Issue 44 winter 24 - Journal - Page 29
The elephant in the room
Paul Trace from Stella Rooflight discusses the practicalities involved in specifying large rooflights
in heritage properties
Heritage properties often feature thick walls, small
windows, and low ceilings-architectural elements that,
while charming, can result in dim and poorly lit interiors.
Historically, natural light was limited in these spaces, but
modern living demands more daylight to create brighter,
healthier, and more energy-efficient environments.
Bespoke conservation rooflights offer the perfect solution
to this problem. Designed to reflect the appearance of
original cast-iron rooflights, they blend harmoniously with
the traditional elements of a heritage building. With slim
sightlines and authentic detailing, these rooflights can be
custom-made to suit the specific requirements of each
property, ensuring they don’t detract from the building’s
character or historic value.
As a bespoke rooflight manufacturer we often see grand
plans with expansive areas of roof glazing, as architects
seek innovative ways in which to exploit natural daylight
in heritage properties. As much as bespoke rooflights can
certainly help bring these designs to life, there are some
important factors that need to be considered when the
glazing is turned from drawing to reality.
In recent years we have noticed a trend towards larger
rooflights, with sizes regularly exceeding 2500mm in
width, height or both. While Stella can certainly accommodate these, one has to appreciate the practicalities of
weight, transportation and cost.
It stands to reason that the larger the rooflight, the
thicker the glass will need to be, therefore as rooflight
sizes get bigger their weight can increase exponentially.
In context, our double glazed units comprising of 4mm
thick glass weigh 20kgs per square metre and those using
6mm are 30kgs per square metre.Triple glazed units are
30kgs and 45kgs respectively. Add the stainless steel
frames and hardwood liners into the equation and you
can start to see how even a modest sized rooflight can
weigh something akin to a small elephant! Indeed it’s not
uncommon for us to produce rooflights weighing in
excess of 200kg.
The reality is that when you scale things up even the
simplest plans can start to become complex -a truth
that should be all too familiar to architects. But before
drawing that large rectangle on a roof plan, it is important to consider how the rooflight is going to be lifted
from the ground to roof level and what the weight implications might be for the structure.Stella can weld
stainless eyelets to the rooflight frame to aid the lifting
process and we would suggest doing this on frames which
weigh in excess of 100kg, which is the point where we
expect a crane might be required. However, does the site
have suitable access for any specialist lifting equipment,
and has this additional cost been budgeted for?
Below, Shore Road
