Metal Roofing near you

The single most consequential line on a metal roofing quote is the coating, and most homeowners never read it. Part 7.2 requires metal sheet roofing to be protected from corrosion in accordance with its corrosion protection table, which sets coating classes against the severity of the environment, with the heavier zinc, aluminium-zinc and aluminium-zinc-magnesium coatings reserved for harsher exposures. Distance from breaking surf, prevailing wind, industrial atmosphere and whether a roof surface is washed by rain or sheltered from it all feed into which class is appropriate. Specify for the address, not for the catalogue photograph.

Metal compatibility is the second rule, and it explains failures that look inexplicable from the ground. The Code is explicit that no lead materials can be used upstream from aluminium and zinc coated materials, that no lead materials can be used on roofs forming part of a drinking water catchment area, and that no copper materials can be used upstream from galvanised coated materials. Runoff carries the more noble metal downhill onto the less noble one and eats through it. An old lead flashing, a copper pipe or a copper hot water overflow discharging onto a modern coated steel roof will bore a hole in it, and replacing the sheet without removing the source simply restarts the clock.

Then the components that live with the sheet for its whole life. Flashings must be purpose made, machine-folded sheet metal sections of material compatible with all upstream and downstream metal roof covering materials, which rules out flashings improvised on site out of whatever offcut is handy. Fasteners, sealing washers, gutter brackets and rainwater goods all have to belong to the same compatibility family as the sheet. Where the roof feeds a tank, the prohibition on lead reaches into the gutters and downpipes as well.

The numbers that decide whether a sheet roof leaks are mostly about laps and pitch. The Housing Provisions set a minimum end lap of 150 millimetres for roof slopes above 15 degrees, and 200 millimetres for slopes between 5 and 15 degrees, because the flatter the roof the further water can creep back up a joint. Minimum pitch itself is set by profile, and a profile laid flatter than it is rated for will let water track under laps no matter how well it is screwed down. Side lap fastening is also prescribed by profile and by whether the sheet is in an end span or an internal span, so a fixing pattern is not a matter of preference.

Wind classification sets the rest. Part 7.2 may be used as the deemed-to-satisfy route only where the building is in an area with a wind class of not more than N3; beyond that the roof is designed to AS 1562.1 and the structural standards rather than to the housing tables. In wind regions B, C and D, the cyclonic provisions apply, and the requirement is that the metal roof assembly, its connections and its immediate supporting members remain in position notwithstanding any permanent distortion, fracture or damage in the sheet or fastenings under the defined pressure sequences. In practice that is a whole-building requirement: the Code describes an anchorage system in which the roof is connected by the walls to the footings by a chain of connections, with each connector capable of carrying the uplift force and each structural element interlocked to its neighbour throughout the building.

So ask three things of any re-roof quote. What wind classification has been used for this address and how was it determined. What coating class is being supplied and why that one here. And what happens, in writing, if battens or roof timbers are found to be damaged once the old covering is off, since nobody can see them beforehand and that is the most common variation on the job.

Condensation is the Australian sheet-roof problem that homeowners discover late. Metal has almost no thermal mass, so on a clear night the sheet radiates heat away and its underside can fall below the dew point of the air beneath it. Moisture then forms on the underside of the sheet and drips onto sarking, insulation, ceiling linings and framing. Because it happens overnight and dries during the day, it is routinely reported as a mystery leak that appears without rain, and it is chased as a leak for years.

The Code now addresses this directly in the condensation management provisions. A pliable building membrane installed in an external wall must comply with AS 4200.1 and be installed in accordance with AS 4200.2, and the vapour permeance required of materials on the outside of the primary insulation layer differs by climate zone, with a higher permeance required in climate zones 6, 7 and 8 than in zones 4 and 5. In those same colder zones, a roof space must be ventilated to outdoor air through evenly distributed openings sized in accordance with the Code's roof ventilation table, maintaining a height of not less than 20 millimetres, unless it sits immediately underneath the roof tiles of an unsarked tiled roof. The opening areas the table requires are largest on the lowest pitches, which is exactly where the skillion and low-pitch metal roofs sit. Exhaust air makes it worse if it is dumped into the roof space: the Code requires exhaust from a kitchen, range hood, bathroom, sanitary compartment or laundry to discharge directly or via a shaft or duct to outdoor air.

Licensing is a state matter and metal roofing is often split between trades. In New South Wales, roof plumbing is a licence class of its own, defined as any work involved in fixing, installing, renovating, altering, repairing and maintaining guttering, downpipes, roof flashing and roof coverings on any building or structure, and extending to putting in skylights, ventilators and the like and to protective coatings that do not involve structural changes. A contractor licence is required once building or trade work passes the value threshold in the Home Building Act, and the Act carries substantial penalties for contracting without one. In Queensland the QBCC issues roof and wall cladding as a trade class that covers selecting and installing roof cladding other than terracotta and concrete roof tiles, fabricating and installing rainwater goods, flashing penetrations through roofs and walls, designing roof drainage components, and refurbishing and maintaining roofs other than painting them, and a QBCC licence is required for building work above its value threshold and for plumbing or drainage work of any value. In Western Australia only a registered building practitioner or registered building contractor may carry out particular building work, under the Building Services (Registration) Act 2011, with the Building Services Board as the registration authority supported by Building and Energy.

Approvals are a separate question with a local answer. Replacing a covering like for like is often treated as repair or maintenance, but changing the roof form, the pitch, the structure or the material weight is not, and converting a tiled roof to sheet changes the load on a structure designed for tiles. On designated bushfire prone land the house and its associated Class 10a buildings and decks must be designed and constructed to reduce the risk of ignition from burning embers, radiant heat or flame, with the deemed-to-satisfy path being AS 3959 at the assessed bushfire attack level or the NASH steel framed construction standard. Your council or a private building surveyor gives the definitive answer for your postcode and your address.

LokalMatch is the step before all of that. You describe the metal roofing job once, with the existing covering, the roof area and pitch, the number of storeys, how close you are to the coast, and whether there are solar panels or a rainwater tank, and matched roofers and roof plumbers come back to you. Those businesses pay for the requests they receive. LokalMatch does not install roofing, does not set or quote prices and does not vet, rank or recommend any business, so the licence check on your state regulator's own register, and the question of which licence class covers which part of the job, remain with you.

Within metal roofing the first choice is how the sheet is held down. A pierced-fix roof is screwed through the sheet into the batten, with a sealing washer at every fastener. It is the Australian default, it is economical, it is easy to inspect from above, and its weak point is the fastener: washers perish, screws back out slightly, and every penetration is a potential path. A concealed-fix or standing seam roof is held by clips with no fastener through the weather surface, which removes that path and allows the sheet to move with temperature, but it is a more specialised installation and repairs mean understanding the system rather than replacing a screw.

Against tile, the real differences are weight, pitch and repairability. Tiles are heavy and the structure of a tiled house was designed for that load, so going from tile to sheet lightens the roof and usually involves reworking battens and sometimes other details, while going the other way is a structural question for someone qualified rather than an assumption. Sheet sheds water at lower pitches, which is why skillion and low-pitch designs are almost always metal. Tile is repairable one unit at a time and forgiving of foot traffic in a way that a creased sheet is not.

Exposure settles the rest. In a cyclonic region the roof is part of an engineered load path and a system whose tie-down can be specified and inspected is an advantage. Near surf, coating class and fastener metallurgy matter more than profile. And where the roof feeds a drinking water tank, the material of every flashing and every gutter is a health question, because the prohibition on lead in a drinking water catchment admits no exceptions.