Homeowner window information: answers to your frequently asked questions from our window experts.
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Concord  905-738-1870

Window Maintenance:

How do I clean window frames?
How do I clean glass?
How do I clean sash tracks?
How do I clean and lubricate hardware and screens?

Troubleshooting Vinyl Windows:

Why do my windows leak?
Is this normal?What is condensation?
What is "window sweating"?
Do windows cause condensation?
Is condensation bad?
Where on a window does condensation normally form and why?
Can I reduce the condensation on my windows?
What causes condensation on windows?
So how can I reduce condensation?
Will the use of Low-e, argon and warm edge spacers help in reducing condensation?

Technical Questions:

What is argon gas?
What are warm edge spacers?
Is it worth spending extra money on Low-e, argon gas and warm edge spacers?
What are the advantages of Low-e, argon and warm edge spacers?
What is energy loss? How does it occur? What can I do to reduce it?
What is solar radiation and ultraviolet (UV) rays?

Glass Related Questions:

What is Low-e glass?
What is tempered glass?
What is laminated glass?
Will using tempered and/or laminated glass make my windows unbreakable?


How do I clean window frames?> top

As a general rule, all parts exposed when the window is closed should be washed down with warm soapy water (mild detergent) or a plastic cleaner. Use a soft cloth, sponge or towel to avoid scratching. Rinse well with water.The exterior surface of window frames and doors may collect a layer of dirt over time, depending on environmental conditions. Rainfall will usually be sufficient to remove accumulated dirt. However in conditions with smog, excess smoke or dirt the exterior surfaces should be cleaned more regularly. A soft bristle brush or low-pressure spray cleaner may also be used .Avoid using high powered washers, ammonia, abrasive cleaning agents, glass cleaners and tile cleaners. Using these products over time will cause cracks.The pigments that are used in paint are almost identical to those used in vinyl, but vinyl's color goes all the way through. A little rubdown with Soft Scrub will bring vinyl back to its original brilliance.

How do I clean glass? > top

Glass is a durable material when exposed to normal atmospheric conditions, but it does suffer some surface deterioration. One of the most aggressive elements in the atmosphere is water. An absorbed layer of water attacks the surface of glass, dissolving or releasing certain elements that cause the water to become alkaline. With repeated wetting and drying without washing, the dissolved products will appear as a whitish scum. This reduces the brilliance of the surface and in severe conditions can obscure visibility. This latter condition is common where condensation is permitted to occur regularly. Consequently, frequent cleaning is important.

Glass can be cleaned with warm soapy water, vinegar-based cleaners or any cleaning product specifically formulated for the cleaning of glass. Avoid using ammonia or alcohol-based cleaners, which can cause streaking. Care should be taken not to damage glazing, frame finish, or insulating unit seals by overgenerous application of cleaners.Wipe the cleaning solutions on the glass in a circular motion, applying light to moderate pressure. If streaks appear, rinse the surface with clean water. Using a clean, lint-free cloth, wipe dry the interior glazing surfaces, including any interior frame or hardware components to prevent spotting or water damage.

To clean grease, oil, tape adhesive, crayons or paint, apply a small amount of acetone (mineral spirits) to a cloth or towel and rub only the affected area. Repeat the cleaning steps listed above, if necessary .Glass should be cleaned by starting at the top and systematically working down. This technique reduces the possibility of residue and cleaning solution rundown. Caution: Do not clean glass or frames while they are exposed to direct sunlight. Detergents and soap based cleaners may dry prematurely and leave a hard to remove residue on the frame or glass surface.

How do I clean sash tracks? > top

Parts exposed when the window is open should be simply wiped clean, removing grime from old lubricant, airborne debris, remains of insect life, etc. Special attention should be paid to keep the drainage channels free and clear of blockages.Sash tracks should be kept free of dirt by using a small brush and blowing the dust out of the tracks and corners. Keep moving the sashes so that different areas can be cleaned.Use mild soap or detergent to clean all tracks and sash cavities. This will allow the sash to operate smoothly and prevent excessive wear on hinges, locks, rollers and weather stripping components.

How do I clean and lubricate hardware and screens? > top

Remove all dust and grit before lubricating pivot points and all other moving metal parts with light machine oil. This should been done annually. A very light application of petroleum jelly or equivalent will keep the locking mechanisms and hinges in good working condition. A resin free grease or lubricant should be used on sliding bars, gears and face plates.In the case of sliders or single hung windows, a silicone spray (candle wax / furniture polish) can be used to help lubricate the sashes to help them to slide more smoothly.In the case of double hung windows a few drops of light machine oil or spray such as WD-40 applied via the top end of the balance tube will improve the operation of the balance.

Follow exterior surface cleaning instructions for all exterior screens. Interior mounted screens can be vacuumed with a soft brush attachment or wiped with a soap water solution. An easy way to clean screens is to remove them and lay them on a flat surface. Apply cleaning solution to the screens and let them soak for a minute. Then rinse the screens using a low-pressure spray. Alternatively vacuum with a soft brush.We would like to stress that at all times care should be taken not to overreach or risk falling.

Why do my windows leak? Is this normal? > top

Any operating window, either horizontal or vertical slider, will leak air and water. This is called air and water infiltration. Water infiltration is more visible. Windows are constructed with weep holes allowing any internal water to weep to the exterior of the home. Depending on weather conditions it is normal to see water in the sill section of windows.

What is condensation? > top

Excess humidity manifesting itself in the form of a thin film of water on a cold surface is called condensation. This is illustrated on a humid, hot summer day when condensation appears on a cold glass. If the temperature changes but no water vapor is added or taken away, then the relative humidity will also change and will increase as the temperature falls. The relative humidity will continue to rise with falling temperature until the dew-point is reached - that is, the temperature at which the relative humidity becomes 100 percent. Any further decrease in temperature will force some of the vapour to condense as water (when the temperature is above freezing) or as frost (when the temperature is below freezing). Condensation is the primary reason for window-related callbacks.

What is "window sweating"? > top

Condensation usually occurs first on windows because they have the lowest temperature of any of the interior surfaces in the house. This is commonly referred to as "window sweating". It seldom appears on walls because they are normally warmer. In extreme cases this has led to mildew and the growth of mould.

Do windows cause condensation? > top

No, condensation on windows is not the fault of the window. However, by replacing old drafty windows or installing a new roof, you are reducing air-flow in your home and making it more air tight. Tighter homes actually retain more humidity.

Is condensation bad? > top

The occupants of a house rightly feel that condensation on the inside surfaces of windows is not good. It not only creates a nuisance by limiting visibility and by wetting adjacent walls and floor surfaces, but in more severe cases it can cause the rotting of wood and the deterioration of paint and plaster. To the builder the problem takes on a special significance because the homeowner frequently assumes that window construction or installation is faulty. He does not readily appreciate that his own living habits are of prime importance, or that a well built house is often more vulnerable to excess moisture problems than one that is loosely constructed.

Where on a window does condensation normally form? Why? > top

Condensation often forms at the meeting rail and at the bottom of the lower sash on the interior of the glass. This is because when warm air cools, it falls down across the interior surface of the window at the same time that the air's temperature is falling. The air contacts the horizontal surface of the meeting rail, which acts like a dam, slowing the air's rate of fall and creating the perfect opportunity for the trapped water vapor to escape and form on the meeting rail's surface. The air then rolls over the edge of the meeting rail and again gains speed until it encounters the lower handle of the sash. At this point, the water vapour again makes its exit and lies at the bottom of the sash.

Can I reduce the condensation on my windows? > top

Yes. In order to reduce condensation, humidity must be controlled and air movement must be generated. As the exterior temperature drops, the humidity level needs to be decreased. Fortunately, the occupant can control window condensation, once they understand the causes.

What causes condensation on windows? > top

There are several factors that put moisture into the air and cause condensation on windows. Normal breathing and perspiration add 3 pints of water to the air every day for each person in your home. In fact, every activity that uses water adds more moisture to the air including cooking, taking showers, dish washing, and doing laundry. If you have too much moisture in your home, then look for some of these occurrences:

  • Constantly dripping faucets.
  • Any containers in the home that have water standing often or all the time such as sinks and pet bowls and open fish tanks.
  • Indoor drying of clothing and leaking indoor clothes dryers
  • Gas cooking. Moisture is a by-product of gas combustion.
  • Keeping lids open on toilets thus allowing more evaporation.
  • Not running the exhaust fan during baths and showers to remove the moisture.
  • Excessive use of things like steamers, plant misters or tea pots.
  • Some building slabs may not have a vapour barrier. You may see sweating on the slab where visible.
  • Overuse of humidifiers.
  • Faulty plumbing such as leaks in walls or under cabinets.
  • Leaking hot water heaters or water piping.
  • Excessive indoor plant containers that require watering.
  • Saunas and hot tubs.
  • Outdoor drainage that holds water against slab or bricks. You may need to inspect your sprinkler system, too.
  • Faulty shower piping or faucets and seals leaking into walls, etc.
  • Faulty refrigerators or ice machines that leak or drain excess water or moisture.
  • Poor ventilation in bathrooms.
  • Air conditioning.
  • Making sure the doors are not so tight as to not allow circulation of air from the room.
  • Extensive soaking of clothing in open water containers. You may wish to move these to the garage or utility areas.
  • Wet clothing, wash rags or towels repeatedly left laying out.
  • Rainwater leaking into the attic and/or walls.
  • Use of open space gas heaters especially at high room temperatures.
  • Poor refrigeration or faulty condition of the cooling system that doesn't remove enough moisture from the air. Have this checked by a technician.

  • Leaving floors very wet after mopping

So how can I reduce condensation? > top

Reduce the humidity and decrease the number of cool surfaces in your home. Your first step is to find what the humidity level in your home is. This will need to be monitored regularly as the temperature outside varies. Devices which measure humidity are called hygrometers. They can be purchased at most reliable hardware and home center stores. As a guide, the following chart will help:

Outside Temperature F°   Inside Humidity
20 F to 40 F   Not over 40%
10 F to 20 F   Not over 35%
0 F to 10 F   Not over 30%
-10 F to 0 F   Not over 25%
-20 F to –10 F   Not over 20%

Will the use of Low-e, argon and warm edge spacers
help in reducing condensation? > top

Yes! Choosing a window with low-e glass, argon gas filling and warm edge spacers will help to reduce condensation. However, it will not completely eliminate it.

What is Argon gas? > top

An odorless, colorless, tasteless, invisible, non-toxic gas used to replace the air inside the sealed units to reduce thermal transfer. It is six times heavier than air. Since argon gas is denser than air and is not in continuous motion like air, the transference of energy (heat and cold) is greatly reduced. In short, argon gas provides extra insulation.

What are warm edge spacer bars? > top

We often see condensation and even frost on windows, typically around the edges of window glass. The edge is where the panes of the sealed units are held apart by highly conductive aluminum spacer bars. Condensation is the primary reason for window-related callbacks. Non-conductive warm edge spacers reduce transmission of heat and the chance of condensation forming.The material the spacer is made from affects the rate that heat travels through a window's edge. Warm edge spacers can improve the U-value of a window by 10% and boost the edge temperature by around 5°F, thereby reducing condensation.

Is it worth spending extra money on low-e,
argon gas and warm edge spacers? > top

Low-e glass improves the insulating value of a window roughly as much as adding an additional pane of glass does. Low-e glass combined with argon gas boosts energy efficiency by nearly 100% over clear glass. Like all gases, argon gas will leak from the window over time. However, it is non-toxic and safe. Studies suggest a 10% loss over the course of 20 years, but that will reduce the U-value of the window by only a few percent. The added cost for low-e glass and argon gas fillings is only about 10% of the window's overall cost. It's a no-brainer.

What are the advantages of low-e, argon and warm edge spacers? > top

The main advantages are:

  • Reduced energy loss (heat and cold)
  • Reduced harmful ultraviolet (UV) rays
  • Environmentally friendly.

What is energy loss? How does it occur? What can I do to reduce it? > top

Windows are thermal holes. An average home loses approximately 30% of its energy (heat or air-conditioning) through them. Energy-efficient windows save money. The additional amount spent for a good energy-efficient window will pay for itself in two to four years. More durable windows cost less in the long run and make you more comfortable for as long as you live with them.

The heat loss of windows is measured using U-values or U-factors. U-values are the mathematical inverse of R-values. So an R-value of 2 equals a U-value of 1/2, or 0.5. Unlike R-values, lower U-value indicates higher insulating value. Windows lose and gain heat by:

Conduction
Transmission of energy (heat and cold) through a solid material through direct contact. The lower the conductivity, the lower the heat loss and vice versa. Double glazed windows filled with argon gas with warm edge spacers greatly contribute toward reducing conduction.

Convection
In a cold climate, heated indoor air rubs against the interior surface of window glass, which causes air to cool, become dense and drop downward. As the stream of air drops, warm air rushes in to take its place at the glass surface. This cyclical movement of air forms a convective loop and is self-perpetuating. Double glazed windows filled with argon gas with warm edge spacers raise inboard glass temperatures, thereby slowing down the convection cycle and improving comfort.

Radiant transfer
Movement of heat from a warmer body to a cooler body. Clear glass absorbs heat and redirects it outdoors. Radiant-heat loss through windows can be greatly reduced by choosing low-e glass that reflects specific wavelengths of energy. In the same way, low-e coatings keep the summer heat out.

Air leakage
Air leakage through windows is responsible for most of a window’s heat loss. This is commonly referred to as air and water infiltration. Well-designed windows have durable weather stripping and high-quality closing devices that effectively block air and water leakage. Hinged windows such as casements and awnings clamp more tightly against weather stripping than do double-hung windows, but the difference is slight. How well the individual pieces of the window unit are joined together also affects air leakage. Glass-to-frame, frame-to-frame and sash-to-frame connections must be tight.

What is solar radiation and ultraviolet (UV) rays? > top

Less than half of the sun's energy is visible. Longer wavelengths beyond the red part of the visible spectrum are infrared, which is felt as heat. Shorter wavelengths, beyond purple, are ultraviolet (UV). When the sun's energy strikes a window, visible light, heat and UV rays are reflected, absorbed or transmitted into the house. Low-e glass contains transparent metallic oxides that reflect up to 90% of the harmful UV rays.

What is Low-e glass? > top

Low-emissivity (Low-e) coatings are microscopically thin, virtually invisible, metal or metallic oxide layers deposited on the glass surface to reduce the U-factor by suppressing the radiant transfer of energy (heat and cold). Low-e glass for larger openings can reduce energy costs up to 25%. read more about low-e-glass

What is tempered glass? > top

Glass with a surface compression of not less than 10,000 psi or an edge compression of not less than 9,700 psi. Tempered glass is extremely strong and is used to reduce the risk of an accident or break-in. Fully tempered glass, supplied as standard with our patio doors, garden and French doors is four to five times stronger than ordinary float glass. Should the glass break, it falls out of the frame and is shattered into small pebble-like harmless pieces without sharp edges. This is by design and is proof of a well tempered product, not of a defective product. It is this fail-safe characteristic of tempered glass that makes it an excellent product for safety glazing applications.

What is laminated glass? > top

Laminated glass is a combination of two or more glass sheets with one or more inter-layers of plastic (PVB) or resin. In case of breakage, the interlayer holds the fragments together and continues to provide resistance to the passage of persons or objects. This glass is particularly suitable where it is important to ensure the resistance of the whole sheet after breakage. Laminated glass is also highly effective in reducing noise levels and has the ability to block 99% of the sun's harmful UV Rays.

Will using tempered and/or laminated glass
make my windows unbreakable? > top

There are misconceptions that tempered and laminated glass are "unbreakable" or "nearly unbreakable". This is NOT true. Both tempered and laminated glass are definitely breakable and many of the things that can break ordinary float glass can also break tempered glass. They are stronger than ordinary glass and do not break as easily. They only offer greater resistance in case of attempted break-in.