Window Maintenance

Troubleshooting Vinyl Windows

Technical Questions

Glass Related Questions

How do I clean window frames?

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. Over time, the exterior surface of window frames and doors may collect a layer of dirt, depending on environmental conditions. Rainfall will usually be sufficient to remove accumulated dirt. However, in places 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 used in paint are almost identical to those used in vinyl, but vinyl's colour goes all the way through. A little rubdown with Soft Scrub will bring vinyl back to its original brilliance.


How do I clean glass?

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 matter 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 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 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?

Parts exposed when the window is open should be simply wiped clean, to remove 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 dirt-free 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?

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 faceplates. With sliders or single hung windows, a silicone spray (candle wax / furniture polish) can be used to lubricate the sashes to help them to slide more smoothly. With 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 them with a soft brush. We would like to stress that at all times care should be taken not to overreach or risk falling.


What are Self-cleaning windows?

Pilkington Activ™ is manufactured with the same advanced pyrolytic technology used to produce glass panels for electronic and photovoltaic solar cell applications. Applied to clear float glass via on-line chemical vapor deposition, it is an integral part of one surface of the glass, and lasts the entire life of the glass. As windows stay cleaner longer.


Why do my windows leak? Is this normal?

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 to allow 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?

Excess humidity manifesting itself in the form of a thin film of water on a cold surface is called condensation. You can see this on a humid, hot summer day when condensation appears on a cold glass. If the temperature changes but no water vapour 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 call-backs.


What is “window sweating”?

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.


Is condensation bad?

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 wetting adjacent walls and floor surfaces, but in more severe cases can cause wood rotting and the paint and plaster deterioration. The problem takes on a special significance to the builder because the homeowner frequently assumes that window construction or installation is faulty. The homeowner 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.


What causes condensation on windows?

There are several factors that put moisture into the air and cause condensation on windows. Normal breathing and perspiration add three 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, 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. - Open toilet lids that allow more evaporation. - Exhaust fans that aren't used during baths and showers to remove the moisture. - Excessive use of things like steamers, plant misters or teapots. - 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. - Doors that are too tight to 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, washrags or towels repeatedly left lying 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. - Floors left very wet after mopping.


Do windows cause condensation?

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 airflow in your home and making it more airtight. Tighter homes actually retain more humidity.


Where on a window does condensation normally form? Why?

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 vapour 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?

Yes. 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, occupants can control window condensation, once they understand the causes.


How can I reduce condensation?

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 that measure humidity are called hygrometers. They can be purchased at most reliable hardware and home centre stores. As a guide, the following chart will help:

Outside Temperature °F Inside Relative 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?

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?

Argon is an odourless, colourless, 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 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 spacers?

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 call-backs. Non-conductive warm edge spacers reduce heat 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 percent and boost the edge temperature by around 5°F, thereby reducing condensation.


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

The main advantages are:

  • Reduced energy loss (heat and cold)
  • Reduced harmful ultraviolet (UV) rays
  • Improved environmental friendliness


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

Low-e glass improves the insulating value of a window roughly as much as adding an additional pane of glass. Low-e glass combined with argon gas boosts energy efficiency by nearly 100 percent 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 percent 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 percent of the window's overall cost. It's an easy decision.


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

Windows are thermal holes. An average home loses approximately 30 percent 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: for example, 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:


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.


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?

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 percent of the harmful UV rays.


What is low-e glass?

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 percent. Read more about low-e-glass.


What is tempered glass?

Tempered glass has a surface compression of not less than 10,000 psi (pounds per square inch) 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 shatters into small pebble-like harmless pieces without sharp edges. This is by design and is proof of a well-tempered product, not 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?

Laminated glass is a combination of two or more glass sheets with one or more interlayers 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 percent of the sun's harmful UV rays.


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

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. However, they are stronger than ordinary glass and do not break as easily. They do offer greater resistance in case of attempted break-in.