Obviously, the sun moves as the day progresses, and the shade moves with it. So for effective coverage, the cloth needs to create shade that falls in the right place at the right time. It should also be the right size to protect from direct and indirect ultraviolet radiation (UVR), and be made of the right materials.
Have a look at the area you want covered and think about why you need shade – is it a kids' play area that needs all-day shade, or do you just want awning protection from the searing afternoon sun? Are there reflective surfaces nearby such as concrete paving or light-coloured walls that could reflect UVR into the shaded area?
Consider the time of day you'll use the space and how that might vary over a year – a cool spot in summer may become an Arctic shadowland in winter!
A triangle shaped sail will offer less shade than a square, but it’s more spatially flexible and can fit into smaller areas better. Plus, it has one less fixing point, so you can be a little more imaginative with it.
If you choose to go with a triangular shade sail but you’re still keen on significant protection, consider layering two triangles across one another for a statement look that’s functional too.
Make sure your selection complements your space. For example, if you’ve got an existing source of shade – like a veranda – consider attaching shade cloth for extended coverage.
All sails will have curves along the edges when pulled taut.
For example, a 4m x 4m square shade is measured from corner to corner, so it’s not an exact 4m square.
Think about how the sunlight is going to come from overhead, and the angle it will hit your sail.
Be aware of rainwater too, especially if you’re going for an all-weather sail: try to create an angle that slopes away to one side (over a garden if possible) so that rainwater doesn’t pool in the middle.
Lastly, consider using turnbuckles to provide additional tensioning ability and keep your sail tight. Sails can stretch and loosen up over time, but by getting in early you can keep yours firm and fresh.