When trees are not a possible shade option, built shade can
provide the sun protection needed. Built shade includes:
Portable structures such as umbrellas,
tents and shade sails
Permanent built structures such as gazebos,
pavilions, awnings, patio roofs and pergolas
No one
shade design will meet all needs and suits all situations. Careful planning
ensures that the best type of shade is to be used. Planning should include
assessment of:
Where shade is
needed
When shade is
needed
Duration of
expected use, permanent or temporary
What activities
will take place under the shade, i.e. the size of shade
Funds available
for providing shade
Built Shade Structures – Portable
and Permanent
Portable structures are
readily available off the shelf and easy to set up, take down and stored. They
are a quick and cost-effective way to add shade to a space that only needs shade
occasionally or for a short time, but they may not be effective in protection
from indirect UV radiation reflected off surfaces such as sand and concrete.
Portable structures include umbrellas and tents.
photo courtesy of Queensland Health,
Queensland Australia
Installed adjustable and/or demountable structures such as retractable awnings
to the side of your house or shade sails are practical and flexible, allowing
change of shade in relation to the sun at that time of day and at different
times of the year.
Permanent structures, which
provide a permanent shade solution, are built structures of different shapes and
sizes to accommodate more people, typically made up of a roof and supporting
posts.
They are
generally more expensive, but are usually sturdier and more durable, and can
withstand harsh weather conditions. Examples include pavilions, gazebos or
pergolas, which are attractive, practical and can be used in all seasons. Most
important of all, it can minimize the impact of indirect UV radiation.
Other
than the cost and ease of installation, considerations for built shade
structures should include:
Common
shading materials for built shade structures are timber shingles,
polycarbonate and fibreglass sheeting, knitted polythene or woven PVC shade
cloth, canvas or other tightly woven cloths. When choosing shading material,
it is important that the shading material have a UPF (ultraviolet protection
factor) of 15-50+, i.e. allowing only 6 to 2% of the UV radiation to pass
through or at least a 94% UV radiation protection.
UPF 15-24 (94 - 95.9%) Good
UPF 25-39 (96 - 97.4%) Very Good
UPF 40-50+ (97.5 - 98%+) Excellent
Two factors that can affect the UPF of fabric are weave and
colour. Fabrics that have a tighter weave will block more UV radiation. Darker
colours absorb more UV radiation and therefore provide better sun protection.
photo courtesy of Queensland
Health, Queensland Australia
Textile or coated fabric (canvas) can provide up to 99% UV radiation
protection or a UPF of 50, but is susceptible to breakdown due to UV radiation
exposure, therefore it often has a shorter life span than shade cloth.
Shade cloth gives only medium protection of about 90% against UV radiation.
Double knits may give higher protection. It is also porous and may let water
through.
Be
aware of safety concerns of the shade structure:
Does it conform to current building codes?
Are the support systems such as posts visible?
Are there any ropes that may pose a trip hazard?
Is it made of non-toxic materials if used for playgrounds and school areas?
Can water run off its roof to avoid water-related problems later?
Are steps taken to minimize vandalism by selecting sturdy materials, having
covers high away from reach, keeping the shade structure away from fences,
walls or trees that can be climbed, etc.?
Other
factors to consider are: maintenance requirements, waterproofing qualities,
environmental consequences, wind resistance and ability to withstand the
winter.
Built
Shade as a Shade Option
Considerations for Built Shade Structures