Insulate Magazine Issue 12 - November 2017

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The coldest recorded temperature in November last year
(UK)is -9.7°C and the hottest recorded day in 2016 (UK)
is 33.9°C.
The complete 48-hour cycle is
shown in the graph below:
These temperature changes can lead to a door leaf bowing
in its frame, which has an effect on the way it operates,
and in extreme circumstances it will allow draughts
to enter the home.
Choosing the right material can have an enormous
effect on the door’s performance. Different types of
insulation infill can influence how the door reacts to
changes in differential temperatures, so it’s important to
test the product before it goes on the market.
Test Services at the BBA has been using procedures
that have been devised to determine the effect of thermal
stress in the material build-up of doors, looking at
the infill medium, thickness of reinforcement or PVC-U
skin of a door leaf.
As you’d expect, this involves Summer time testing and
Winter time testing environments, to measure bow and
defection of a door leaf inside its frame at different internal
versus external temperature differentials.
This helps to determine permanent defection of the door
after extreme exposures, and to monitor any damage
like cracking or splitting for example. The effort required
to open and close the door, (operating forces),
are recorded before and after exposure to ensure all the
hardware functions correctly.
The sample will then be allowed to return to ambient
conditions before the operating forces are measured.
As you’ll have gathered, the testing is extremely thorough
with rigorous temperature applications applied in
carefully simulated, real life conditions. It’s important to
remember there’s a lot more to putting the wood in the
hole than meets the eye. The good news is properly tested
composite doors can contribute significantly to better
and more sustainable insulation in homes up and down
the country.
Something to celebrate this Christmas
The specimens are installed with their external face in
an environmental chamber that is set to cycle between
-10°C to +10°C. The internal face of the door leaf remains
in the test laboratory ambient conditions. At periods
of one hour during the positive temperature parts of
the cycle, a 30 second water spray will be applied to the
external face of the door.
During the test, the deflection of the internal face of the
door leaf is measured at the top and bottom corners of
the locking edge.
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