coil-coated steel. Plastisol is a thick PVC film chosen for mechanical and abrasion resistance rather than appearance.
In practice the choice is driven by exposure and expected service life rather than by colour. A sheltered agricultural building and an exposed coastal facade should not be specified in the same system.
A gloss finish reflects light, which makes a roof look brighter and shows the plane of each surface clearly. A matt finish scatters light, so the roof reads as one flat tone and small irregularities in the substrate become far less visible.
On large uninterrupted planes, and on any roof where the deck is not perfectly flat, matt is the safer choice. It is also the dominant finish in contemporary Nordic architecture for exactly that reason.
Gloss levels vary between coating systems, so compare physical samples rather than descriptions.
A correctly cut edge on metallic-coated steel does not rust in normal service. The zinc or zinc-aluminum coating protects the exposed steel at the edge electrochemically over the small distances involved.
Two things break that protection. The first is cutting with an abrasive disc, which burns the metallic coating away either side of the cut and throws hot filings across the sheet, where they embed and rust as visible orange specks. The second is severe exposure — heavy marine or industrial atmospheres, where we specify edge sealing and a higher coating class from the outset.
Cut coated steel with a nibbler, shears or a cold-cut saw. Never with a grinder.
Yes, and it should be raised at quotation rather than discovered later. Salt-laden air is a more aggressive environment than an inland site, and the correct response is a co-ordinated one: a higher coating class, a higher fastener corrosion class, edge sealing where relevant, and a maintenance regime that includes rinsing.
Tell us the distance to open water and the prevailing wind direction when you request a quote and we will specify against it.
Every organic coating changes slowly under ultraviolet light. How slowly depends on the coating system, the colour and the orientation of the surface — south-facing planes age faster than north-facing ones, and saturated colours show change earlier than neutrals.
The practical answer is to match the coating system to how much the building can tolerate. Where colour stability is critical, specify a fluoropolymer system. Where it is not, a polyester will change gradually and evenly over many years.
Warranty terms for each coating system are confirmed with your quotation.
No, and no website's are. Coated steel changes appearance with gloss, surface texture, viewing angle and daylight, and every screen renders colour differently.
Use the palette on this site to shortlist. Confirm the final choice against a physical VANKKA sample, viewed outdoors, in the orientation the building will actually face.
Section
Performance & climate
Snow, wind, condensation, noise and heat.
It carries it and then, at some point, sheds it — usually all at once, on the first warm day.
Carrying it is a structural question answered by the profile's load-span table against the design snow load for the site. Shedding it is a safety question: above an entrance, a walkway or a parking area, a roof that releases its snow load without warning is a hazard, and snow retention should be specified there.
In Finland snow retention is treated as part of the roof rather than an accessory, and we size it — bar count and bracket spacing — against pitch, plane length and design load as part of the quotation.
Wind uplift is resisted by the fixing pattern, not by the weight of the sheet. A correctly specified and correctly installed metal roof performs extremely well; a roof fixed to a generic pattern in an exposed location does not.
The specification depends on the site's design wind load, the building height and shape, and the zone of the roof — corners and edges see far higher local pressures than the field of the roof and are fixed more densely as a result.
We issue a fixing pattern with the project documentation. Following it is the single most important thing an installer does.
Steel is a good conductor, so on a clear night the underside of the sheet drops below the dew point of the air beneath it and moisture condenses on it. This is physics, not a defect — it happens under any cold roof surface.
It is prevented by controlling the air, not the metal. In a ventilated cold roof, a continuous cavity above the insulation lets air enter at the eaves and leave at the ridge, carrying moisture out with it. In an unventilated warm roof, a properly sealed vapour control layer keeps moist internal air out of the build-up in the first place.
Most condensation problems are one of two failures: a ventilation path blocked by insulation pushed into the eaves, or a vapour control layer that was never sealed at its joints. Both are build-up decisions made long before the sheet arrives.
Not in a normal build-up. The perception comes from uninsulated agricultural buildings and garden sheds, where a single sheet is fixed to open purlins with nothing beneath it.
In a habitable building the sheet sits over an underlay, a ventilated cavity, insulation and a ceiling. Each of those absorbs and decouples sound, and measured differences between a metal roof and a tiled one in a comparable build-up are small.
It generally does the opposite. Coated steel reflects a meaningful share of incoming solar radiation and, being thin with very low thermal mass, it also releases the heat it does absorb quickly once the sun moves off it. A heavy tiled roof stores heat and continues radiating it into the loft for hours.
Colour matters more than material here — a dark roof absorbs more than a light one in any material — and so does ventilation of the cavity beneath.
No. Lightning is governed by the height and geometry of a structure and its surroundings, not by the conductivity of its roof covering. A metal roof does not make a strike more likely.
If a strike does occur, a conductive roof tends to distribute the energy over a large area rather than concentrating it, which is generally favourable. Where a building requires lightning protection, that is designed by a specialist and the roof is bonded into it.
Longer than most of the things fixed to it. Service life is determined by the metallic coating weight, the paint system, the exposure of the site and whether the roof is maintained at all.
In practice the paint system reaches the end of its aesthetic life before the steel reaches the end of its structural life — the roof stops looking new long before it stops working. Specifying a heavier coating system moves that point out considerably.
Expected service life and warranty terms for each system are confirmed with your quotation.
Section
Installation
Substrate, ventilation, fixing and cutting.
It depends on the profile. Shallow profiles and tile-profile sheet are laid over battens or a continuous deck. Deep structural profiles span directly between purlins and need neither.
Where battens are used they do more than support the sheet: with counter-battens they form the ventilation cavity that keeps the underside of the roof dry, and they give an installer something safe to walk on.
The correct substrate is specified per profile and issued with the technical documentation.
Often, yes — and it saves the cost, time and waste of a strip-off. The existing covering also acts as an additional layer in the build-up.
Three conditions have to hold. The structure must carry both coverings, which is usually straightforward given how light steel is. The existing surface must be sound and reasonably even. And a ventilated cavity must be formed above it with counter-battens, so the new roof does not trap moisture against the old one.
Where the existing covering is failing, holding water or structurally suspect, strip it.
Through the flat, in almost every case. Fixed through the pan, the fastener pulls the sheet down onto the support and the washer stays in compression against a surface that is backed by something solid.
Fixed through the rib, the fastener is clamping across an unsupported void. Repeated thermal movement and foot traffic work the fixing loose, and a loosened fastener with a relaxed washer is an open hole.
The exception is certain deep structural and corrugated profiles where crown fixing is specified deliberately. Follow the fixing pattern issued with the profile.
With a nibbler, hand or electric shears, or a cold-cut saw with a blade intended for coated steel. All of these cut without generating enough heat to damage the coating.
Never use an abrasive cutting disc. It burns off the metallic coating either side of the cut and sprays hot filings across the sheet, which embed in the paint and rust within weeks. It is the single most common cause of a roof that looks defective in its first year and is not covered by any coating warranty.
Sweep swarf off the sheet at the end of every working day, not at the end of the job.
Yes, with care and with an understanding of where the supports are. Step in the pan of the profile directly over a batten or purlin, wear clean soft-soled footwear, and stay off it when it is wet, frosted or snow-covered — a coated steel roof at pitch is extremely slippery.
Where a roof will need regular access — flues, plant, chimneys — specify walkways, roof ladders and anchor points rather than relying on care. That is what they exist for.
In a ventilated cold roof, yes, and it is not optional. The cavity has to be continuous from eaves to ridge, with a free inlet at the bottom and a free outlet at the top. Break the path at any point — insulation stuffed into the eaves, a blocked ridge closure, a flashing that seals the outlet — and the cavity stops ventilating and starts collecting.
In an unventilated warm roof the strategy is different: there is no cavity to ventilate, and the vapour control layer beneath the insulation does the work instead. It must be continuous and sealed at every joint and penetration.
Decide which of the two build-ups you are constructing before ordering, and detail it consistently. Half of each is the failure mode.
Section
Ordering & delivery
Quoting, custom production, lead times and shipping.
Start with a quote request. Tell us the building type, the roof or facade area, the pitch, the location and your timeline, and attach whatever drawings you have — even a hand sketch with dimensions is enough to begin.
We come back with a specification and a price, not just a price. If the profile you have asked for is the wrong one for your pitch or span, we will say so before you order rather than after.
For contractors and distributors ordering repeatedly, we set up account terms and an agreed product and colour range.
Yes — cutting to length is how we produce, not an extra service. Sheets are rolled to the length of the run wherever transport and handling allow, which removes transverse laps from the roof entirely.
The practical limits are transport, site access and what a crew can safely handle in wind, not the rolling line. Very long sheets need to be planned into the delivery and the lift.
Maximum lengths are confirmed for your project at quotation.
Lead time depends on the product, the coating and colour, and the destination. Stock colours in standard coatings move fastest; bespoke folding, non-stock colours and North American shipments carry longer programs.
We confirm a date with the quotation rather than quoting a general figure, because a date you can build a program around is worth more than an optimistic average.
Yes. VANKKA supplies projects across Europe from Finland, and North America through our Halifax, Nova Scotia base, which handles specification, quoting and order coordination on that side of the Atlantic.
For North American projects, sheet lengths and packing are coordinated to the shipping method, which is worth planning early — it can influence how the roof is set out.
Yes. We manufacture at scale, but a single house roof is a normal order and is specified with the same technical input as a distribution centre.
Minimum quantities apply to some bespoke folding and non-stock colours, because a coil change has a fixed cost. We will tell you where you are close to a threshold and what it would take to cross it.
Yes, and you should before committing to a colour. Screens cannot reproduce a coated steel surface, and colour choices made from a monitor are regularly regretted at first sight of the building.
Request samples through the contact form, telling us the coating systems and colours you are considering.
Data sheets, installation guides, CAD details, declarations of performance and warranty terms are collected in the technical documents area and linked from each product page.
For anything project-specific — load-span calculations, fixing patterns, bespoke fold drawings — contact the technical team directly with your drawings.
Section
Warranty & aftercare
Coverage, maintenance and service life.
VANKKA warranties cover the manufactured product: the integrity of the steel and the performance of the coating system in normal service, against defined criteria for corrosion, adhesion, cracking and colour change.
They do not cover installation workmanship, mechanical damage, damage from incompatible materials or fixings, cutting with abrasive discs, or environments outside the exposure class the product was specified for.
Terms differ by coating system and by exposure. The applicable warranty document is issued with your quotation and order.
No. VANKKA is a manufacturer — we warrant what we produce. Installation is warranted by the contractor who carries it out, and that is the correct division: we cannot stand behind work we did not do, and no manufacturer honestly can.
What we do provide is the documentation an installer needs to get it right: fixing patterns, detail drawings, installation guides and direct access to our technical team while the work is on site.
Very little, but not none. Once or twice a year: clear gutters and valleys of leaves and needles, check that nothing is sitting against the sheet trapping moisture, and inspect exposed fasteners on an exposed-fix roof for any that have loosened.
On coastal and industrial sites, rinsing surfaces that rain does not naturally wash — soffits, sheltered elevations, areas under overhangs — makes a measurable difference to coating life.
Deal with mechanical damage and deep scratches when they happen rather than at the next inspection, using colour-matched touch-up.
Usually yes, which is one of the practical advantages of metal over a fully bonded covering. On an exposed-fix roof a single sheet can generally be removed and replaced. On a concealed-fix system it is more involved but still achievable within a bay.
Keep a record of the profile, coating system, colour and production batch — it is issued with your delivery documentation. With it, a replacement sheet can be produced to match years later.
Still have a question?
Ask someone who makes the product.
Technical questions go to our engineering team, not a call centre. If it is project-specific, attach the drawings.