Why metal roofing is a good choice – and how to calculate how many sheets you need

Tuesday 30th June 2020

Why metal roofing is a good choice – and how to calculate how many sheets you need

Choosing a metal roof for your building can be a good investment because it is lightweight and long lasting - plus quick to install.

Steel roofing sheets are extremely weatherproof, able to withstand high winds, rain, snow and even fire.

They are also unaffected by the growth of fungus, moss, or mildew – and resistant to damage from wild animals and pests.

With a wide range of colour coatings to choose from they are becoming an increasingly popular choice for builders and DIY enthusiasts, having been used by professional roofers for many decades.

There are, however, a range of things to consider when ordering materials from your supplier – including how many sheets will be needed to complete the job.

Here is a run-down of questions to think about before putting in the order:

1. What type of roof do you have?

It might be apex roof or single slope (also known as mono pitch).

2. What are the measurements of the roof?

You will need to provide the length of the slope (including any overhang you want for your gutter – and don’t forget to include an allowance for any side cladding that you might be erecting if it is not already fitted). Then also the length of the building.

If you also need sheeting for the rest of the building, not just the roof, then you will need measurements from the ground up to the eaves and the ground up to the apex.

It is also useful to provide the angle of the roof, although this is not necessary for determining how many sheets are required.
 
3. How many sheets do you need?

One single sheet covers 1m, so that should be easy to remember. In fact, a sheet is just over 1m wide, but when it is overlapped by a single corrugation its coverage is exactly 1m. So, if your building is 6m long you will need six sheets. If it is 6.5m long, you will need seven.

4. What colour sheeting do you need?

The good news is that steel sheeting comes in up to 25 different standard colours, so there is plenty of choice.

5. Do you need to let light in?

For buildings that need to let in light, then you can also include rooflights. These will match up exactly to any steel sheet but are translucent. How many you need depends on the type and size of the building, but between 10-20 per cent of the total roof area is a good rule of thumb.

6. Are there other types of roof sheeting?

Fibre cement, bitumen, polycarbonate, PVC, and insulated metal roofing are other options.

The skill level of the fitter is important to consider. Cement roofs require a high level of skill to install, for instance, so metal sheeting can be a better option for many.

Metal sheeting is suitable for just about any commercial and industrial buildings as well as agricultural, equestrian and domestic outbuildings

7. Are there any other questions you should ask before deciding which roofing to use?

Relevant questions include whether your building is coastal (because a coastal roof may require a more durable coating), whether insulation is needed, whether you intend to keep livestock inside, whether you need to let light into the building and whether goods stored there could be sensitive to condensation (in this case your roof may require an anti-condensation finish).

8. Are there different qualities and prices when it comes to metal roofing?

Different thicknesses of sheet and different coatings are available depending on your budget.