Long skinny shapes (narrowest edge less than 1/2 the
length of the longest edge)
should always be avoided.
A cable to a remote attachment point may extend one
corner; otherwise the corners should be fixed directly to a post or an adequate
fixing point. Use of extending cables
allows the membrane to move too much which increases shock loading and reduces
membrane life expectancy.
Flat shapes such as triangles must be canted adequately to
keep them from "puddling" during rain. A slope of 1:4 is the
recommended minimum. But with larger
triangles or
flat sails more slope is even more imperative. Failure to have enough slope will cause
puddling and excessive sag which can cause a membrane to fail.
When possible, a twisted shaped is preferred such as a
hyperbolic parabola. This
imparts a 3rd dimension of tension into the membrane.
Another way to get this 3rd dimension is to have one corner of the
quadrilateral much higher then the other corners. (High Point Sail) Membranes with 3 dimensions and are not
relying on just edge tension, have a more even distribution of forces. Flat 2 dimensional sails tend to concentrate
forces at the corners and edges, A Shade Sail is only as strong as its weakest
point. Therefore, a flat 2 dimensional
sail is not as strong as a 3 dimensional form and will not last as long when
exposed to the same conditions.
Hyperbolic and “High Point” shaped sails should have
height difference that create a minimum 1:4 slope from high to low fixing
points. This is the minimum to start
getting the 3 dimensional effects.
Slopes of 1:2 are recommended and are also more
aesthetically pleasing
as well.
Sails should not be allowed to stay up in the event of
snow. Long-term loading will stretch
the fabric. Shade Sails do not shed
snow well.
Overlapping sails should
have a minimum of 18” of separation to avoid chafe. Movement in high winds can cause close sails to touch and they
will suffer chafe damage in a very short time.
When these rules are followed you can expect much less
movement of the Shade Sail
and therefore longer life.
It is the installer’s responsibility to understand and
follow these rules and recommendations. When these rules are not followed then
any warranty given or implied by Shade Sails LLC becomes void.