Are Metal Roofing Sheets Good for Houses?

Two kinds of metal covering turn up on houses. Tile-effect sheets are long steel panels pressed to look like rows of tiles, often with a stone-chip or granular finish. They are light, cover a large area quickly and are common on garages, extensions and outbuildings, and sometimes on a whole house. Standing seam is a different product: long metal strips, such as zinc, copper or aluminium, joined by raised folded seams that run from ridge to eaves. It is made up on site and is a specialist trade.

The look is the first thing to weigh. Tile-effect sheets copy a tile, but up close the profile is shallower and the colour is flat, which some neighbours and some councils notice. Standing seam looks modern and crisp, and sits happily on a contemporary extension. Neither looks like a traditional clay or slate roof, and on an older house in a street of clay tiles, the difference can be plain from the pavement.

Before choosing, ask your roofer which product they mean, what the maker's pitch limits are, and how the roof would be fixed. The minimum pitch is on the product data sheet, as it is for every covering.

Rain noise is the usual worry. A thin metal sheet fixed straight over an empty roof space can drum in heavy rain. The build-up underneath changes that: a solid deck, insulation and a ceiling below all soften the sound, so ask the roofer how the roof is built up instead of judging the sheet on its own.

Condensation is the more serious point. Metal is cold and does not absorb moisture, so warm, damp air from the house can condense on its underside if it reaches it. The answer is a correctly designed roof: a sealed ceiling, the right membrane and ventilation that suits the construction. BS 5250 deals with managing moisture in buildings, so ask the roofer which ventilation approach your roof follows. Marley's guidance on cold roofs, for example, sets out different eaves ventilation figures for different underlays, which shows how much depends on the exact build-up.

Do not let anyone quote for sheets alone. The membrane, battens or deck, the insulation and the ventilation are what stop the drumming and the drips, so the one written price should cover the complete roof build-up.

Changing the covering is not always development. Section 55 of the Town and Country Planning Act 1990 treats as non-development any work whose effect on the outside look of a building is not material. Swapping clay tiles for metal sheets plainly changes the look of a house, so it is worth putting the question to the council's planners ahead of any order. For a Crawley address that is Crawley Borough Council. In a conservation area or on a listed building the question matters even more.

Building control looks at weight and fire. Planning Portal gives two reasons approval may be needed: the new covering raises the covering's weight by 15 per cent or more, or its fire performance would be markedly different to the existing covering's. Weight and fire performance both depend on the product, so ask for the maker's evidence and check with your building control body.

Ask the roofer, too, whether the job counts as re-roofing under the Building Regulations; that turns on the share of the roof and building envelope affected.

Lifespans vary a lot by metal and by the quality of the installation. VM Zinc's FAQ gives 100 years for zinc, citing an environmental product declaration. That is a figure for one metal, not for every steel sheet sold as roofing, and a coating can fail long before the metal does. Read any figure as a rough guide, not a promise, and do not confuse a maker's warranty with the roof's likely life.

For comparison, Marley gives concrete tiles around 60 years, and notes this is no guarantee of how long a given roof lasts. A properly fixed tile roof is easy to repair later, one tile at a time. A metal roof can be harder to patch invisibly, and a dent or a damaged coating cannot be matched as easily as a replacement tile.

The price depends on the metal, the roof's shape, the build-up beneath it and access. Once the roof has been surveyed you receive one total in writing, supported by pictures of what we found. If you are comparing metal with tile, our clay tile roof cost answer and the guide to reusing roof tiles are good places to start, and the roof replacement page covers the wider job.