Metal and Colorbond roofing along the mountains ridge

Why steel suits this ridge

Steel sheeting has three advantages that matter specifically up here, and they are physical rather than promotional.

It is light. On a steep mountain pitch, replacing a tiled covering with steel takes a significant dead load off the frame, which is useful on the older timber-framed stock through Woodford, Lawson and Mount Victoria.

It sheds. There is no mortar bedding to break down, no deep tile profile to trap eucalypt leaf and bark, and a steep steel pitch clears water, litter and settled snow far faster than tile.

It does not burn. On mapped bush fire prone land, with roughly 70% of the local government area sitting inside Blue Mountains National Park, a non-combustible covering makes the rest of the bushfire detailing simpler to get right.

Call (02) 4703 5000 and we will come out, measure up and put a written quote in front of you at no cost.

Profiles, and which house each one belongs on

• Short-run corrugated. The default for a weatherboard cottage, a Federation bungalow or anything inside a conservation area. It is what the original mountains stock wore and the shadow line looks right on a steep pitch.
• Trapezoidal rib. Efficient over long spans and low pitches, so it earns its place on a modern extension, a carport or a shed. It looks out of place on a heritage roofline.
• Concealed-fix standing seam. No exposed fasteners, very clean, good for low pitches and architectural work. More expensive, and the clips and span tables have to be right.

Pitch also decides things. Many mountains roofs were built steep deliberately, to throw water and leaf litter off quickly, and a steep pitch opens up the profile choice. A near-flat verandah or skillion narrows it fast.

Fixings, laps and thermal movement

Steel moves with temperature, and the temperature swing here is larger than on the coastal plain — frost before dawn, full sun by mid-morning. Over a long run that movement is real, so fixings need to be correct type, correct spacing and driven to the right depth: too loose and the sheet works at the fastener, too tight and the washer is crushed and stops sealing.

Side laps and end laps have to face the right way for the prevailing weather, and in fog-prone locations capillary action will pull water uphill through a lap that has been laid lazily. Most of the "mystery leaks" we get called to on metal roofs are a lap, a fixing or a flashing — rarely the sheet.

Condensation, the thing that gets missed

This is the single most common specification failure on metal roofs above 600 metres. The sequence is simple: the interior is warm and carries moisture from showers, cooking and drying clothes; the underside of the steel is near or below freezing; moisture condenses on it and runs off onto insulation and ceiling timbers.

Homeowners report it as a leak. It is not. The fix is in the build:

• Sarking with an absorbent anti-condensation face, laid and lapped correctly and turned into the gutter.
• Adequate ceiling insulation, so the warm side stays on the warm side.
• Real ventilation — intake low at the eaves, exhaust high — so moist air leaves the roof space instead of sitting against cold steel.

Colour, in bushland and in a heritage street

Two different conversations, sometimes on the same house.

On a bush block the muted greys, greens and charcoals disappear into the canopy and stay cooler in summer than a dark gloss would, while light colours show lichen staining badly in a damp, shaded position. On a street inside one of the Katoomba or Leura conservation areas the question is different: the controls in Blue Mountains LEP 2015 and Part D of the Development Control Plan put material, profile and colour in scope, and a strong modern colour on a Federation roof will attract attention. Muted, traditional tones are both the safer planning answer and generally the better-looking one.

The bushfire detailing

Where a Bushfire Attack Level applies to your property under AS 3959, the roof is one of the elements it governs. In practice that means a fully sarked roof, a sealed roof-to-wall junction, non-combustible ember guards to openings and penetrations, metal gutters, and any box gutter non-combustible and fully flashed. Note that a leaf guard and a certified ember guard are different things even where one product claims both — check what the certification actually covers.

A steel roof does not exempt you from any of that, but it starts you from a non-combustible covering, which is a better starting point than a tiled roof with open tile ends.

Over the top of tiles, or strip it properly

We will not quote sheeting laid over an existing tile roof. It traps the old covering and whatever moisture is in it, loads the frame with weight it was never designed to carry permanently, and makes any future access or repair far worse. A proper roof replacement strips to the frame so battens, sarking and insulation can be inspected and renewed.

If your existing tiled roof is sound and you simply want it to look and perform better, roof restoration is usually the cheaper and more sensible option, and we will say so.

Getting a number

Ring (02) 4703 5000 or send the form with your roof type, its approximate age and what you are trying to achieve. Roof area, pitch, profile choice, access and any BAL or heritage requirements are what move the price, and the quote comes after someone has been on the roof — not before. Work is carried out by established, licensed and insured roofing contractors working to NSW Fair Trading requirements, with a written workmanship warranty.