Builder’s Take: Flat roofs make a comeback, all is forgiven
From felt and PVC to zinc and copper, flat roof systems have come a long way and there are many options depending on your budget
A wise man once told me: “There are three certainties in life: death, taxes and a flat roof to leak.”
That’s a couple of decades ago now and thanks to product development it shouldn’t really be the case today. The man had a point though. We live in a wet climate that often has a fair breeze too. Ireland must have some of the best roofers in the world, as their work surely gets tested with that wind-driven rain.
Aaron Daly, from Dún Laoghaire-based Aaron Daly Roofing, says: “Flat roof systems have come a long way from the troublesome ‘pour and roll’ systems. Modern materials, design and ventilation have completely changed ‘flat roofing’.”
Flat roofs shouldn’t really be flat anyway. Even though joists go in level, firring pieces are used to give it a small fall, (about 1:60 or 1 degree), and direct water to an outlet or gutter.
Flat roofs are very popular on rear extensions, as first-floor windows often inhibit the use of an apex or lean-to roof. The trouble is, because of these very windows, the flat roof becomes a prominent feature in your life, often replacing what was a picturesque shot of your garden and manicured lawn. So how can we make it more pleasing on the eye, without going to the effort of a roof garden?
Torch-on felt is what covers most and they have come a long way. The go-to option, cheap and readily available, it generally goes on in two or three layers. They can either have a granular finish or a smooth finish which is then painted with a silver-coloured solar reflective paint. It usually comes with a materials guarantee of 10-15 years and costs about €55per sq m.
Another alternative is PVC. A single ply membrane of usually grey-coloured rubber is fixed to your timber base, thus making labour costs cheaper than the installation of a two-ply material. When laid well it looks smart, costs 20-30 per cent more than a torch-on system and will come with guarantees of around 12-15 years.
Then there’s fibreglass, where the jury still seems to be out. Its inflexible nature is not suitable for some situations, but advances in materials in recent years have made fibreglass roofing more reliable.
Whatever roofing material you choose, it is paramount to use experienced tradesmen
While it shouldn’t get the wooden spoon at the beauty pageant, it may not win it either. Costs are around €70 per sq m on domestic-sized roofs and should be covered for about 15-20 years.
Zinc is growing in popularity. One of my favourites, it’s a slick, smooth, contemporary look that goes on in panels with a standing seam joining each panel.
It is naturally resistant to corrosion, needs minimal to no maintenance due to its natural, self-protecting patina, and is extremely long lasting – 100 years-plus. It can come in a few grey, dark and silvery colours and will maintain its colour throughout its life.
Costs are about €120 per metre by the time up-stands, drips and fascias are taken into account. It is a nice advantage to be able to do your fascias, soffits and rainwater goods in the same material, giving nice continuity.
Copper is a more traditional way to go. It is one of the few metals that occur naturally rather than needing to be extracted from ore, thus making it one of the earliest metals to be used.
The covering of choice for well-to-do buildings of the past. The gorgeous green patina it develops after years of oxidation has long been coveted by architects.
A truly beautiful natural product but unfortunately it comes with a truly jawdropping price tag. Expect to pay in the region of €130 per metre. Like zinc, it is extremely long lasting, around 100 years in this country.
Lead, another beautiful and traditional product, is hugely malleable, and mostly used on small areas, over bay windows for example. Cost would be similar to copper at €130 per metre and comes with a material guarantee of 50 years.
Alkorplan is another option. It’s a PVC-based single ply membrane available in a variety of colours. It can look like zinc from a distance, with its standing seams, but will cost a good 30 per cent less.
Whatever roofing material you choose, it is paramount to use experienced tradesmen. Aaron Daly says: “The most important factor is the quality of the workmanship. Most failing roofs are due to poor installation. Roof systems should be installed by competent and approved contractors and always to the manufacturers’ instructions. All material guarantees are only valid if they have been installed correctly.”
Roof maintenance is often overlooked too, but can be a worthy exercise as it can make a huge difference to your roof’s performance and lifespan.
Kevin Moran is a builder – moranbuilders.ie