John over at Secrets of shedbuilding has kindly written a post about a leaking roof, in response to my problems with my shed roof, which know I think is the side wall letting in water, after the roof initially leaked!
Does your existing shed roof leak?
Want to decide which is the best roofing material for your new or existing shed roof? The traditional option for covering a shed roof in the UK is roofing felt. According to AnyWeather Roofing in the US, the popular choices are asphalt shingles, clay shingles, and wood shingles. Another option has become more popular in the past few years, had you considered using felt shingles?
Felt is a polyester reinforced bitumen coated sheet which normally has a protective fine green mineral finish. The traditional roll of roofing felt has a lot going for it as it is cheap it is quite easy to install. The main down side is its longevity. Even the suppliers say that standard shed felt is only good for 5 years. A roll of the thicker garage felt might last a bit longer say 10 years. The felt is also a single ply so if it gets broken or damaged it will start to leak. As soon as water starts to make its way into the shed it causes damage to the roof deck, it can cause mildew and allows the contents to become wet or damp.
An alternative to shed felt is felt shingles. These come in packs that cover about 3m² and are nailed down to the shed roof giving an appearance of roof tiles. The shingles come in a strip of three which makes it easier to get them all lined up properly. The shingles are designed to be pretty durable and with manufacturers claiming a life span of between 20 and 40 years, you shouldn’t have to replace them too often.
These three tab shingles are nailed down to the roof and overlap each other, so that you have a fish scale sort of effect and the roof is covered by at least two layers at any point. The shingles come in a variety of colours, most commonly green, brown, red and blue. Shingles also come in a variety of shapes, but these are normally to special order.
Shed felt comes in a roll and costs about £1 per square metre. Shingles come in packs that normally cover 3 m² and work out about £7/m². On material price per m² then shed felt is the cheapest by far.
However if you look further and consider the cost/m² per year then the difference is a lot less. With a life span of 5 years shed felt costs 20p/m²/year, felt shingles with a 25 year life span come in a lot closer at £0.28/m²/year.
When you price in your time for re-felting and repairing the roof every 5 years, the benefit of improved appearance with shingles and the reduced risk of water damage to the contents of your shed the shingles start to look a lot more attractive.
Installing roof shingles is quite straight forward, as you can see from the link.