The factors to consider when designing the rooflight configuration
are:
- Is there sufficient general lighting to create a pleasant
and suitable internal environment?
- Is there a requirement for increased or controlled light
levels in specific areas of the building e.g. play area in
a sports hall?
- The relationship between the height of the building and
the diffusing quality of the rooflights to provide good general
light at ground level.
- Degree of roof maintenance and roof access envisaged.
- Weatherability and minimising laps, especially between
dissimilar materials.
There are a number of possible configurations for the rooflights.
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Chequerboard
Rooflights
This allows for individual rooflight units, both in
plane and out of plane, and provides the most uniform
distribution of light. The rooflight is fixed to the
metal cladding or roof deck on all four sides and is
therefore well supported.
This design has the maximum number of end laps or flashings
and therefore requires the maximum attention to the
sealing details by the roofing contactor with resultant
increased costs. |
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Ridge Lights – Barrel
Vault Rooflights
Using a barrel vault rooflight along the ridge can provide
an aesthetically pleasing design and a relatively uniform
distribution of light only if the roof slope is short.
The major advantage over the chequerboard arrangement
is that they reduce the number of metal/translucent
junctions to be fixed and sealed. However, at the ridge
they are subject to high wind loads. Since it is recommended
that rooflights should not be walked on at any time,
where roof access is expected and frequent, ridge lighting
provides a safer option. |
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Ridge to Eaves –
In Plane or Barrel Rooflights
Both profiled and barrel rooflights can be fixed from
ridge to eaves or from ridge downslope. They minimise
the number of metal/translucent junctions and could
eliminate rooflight end laps, thereby improving reliability
and servicing. However, since the rooflight industry
does not recommend walking on rooflights at any time,
a ridge to eaves layout will limit access across the
roof. |
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Mid Slope Rooflights
This configuration is only possible with rooflights
which match the roof profile. It provides a compromise
between chequerboard and ridge to eaves in terms of
light distribution and buildability. It avoids all areas
with high wind uplift and allows general roof access
if the metal roof is suitable for walking on. This design
is now very popular on new build work. |
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Continuous Run –
In Plane Rooflights
Good levels of lighting achieved but less used on modern
design. Care needs to be given to manufacturing and
fitting tolerances of the metal sheets and rooflights
to avoid a build up of tolerance difference.
Replacing old reinforced glass fixed in T bars with
modern profiled rooflights or panel systems is common
practice and very effective. |
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North Lights – In
Plane Rooflights
This configuration could be viewed as a continuous run
as above but is not subject to tolerance difference
between metal sheets and rooflights. North lights on
new build is no longer common practice but refurbishment
with modern rooflights or panel systems is easily achieved. |
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Random Design on Flat
Roofs – Barrel and Dome Rooflights
Used on flat or low pitch roofs, the rooflights are
placed according to need and roof design on purpose
designed upstands. |
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Curved Roof – Barrel
Vault Rooflights
Placed on an upstand that curves to the roof, barrel
vault rooflights can be applied to run over the crown
of the roof and stopping either mid slope or down to
the eaves. Ideal for metal standing seam system roofs
and single ply membranes. |
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Structural Glazing
Bespoke structures of almost any shape and design, normally
constructed from aluminium or steel sections and glazed
with polycarbonate or glass units of varying specifications.
These custom built structures are generally detailed
by the rooflight manufacturer to an architects brief
and allow immense freedom of design. |
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