Frequently asked
Questions (FAQ’s)
How
have I got condensation inside my double glazed unit?
Condensation in the home
Looking after your
handles and hinges
Any advice on
cleaning windows?
How do the
‘professionals’ clean windows?
How can I clean my
upvc frames?
Problems with
lead?
How have I got
condensation inside my double glazed unit?
The double glazed unit
consists of 2 pieces of glass held apart around the edge by a (usually
silver coloured) spacer bar. This bar is filled with a desiccant, tiny
silica balls similar to those found in parcels to reduce the moisture
levels. In the case of double glazed units, the silica soaks up any
residual moisture held in the space within the unit when it is first
made. Around the outside of this metal spacer bar, sealant is pumped
to seal the unit and complete the process.
After a period of time
the seal 'breaks down', causing a hairline fracture in the seal,
thereby letting air containing moisture in. Various factors can
accelerate this breakdown, such as wood frames and putty, poor
frame drainage, poor installations not leaving sufficient gap between the
glass edge and the frame, locations in extreme sunny positions
or where excessive vibrations occur.
Once air can get into
the unit, the silica originally used becomes fully saturated and
condensation starts to form as temperatures rise and fall against the
side of the glass.
If your units were
installed during the last 10 years, check your guarantee and see if
you are still covered.
Despite rumours to the
contrary, it is not possible to repair the units by splitting them and
re-sealing them!
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Condensation in the home
Introduction
Condensation is an
extremely underestimated cause of damage to our homes. It is
responsible for rot in rafters, joists and wooden window frames; it
can cause mould and fungal growth on walls and ceilings and if not
dealt with, can damage our health.
Air in the home is actually a mixture of air
and invisible water vapour. The average family produces 10 to 50
litres of moisture a day from activities like cooking, bathing,
washing dishes, and doing laundry. Condensation is the conversion of
the water vapour into a liquid and usually happens when the vapour
cools. All air contains water vapour. The quantity contained
depends on the temperature of the air. This ratio is called the
relative humidity. Hot air is able to carry much more moisture than
cold air, so as the temperature of air rises, in broad terms, it
expands and attracts a greater volume of vapour.
The temperature at which the vapour begins
to condense is called the dew point. Condensation occurs whenever
warm, moist air comes in contact with a surface or object cold enough
to chill the moisture in the air below its dew point.
Outside, if this happens near
the ground to a small layer of air, dew or frost will be formed, if a
larger amount of air is involved, mist or fog will arise. If this
happens to air that is rising in the atmosphere and expanding clouds
will form
If it happens in the
home....It's called condensation
As soon as warm air,
containing vapour, hits a cooler surface, it will condense. This is
most obvious on windows and wall tiles, but it is happening on the
walls and ceilings a lot of the time. The common assumption is that if
we insulate ourselves and warm the house thoroughly, then this should
not happen...But it will, the air temperature will rise until it finds
a cooler surface unless we let that air out and some cooler air in,
which brings us on to ventilation.
Ventilation is the
answer to condensation. There are many ways we can deal with symptoms
or effects of condensation, but only one way to deal with the cause.
We must ensure the home is adequately ventilated.
Ways to deal with
condensation
Walls and other
surfaces can be wiped down regularly.
While drying clothes indoors, ventilate the room.
When people come in with wet coats, hang
them outside the living area to dry. A good reason for a porch.
Keep the kitchen door
closed when cooking, and open the windows.
After a bath or shower, try to ventilate
the room to the outside, not to the rest of the house - just opening a
window (and closing the door) will help.
Open all windows at
least once a day. Change all of the air in the house.
If security permits,
leave top windows in the bedrooms open, especially at night, when the
outside temperature drops and the indoor temperature rises as the
heating kicks in. Breathing is a major contributor to condensation!
Reduce the number of
indoor house plants, as plants increase humidity levels
If condensation is
excessive, try a dehumidifier to remove excess humidity from the air
What causes
condensation on windows?
Whenever there is
excess humidity in the home, it will manifest itself on the coldest
area of a wall, which is normally the window. The warmer the air, the
more moisture it will retain, so when it comes in contact with the
colder glass surface and the air is subsequently cooled, moisture is
released in the form of condensation.
Do windows cause
condensation?
No, condensation
on windows is not the fault of the window, unless the window seal has
failed and the moisture is in between the two sheets of glass.
However, by replacing drafty windows or even installing a new roof,
you are reducing air flow in your home and making it tighter.
Tighter homes retain more humidity.
Windows present a
difficult problem and years ago there used to be only one practical
means of dealing with the traditional single glazed domestic window.
This usually took the form of collecting the water forming in a
channel at the bottom of the window and leading it via 'weep holes' to
the external face. These 'weep-holes' or condensation outlets are
small holes about 1/4" in diameter drilled at an angle through the
frame so that water will pass by normal gravitation to the outside.
The easy answer
these days to alleviate window condensation is with sealed
double-glazing, and normally with PVC-U frames. The insulation
properties of both framework and glass is improving all the time as
technology moves on, and as measures are introduced by government to
improve energy efficiency in line with the Kyoto Protocol. However,
glass is still glass, and no matter how well insulated by
double-glazing, the interior pane will always be susceptible to the
formation of condensation in a situation where the relative humidity
reaches impossible limits. With double glazing, houses have become
more effectively sealed, keeping any moisture produced within the
house and providing better conditions for condensation to
occur, therefore ventilation has become highly important.
It is unlikely that a
home in the UK can be condensation free, however by keeping your
property properly maintained and thinking about your lifestyle and
decoration, you should be able to live with condensation without it
ruining your life.
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Looking after your handles and hinges
As with most moving
parts, a little 'TLC' on your handles and hinges will reduce the need
for repairs and increase the life of the item.
The hinges should be
kept free of dust and dirt - use a small brush or blow the tracks to
clear any deposits. After clearing the tracks, a light lubrication
with machine oil once a year in the spring will revitalise the hinge.
If this makes the hinge too loose, the brass friction screw located in
the arms of the hinge can be turned a half turn at a time to either
loosen or tighten the hinge. Useful if you have been finding the
window swinging right out and you can't reach the handle to pull it
back in!
By keeping the hinges
lubricated, less pressure is then put on the handle when the window is
opened or closed which in turn will help to keep the hinge from
breaking or snapping off. Again a little lubrication on the moving
parts should be part of your annual maintenance.
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Any advice on cleaning windows?
Clean windows with a
solution of 1/2 cup white vinegar to a bucket of warm water. If
necessary, dust off the window and sill with a clean paintbrush.
Don't clean windows
while they are in direct sunlight. Your cleaning solution will dry too
fast. Too hot of a day will cause windows to streak. This is the best
time to vacuum the frames and sills. Cool, clear water is the choice
of most professional window washers. For drying windows, a wad of
crumpled newspaper works just as well as expensive paper towels. Wear
rubber gloves to keep your hands free of ink. Shine windows with a
newspaper. It's cheap and easy. For a really fine shine, after the
windows are dry, rub a clean blackboard eraser over them.
Dry windows outside in
one direction and inside in the other direction. If you see a streak,
you will know if it is inside or out.
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How do the ‘professionals’ clean windows?
Have you ever
wondered how those professional window washers move so fast with the
squeegee, and the windows turn out perfect? Well, there really are
some tricks to it that are simple to learn, and once you do, you may
even enjoy washing windows. It is possible!
The first
trick is to invest in a good squeegee. They aren't expensive and they
are worth every penny! A professional squeegee has a very soft, rubber
blade with no imperfections in it. You can also get extra rubber
blades and simply replace that when it wears out.
Secondly, do
your windows on a cool or cloudy day. If you HAVE to do it in the sun,
do it in the morning. What you want to avoid here is heat. Heat works
against you.
Get a bucket
of lukewarm home made window cleaner as outlined above. Use a sponge
that has a white scrubber on the other side (don't use the green ones,
they are too course). Wet your window with the sponge side, then flip
to the white scrub pad side, and scrub the window. You'll be able to
"feel" when it's clean. You'll feel rough patches, etc when it's still
not clean. This is a step most people fail at, if the window simply
isn't clean, it's going to look cloudy when done. Scrub well.
You'll also
need lots of clean, white cotton rags, towels or cleaning cloths. Dry
by hand a 1 inch strip at the top of the window. The trick for no
streaks with the squeegee is placing the dry rubber blade on a dry
window.
Take the
squeegee now and place it at the top of the window in that 1 inch dry
strip. Pull down smoothly. Dry your squeegee blade with between each
sweep. Finish window, if need be do one last sweep left to right at
the bottom of the window.
Take a dry, clean cloth and run with your
finger down each window side and across the bottom to clean and dry
the edges. They should look perfect! And you'll feel great having
clean windows.
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How can I clean my upvc frames?
Always be wary
before staring out to clean your Upvc frames. Practise first on a
small section before launching yourself at the entire house. Bear in
mind that they could end up looking worse than when you started. Initially the
frames may appear to be reasonably clean with a few marks but after
applying a cleaner, the Upvc will in general brighten up but make the
marks stand out more if they won't budge. Also don't forget to
consider the 1st floor frames if ladders are not your forte, you could
end up with nice clean frames on just the ground floor.
Some of the larger out of town DIY stores
now stock their own brand of Upvc cleaners and are well worth a try.
In the main these are non-abrasive and require a fair amount of elbow
grease.
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Problems with lead
As with all lead
products i.e. lead sheet, pipes, flashings, etc., the adhesive lead
strips, which we use for our sealed units, are subject to oxidation.
This ‘weathering’ process will form a naturally protective patina when
exposed to the atmosphere.
This patina is a
layer of highly insoluble lead salts, which gradually form on the lead
surface to eventually give the familiar grey lead appearance. Examples
of this effect can be seen on old leaded lights, such as in church
windows.
During the initial
stages of the oxidation process, lead can display various colours
including blue, bronze and green. It is probable that such films are
extremely thin and in fact have no intrinsic colour but appear
coloured due to an interference effect Similar interference colours
may be observed when oil is present on a wet road. Lead is most likely
to appear coloured when placed indoors or in protected locations.
When lead comes
into contact with moisture, rainwater, condensation etc., at early
stage, discoloration, spotting and white powdery deposits (usually
basic lead carbonate) can form and may ‘run-off’. The degree to which
all these occur is governed by the environmental conditions, but with
longer term weathering, the lead will take on its’ familiar
appearance.
Investigations
have shown that the patina formation follows the route: lead, lead
oxide, basic lead carbonate, normal lead sulphite, and normal lead
sulphate. The ‘run-off’ stage occurs when non-adherent basic lead
carbonate is formed, usually through contact with moisture. Each of
the stages in patina formation is adherent, highly insoluble lead
salts and in practice, as these salts develop with weathering, they
stifle the basic lead carbonate release. The final patina being
approximately 30% normal lead sulphite, 60% normal lead sulphate and
10% normal lead carbonate. However, this can vary dependant upon
location, time and airborne impurities.
Suggested after
care
In the event that
you experience an accelerated rate of oxidation directly after
installation, you should make every effort to clean the ‘run-off’
deposits, as soon as possible. Failure to do so could result in the
deposits drying onto the glass and becoming more difficult to clean.
This effect can be compared to lime scale on a shower screen.
To clean the
glass, simply use a water-based glass cleaner with a paper or cloth
towel, whilst removing any stubborn stains with a household
non-abrasive cream cleaner. Avoid agitating the surface of the lead,
as much as possible, as this will slow down the weathering process.
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