Light? Shade? Shelter?
This is probably one of the most fundamental questions that you need to ask yourself when considering an external outdoor covered area. Getting it right is important so that the best use of the area can be achieved for the maximum amount of time.
In the UK and Ireland we have a variable climate as we all know, so unless your challenge is only to shade a south facing elevation then the answer to, Light? Shade? Or shelter? is probably that you want to do all three at various times. Therefore, you may need to consider an external roof that can deliver all three of these outcomes.
There are a large number of various options ranging from awnings and umbrellas through to adjustable roofs which slide, retract or open and close.
Some give more flexibility than others and the use of one type over any other will often be dictated by the structure, what space is available or by any adjoining buildings if the external area is going to be adjacent to an existing building.
A sliding roof will give a good deal of flexibility if you have height and space to accommodate one. If so the decision will be whether to make it with a solid (non-transparent) material that will allow some opaque or diffused light through or to make it with a translucent material. Something likes an opaque polycarbonate or a translucent polycarbonate.
The critical thing to remember with sliding roofs is that the sliding panels need to stack at one or both ends of the roof and this can have height implications. Also unless it is possible to stack the sliding roof panels outside the roof area by building an overhang then some of the roof area will always be obscured where the roof panels are stacked. Some 25% to 40% of the roof area may be taken up by the need to store/stack the sliding panels within the roof area which can significantly reduce the amount of clear roof area that is available. The trade-off is always between the size (and therefore the number) of sliding panels needed to cover the area of roof and the height of the stack of panels at one or both ends of the roof when it is open.
A louvred roof is another way of delivering light, shade and shelter over an outside area. Again a decision needs to be made as whether solid louvres (aluminium) are used to give maximum shade or translucent or opaque polycarbonate louvres to allow light through all the time.
There are two types of louvre roofs, those that support the louvres and operating mechanisms on beams across the roof and those that support the louvres at each end. The main difference is the spanning capabilities.
Where a roof is made using louvre beams to support the shading and weatherproofing louvres then the width of the area to be spanned is not an issue as more louvre beams can be introduced across the width or depth of the roof to support the louvres. This is particularly important with regard to meeting the UK and Ireland wind and snow loading requirements. The UK and Ireland have some of the highest wind speeds and combined snow loadings in Europe so this is an important issue.
On a roof where the louvres are supported only at each side by spigots attached to the opening/closing mechanism then the span available is limited because of wind and snow loadings on the roof. We would not use this type of construction for roof widths of more than 3 metres and would not advise our customers in areas where moderate to heavy snow fall occurs to use this type of opening and closing louvre roof.
Where a flat or barrel vault polycarbonate or GRP roof covering is going to be installed we would always recommend using steel support channels rather than aluminium ones as steel is stronger and can accommodate larger spans while meeting wind and snow loading regulations.
Contact us if you would like to know more about maximising the amount of light, shade or shelter for your external roof project. We can also direct you to useful sources of information regarding wind and snow loadings across the UK and Ireland.