Canopies UK Managing Director Jason Eastwood says that specifiers need to beware of seemingly cost-effective off-the shelf options for canopies, and discusses the importance of site-specific calculations for bespoke fit-for-purpose solutions.
Research suggests that many leading canopy manufacturers apply surprisingly little engineering acumen to the design, build and installation of the canopies they supply to customers. This can result in maintenance and performance difficulties, additional remedial costs and poor aesthetics – all much sooner than anticipated.
With canopy suppliers aplenty offering fast installation on seemingly cost-effective ‘off the shelf’ product solutions however, specifying a walkway, entrance cover, or semi-permanent building extension can appear quick and easy.
But with product and installation quality, longevity and performance all of key of key importance in the specification of shelters which will offer a long service life, shouldn’t the canopy you choose be engineered specifically for the building you are designing?
Alarmingly, there are very few canopy manufacturers that currently engineer their products on a site-by-site basis, which means the product you choose most likely hasn’t been designed, manufactured or installed for the building it will be attached to, or the ground it will sit in.
Site specific calculations
To engineer a canopy for a specific project, your chosen manufacturing partner should conduct a comprehensive site survey consisting of a number of site specific calculations. These measurements will determine how your canopy should be both manufactured and installed in order to optimise performance, longevity and visual appearance.
Site specific calculations take into consideration factors such as wind speed and snow fall, pre-existing trees and roots, drains, sewage and terrain type. If the canopy is to be attached to a building, other factors include the age, strength, height and construction of the wall in question.
On the following page we will take a look at these considerations in more detail.
Battling the elements – wind speed and snow fall
It will come as no surprise to learn that coastal towns are subject to more wind than inner-city suburbs, and that the most northerly parts of the UK experience more snow than the Midlands. But did you know that there’s actually a myriad of variables at play when calculating wind speed and snow fall?
In addition to basic wind speed and snowfall measurements local topography, town terrain, site layout and altitude are just some of the additional which should be calculated when designing a canopy that will withstand the natural elements.
The footings of a typically canopy structure would sit around 800mm deep, but could go down as far as one metre if the shelter requires additional support due to high winds or other factors.
There are a number of below ground variables which can affect how a canopy should be erected in order for it to perform at its best throughout its warranty period and beyond. Here are two key points:
While many urban areas benefit from good solid ground with a healthy clay content, historic landfill sites for example don’t offer the same construction-perfect ground. Furthermore, rural ground can be loose and not conducive to standard footings, which is where alternative foundation structures such as pile and beam systems come into play.
Below ground obstructions
Drainage systems, pipes, cables and tree roots are just some of the obstacles site specific calculations will identify. By
positioning the vertical posts of the canopy in accordance with any pre-existing obstructions and using steel to reinforce the structure where necessary, it is possible to avoid expensive utility re-routing works.
Off the wall
For cantilevered, wall hung canopies, site specific calculations will determine whether the wall is strong enough to take the weight of the shelter. With specific tests designed to mimic the weight of a canopy, a trained surveyor can ascertain whether additional foundation supports will be required in order to
safeguard the canopy, the building and its users.
Canopies that are engineered for purpose often have longer and more comprehensive guarantees. Specifying bespoke built shelters needn’t cause unnecessary work for architects and designers if the right manufacturing partner is used.