This is the original metric version of the plan (millimetres/centimetres). See also Garden shed plans : Imperial (feet/inches).
Our plan uses corrugated iron and clear corrugated PVC for the roof. However, you can use any kind of roofing iron and follow the basic guidelines in the plan for installing it.
If you can find iron sheets 1800mm long then this will make your life easier. Cutting one of these sheets in half will give you two 900mm lengths (the perfect size for this project).
Depending on the effective coverage of your sheets of iron, you will most likely need three lengths on each side to complete the roof. If you use transparent PVC for the center sheet, it will act like a skylight and let more light into the shed.
You can cut sheets of both iron and PVC to size if you need to.
We find the easiest way to cut sheets of corrugated iron is with an angle grinder. This will leave a tidier edge than tin snips, but do whatever you are comfortable with.
ideally the iron should turn up at each edge. This feature will minimise the chance of water seeping in around the edges of the roof.
Securing the roof
Use flat-head roofing nails to attach the roof. Pre-drill holes in the iron and only nail through the convex parts of the iron (the bits that stick up). If you nail into the concave grooves in the iron then water can seep through the nail holes. Drive the nails in just far enough to hold the roof down tight, but do not dent the iron if you can help it.
Position the sheets of iron so that the lower part of the roof overhangs the frame slightly. Water should be able to run off the roof and not find its way down into the shed (remember there needs to be room for cladding too).
If you have used 900mm lengths you will be left with a gap at the apex of the roof. A small gap does not matter as you will be capping the roof.
Cover the apex of the roof with metal flashing. You should be able to find materials designed for this purpose at your local hardware store.
Finishing touches for the roof
There are two ways to deal with the edge of the roof. You can bring the iron over the top of the bargeboard and secure it to the edge. However, on page four we suggested you install the bargeboards in a manner that will see them sit higher than the level of the roof.
Our preferred way to deal with the exposed edge of the iron is to cap the top of the bargeboards with lengths of 25mm by 50mm timber as shown in Figure 6.1. This method will cover the ends of the corrugated iron, and should stop water finding its way around the ends of the roof and into the shed.
For further protection against water you can use a silicon-based sealant along the edge where the roofing iron meets the bargeboard before you cover the end with timber.
You can buy small guttering at most hardware stores that can divert the water running off the roof to each end of the shed. However, this addition is not essential.