Clearview National October 2015 - Issue 167 | Page 64
ALUMINIUM
Do metal windows and
rooflights really cause
condensation?
Managing Director Lumen Rooflight, Paul Trace
talks to Clearview extensively about the cause
of condensation in metal windows and rooflights.
»»As the colder
weather is now upon us, it is
advisable to understand the causes
of condensation and how to
reduce its impact.
It is a fact that all metal
windows and rooflights are more
susceptible to condensation, but
this is not to be confused with
metal windows or roof lights
causing condensation.
Condensation occurs where
humid air comes into contact
with air, or a surface, which is at
a lower temperature. Air contains
water vapour and the warmer
the air, the greater is its capacity
for carrying water vapour. When
warm, moist air comes into
contact with a cooler surface, or
cooler air it drops in temperature
and loses some of its capacity for
storing moisture. Some of this is
released to form condensation in
the air as steam, or on the surface
as water droplets.
It is more common to observe
condensation on surfaces that
cannot absorb liquid, e.g.
windows, ceramic tiles, but it can
form on any surface and it may
not be noticeable until mould
appears, or the material starts to
rot.
Some examples of
where the water
vapour comes from:
Breathing: Two sleeping adults
produce one and half pints of
moisture in eight hours, which is
absorbed as water vapour into the
atmosphere.
Cooking: Steam clouds can be
seen near saucepans and kettles,
and then seem to disappear. The
clouds have been absorbed into
the atmosphere. The cooker itself
may be a source of water vapour;
e.g. an average gas cooker could
produce approximately one hand
half pints of moisture per hour.
Washing up: The vapour clouds
given off by hot water are rapidly
absorbed in the atmosphere.
Bathing, laundry, and wet
outer clothing: These are often
the major sources of water vapour
in the home.
Heaters: A flueless gas heater
can produce up to two - three
pint of moisture per hour. Paraffin
heaters produce nine pints of
moisture for every eight pints of
fuel burned.
Indoor Plants: A frequently
unrecognised but nevertheless
significant source of water
vapour.
New Property: The bricks,
timber, concrete and other
materials in an average three
bedroom house absorb about
1,500 gallons of water during
construction. Much of this
is dissipated into the indoor
atmosphere during the drying out
period.
64 » OCT 2015 » CL EARVI E W- UK . C O M
The best solution
for preventing
condensation is
ventilation, but
installing doubleglazing and thermally
insulated frames will
simply make the existing
moisture in the room less
apparent. In poorly ventilated
rooms and humid environments
such as kitchens and bathrooms,
condensation can condense on
cool steel skylight frames.
Of course, it is better that this
water vapour forms on the steel
frames, where it can do less harm,
rather than on internal wall
finishes.
Condensation forming on our
double glazed units is a good
indication that the moisture
content in the room is too high.
Lumen rooflights are supplied
with Pilkington Activ neutral,
argon gas cavities and Pilkington
Optitherm S3 double glazed
units. These provide a centre pane
measurement of 1.1.
If condensation does occur,
it is essential that it is wiped
away. Leaving moisture on the
metal frames and the American
ash linings will increase the risk
of damaging your rooflight.
The time to act is when you see
moisture and not when you see
mould growth on the liners.
Prevention is far less problematic
than curing issues that have been
left for weeks or months.
It is interesting to note that
every window manufacturer and
Housing
Association has now issued a
pamphlet about condensation,
and what can be done about
it. Interestingly, not one of
them says get rid of your metal
framed windows or rooflights the reason being - steel framed
windows and rooflights do
not cause condensation. The
download section on our site
includes a copy of the Glass &
Glazing Federation (GGF) guide
to condensation.
The Lumen range of
rooflights includes designs for
conservation and contemporary
projects for both pitched and
flat roof applications. Lumen
rooflights are manufactured to
an industry leading standard
and incorporate a wide range of
Pilkington glazing, including
self clean Activ.
Water vapour examples
extract from the GGF
Condensation Causes and
Advice Leaflet.
Visit www.lumenrooflight.co.uk,
call 0330 300 1090 or email
[email protected]