The roof is covered is a variety of different materials starting with a simple lightweight roofing felt, through to decorative felt tiles, cedar shingles and slatted boards or Onduline roofing.
Roofing felt is determined by weight so you can get 8kg, 10kg and 20kg weights and the thicker the better. On the cheap sheds they go for the very lightest and thinnest felt, again because of cost. The better roofing felts will have a granule or mineral finish on the outside and this will help to protect the felt from the sun. The very minimum thickness of felt you should use on your garden shed or summerhouse is the 10kg weight with the ideal being 20kg.
Felt tiles are made from the same materials as normal roofing felt but would normally come in a range of colours. These tiles are supplied with a roof tile shape cut onto the lower edge of the felt so when it is fitted to your summerhouse it gives a very attractive appearance. The downside of this is that the felt tiles are more expensive than normal roofing felt and it is very time consuming to lay and this adds to the cost of your new garden building
Cedar shingles are made from cedar and are very long lasting. There would normally be a layer of roofing felt underneath as well which would ensure your garden shed or summerhouse would have an amazing long life. These cedar shingles over time will take on an attractive silvery appearance which looks quite stunning.
Slatted roofs would also have felt underneath to ensure the highest degree of water proofness. These boards would also normally be made from pressure treated timber to ensure a very long life and again it is the appearance which would encourage gardeners to have this option.
Onduline roofing is a superb option to normal felt on your garden shed or summerhouse. The Onduline is made from bitumen, the same as normal roofing felt but is a lot thicker, and it is made into a corrugated sheets. The thickness of the boards and the corrugation makes these type of garden shed or summerhouse roofs very long lasting. In fact much longer than standard roofing felt and would normally come with a 15 year guarantee.
These Onduline roofs don't even need a flat roof for the Onduline sheets to sit on. All that is needed is the normal internal roof supports. However, you will often find that the better garden building manufacturers will line the underside of the Onduline roof to ensure a aesthetically pleasing appearance inside your building.. It is also possible to have translucent roof panels in your but this option can be a little expensive..
Living or Green Roofs:- These are garden buildings covered completely or partially with plants and vegetation over an under layer of a waterproof membrane. You may also find extra layers to aid drainage, irrigation or as a root barrier. The colour of the roof is totally dependent on the plants or grasses used and your shed or out building can have an amazing amount of colour and create a haven for wildlife. The advantage of the green roof is that it helps with insulation in your garden building helping to keep it cooler during the summer months. But this type of roof does require a degree of maintenance and a stronger roof in the first place.
Generally speaking roofing felt is laid flat on the roof ensuring the upper layers overlap the lower layers so any water will drain away It is normally held in place by the use of galvanised clout head nails. These are nails which have a large round head so when the clout head nail go through the felt there is a large part of the nail holding the felt in place. Sometimes the felt on the garden shed will be stuck down using hot pitch and this is a very good as the strips of felt are effectively stuck together. The downside to this is that it is very time consuming and there for expensive.
You will find the cheap shed manufacturers will use felt which you can nearly see through and the reason for this is that they cut their materials costs right down to the bone. This felt will last a few years, if you lucky, and then you, quite often, will need to replace the felt. This is important to do because on the cheap sheds they use chipboard or OSB (sometimes referred to as wafer board or sterling board) board. on the shed roof and when it gets wet it will swell and disintegrate. This is sometimes just described as sheet material so be aware of this.
There is also a danger on sheds made with chipboard, OSB board or sheet material when clout head nails are used. If the nail is not aligned or put in straight it can leave a small gap for water to get into the board. If this happens then the boards will swell and that will be the start of the end of your shed roof.
You also need to consider the type of materials used to make the garden shed roof for long term peace of mind. You will find that quality garden shed and summerhouse manufacturers, 1st Choice Leisure Buildings, will use quality timber and building methods which will ensure a very long life for your building. At the other end of the scale you will find that unsuitable materials (for long term peace of mind) are used as the cheap sheds (read cheaply made) are made down to a price with the cheapest materials being used.