Windows are an important component of a home. In addition to enhancing the esthetic beauty of the house, windows can provide fresh air and ventilation to the home, allow daylighting to brighten interior spaces and keep out harsh outdoor elements (wind, rain, snow).

Buying new windows can be a daunting task, especially for the uninitiated. Knowing the type of window best suited for your home and geographic location can help you choose a window that reduces direct drafts from air leakage and the potential for damage from water leaks. It’s important to understand how windows perform with respect to these factors. Equally important, knowing what to look for in a window can help you avoid buying something you don’t need.

The ABC’s of Window Performance

The performance of windows sold in Canada is defined in a Canadian Standards Association standard called CSA A440 (Windows). This standard sets the type of materials that are to be used in the manufacture of windows and some minimum material properties, such as thickness, hardness and durability. The A440 Standard also defines minimum performance levels for windows evaluated under a standardized set of conditions. The characteristics defined in the A440 Standard include:

• Airtightness*
• Watertightness*
• Wind load resistance*
• Ease of operation
• Resistance to forced entry
• Condensation resistance
• Screen strength

All windows sold in Canada must be evaluated for their performance level in airtightness, watertightness and wind load resistance — the characteristics marked with an asterisk (*) in the list above. This About Your House focuses primarily on these characteristics. Evaluating windows for the other characteristics is voluntary, so not all windows are evaluated for their ability to resist, for example, forced entry.

A — Air Leakage

Why is an Air Leakage Standard so Important?

The uncontrolled movement of air into or out of the house is a cost to the homeowner. For example, any cold outdoor air that leaks into the home (air infiltration) must be heated to room temperature to maintain the comfort of the occupants, so air infiltration is a heating cost. The same problem occurs in air-conditioned homes during the summer, when warm outdoor air infiltrates, resulting in an additional cooling load.

When interior-conditioned air (either heated for winter or cooled for summer) leaks to the outside, the homeowner also pays the energy costs associated with the air leakage.

Windows are tested for air leakage by applying a standardized air pressure (roughly equivalent to a 40 km/h — 25 mph — wind) across a window of a standard size. The amount of air that leaks through the window at that pressure difference is measured.

Depending on the test result, windows are given one of the following airtightness performance ratings:

• A1 (somewhat leaky),
• A2 (slightly leaky), or
• A3 (not very leaky).

In general, fixed windows tend to have higher airtightness performance ratings because they allow less air to pass through the unit than windows that open and shut. Slider windows tend to be leakier than casement windows. All windows sold in Canada must at least meet the A1 performance level to comply with local building codes.

A higher A rating is a desirable attribute for a window if your home is located in a region known to have frequent high winds or gusty winds.

The rated performance only indicates the window’s leakiness relative to other products evaluated. Installation procedures, manufacturing tolerances and other factors also contribute to performance of an installed window. Window units are not evaluated when installed in a wall, so a window rated at a specific performance level may not perform at that level when installed.

Window rating programs are intended to allow consumers to compare similar products, not to predict, for example, air leakage rates. The thinking is that, if one window has a better airtightness rating than another, it will have less air leakage when installed.

B — Resistance to Wind-driven Rain

Windows may also allow water to leak into the house during rainstorms, leading to water damage of interior finishes and potential mold growth. Because of this, all windows sold in Canada are evaluated for their ability to resist water leakage and for resistance to wind-driven rain. Water is continuously sprayed onto the outside of a standard-sized window under standard temperature and air pressure conditions.

The window is rated in accordance with the highest air-pressure level for which no water leakage occurs.

A B1 rating is assigned to a window that exhibits no water leakage at a relatively low air-pressure difference across the window. It is the lowest permissible result.

All windows sold in Canada must meet at least the B1 rating to comply with local building codes.

Every rating number above B1 represents the highest air-pressure condition for which no water leakage occurs. For example, a window rated B4 that shows no water leakage at a test pressure of 400 pascals (Pa) — the metric unit of pressure — presumably leaks at higher pressures.

The highest possible rating in the A440 Standard for resistance to wind-driven rain is B7, equivalent to a window resisting water leakage at wind speeds greater than 120 km/h (75 mph.) — a high-performance product.

As noted for air leakage, the B rating does not necessarily indicate the performance of the product as installed. It should only be used to compare products. The B rating is a very important performance index in coastal climates, where wind-driven rain is relatively common. A window rated B2 would be the minimum advisable for low-rise houses (typically four stories or less) in most of Canada, except for the areas mentioned in Table 1.

Table 1 — Suggested Minimum Ratings for Wind-driven Rain Resistance

The above B ratings are appropriate for low-rise residences in relatively sheltered areas, and are only a suggested minimum. Building height, shape and location, such as on hilltops, promontories or bluffs, can increase the effect of wind-driven rain, so that higher B ratings are advised. In new construction or replacement of existing windows, it is advisable to discuss and choose the window rating levels with a design professional.

C — Wind Resistance

Windows are also tested for their ability to resist wind pressures without deforming too much and without blowing out of their frames. Test windows are subjected to a large air-pressure difference to simulate hurricane-force winds (120 km/h and higher). The resulting deformation of the framing components is measured, with the window receiving a rating ranging from C1 — deflection or blowout of the window at gale-force winds (62 – 74 km/h — 39 – 46 mph.) — to C5 — resistance to extremely high wind pressures without blowout or permanent deformation. Windows rated C5 are appropriate for some high-rise buildings, or for low-rise buildings in very windy climates.

A window rated C2 is the minimum advisable for low-rise houses in most of Canada, except for the areas in the Table 2.

Table 2 — Suggested Minimum Ratings for Wind Resistance

The above C ratings are suggested for low-rise houses in relatively sheltered areas. They are typical values for the regions listed. Building height, shape and location, such as on hilltops, promontories or bluffs, increase the effect of wind pressures, so higher C ratings are advised. Higher ratings are also suggested if local wind conditions are higher than the average values for the regions listed. Typical wind-pressure levels for the regions listed (upon which the suggested C ratings are based) are taken from meteorological data valid for the location of the meteorological station. There may be, for example, regions in the Gaspé or in southern Alberta for which C5 ratings would be advisable.

Voluntary Tests

Manufacturers may, but are not required to, have their windows tested for ease of operation, resistance to forced entry, condensation and screen strength.

Ease of Operation

Many operable windows are tested to ensure that their operation is relatively smooth, with no jamming of operator mechanisms. The amount of force required to turn operator cranks or slide windows open and closed is measured in the test and cannot exceed set levels.

As is always the case with standardized testing, however, the performance of the product sold may vary slightly from the rated value. The CSA Standard only indicates whether a window model meets or does not meet the requirements of this (voluntary) portion of the test. Consumers are encouraged to test window operation for themselves, noting that showroom models may have been opened and closed many times, and that dealers are unlikely to display products that do not operate properly.

Over time, gaskets and seals will tend to wear, so that window operation will become easier, but the window will also tend to leak more air and water.

Resistance to Forced Entry

The CSA Window Standard includes a test method to determine a window’s resistance to forced entry, but consumers are advised not to rely entirely on this rating for security of their person and property. A consumer-rating index is no substitute for normal precautions against unwanted or unlawful entry.

Condensation Resistance

The CSA procedure contains standardized test methods to evaluate a window’s tendency to allow condensation to form on the glazing or framing members under winter conditions. Condensation, due to air leakage or heat loss through the unit itself, can damage adjacent building materials or cause fungal growth.

The warning that rated performance is different from actual performance of products sold is never more important than with this index. A wide range of variables can influence the formation of condensation, including:

• air leakage, through the window and around its perimeter;
• relative humidity of the interior air (the higher the humidity the greater the potential for condensation);
• where the window is installed in the wall (windows installed farther to the outside of the wall tend to exhibit more condensation);
• the presence (or absence) of convection heaters below the window;
• placing objects (plants, photographs, books, and so on) on the windowsill tends to restrict air movement on the window and thus promotes condensation.

Condensation resistance of windows has an index called the Temperature Factor (TF). The TF can be thought of as an indication of whether the interior surface temperatures are more like the interior or the exterior. If the interior surface temperatures of the window were the same as the outdoor temperature, the TF would be 0; if the interior surfaces of the window were as warm as the room air, the TF would be 100.

If a window is tested for condensation resistance, the minimum level required to meet the A440 performance standard is TF 40. This is approximately equivalent to a double-glazed window with a thermally broken metal frame. Higher ratings are suggested for humid climates, for example, near lakeshores, oceans or in river valleys.

Higher ratings may also be necessary in homes where interior relative humidity levels are higher than average — for example, where frequent showers are taken, or an unusually large number of plants are maintained, or food preparation involves large quantities of boiling water. However, in situations where high indoor humidity levels are expected, it may be more appropriate to address that issue directly (for example, by installing a dehumidifier or exhaust fan) rather than buying condensation-resistant windows.

Screen Strength

Operable windows usually feature a screen over the open portion of the window to keep insects outside. Depending on the force that can be applied without separating the screen from the frame, the screen is rated as either “Standard” or “Heavy Duty.” It is important to note that the screen strength test is only designed to determine the ability of the screen to resist nominal loads. An insect screen is neither a fall-prevention device nor an anti-theft feature: it is only intended to keep insects out.

Conclusion

Windows must be carefully selected to meet your needs. They must be suitable for resisting certain environmental exposures (such as rain and wind) and be within your budget. It takes care for the average homeowner and many professionals to make the best selection.

All windows sold in Canada must be evaluated for three key performance criteria, commonly referred to as the A-B-C window ratings.

• A — airtightness (levels A1 to A3)
• B — water resistance (levels B1 to B7)
• C — wind resistance (levels C1 to C5)

Generally speaking, the higher the numbers, the better the window performance. Choose a rating level that satisfies the environmental conditions of your home. Determine if any of the voluntary performance criteria are required for your window(s) and if they meet the required standards.

Westeck is not responsible for customer’s own glass at any time during insulation, fabrication, tempering, loading/unloading, transportation or storage. All claims for damaged or defective goods must be made within 48 hours of receipt. Westeck assumes no responsibility for breakage of any kind, after the customer receives the order. Freight damage by common carrier must be claimed against the freight company. Westeck assumes no responsibly for third party freight damage.

For safety identification, Westeck uses a logo on all heat treated glass. If your application does not require a logo, you must indicate on each order that you place with us. Westeck assumes no responsibility for code compliance on glass that has been ordered without logo’s.

Westeck views pinhead as having no specific pattern orientation and cuts accordingly.

When ordering shapes, always list: BASE x LEFT x RIGHT x TOP. Westeck assumes without exception, that glass is measured and ordered from the outside looking into the building. Cutting tolerances are: +/- 1/16″…3-6MM, +/- 1/8″…8-12MM, +/- 3/16″…15-19MM

Cleaning the Window

When cleaning Westeck Windows use the mildest cleaners’ possible. NEVER use solvents, abrasives, or acid based cleansers on or near the product. Some chemicals can harm vinyl and other window components. NEVER use hydrochloric or muriatic acid based cleaners – i.e. ‘brickwash’ on or around the product. These acids can be very harmful to hardware, reinforcing, and glass. Doing this will void the warranty.

You can clean the glass with any common household glass cleaner or mild detergent. DO NOT use any petroleum-based cleansers or solvent. We recommend using soft lint free cloths; paper towel is fine too. Be aware that soil deposits may contain abrasive elements and vigorous wiping, scrubbing may cause scratching or damage to the glass surface. After the soil is removed, all soap or cleaning solution and dirt debris must be thoroughly rinsed off the glass. Rinse and dry all cleaning solution from widow gaskets, sealants, and frames. On the area where the lable was removed from the glass, water may ‘bead up’ for a time.

You should not add any attachments to the window or glass without the manufacturer approval. Doing this may void the warranty.

Be aware that exposure to hard water or sea air may result in mineral deposits on your Westeck Glass. Prolonged exposure may damage glass surface. If it does not rinse away, ensure this is cleaned by hand as soon as it is noticed. Hard water mineral deposits from any source, including overspray from lawn and garden sprinkler systems may build up over time and that can permanently damage the glass; therefore, we recommend you do not expose your glass to repeated contact with any hard water sources. If your Westeck Glass is subjected to hard water exposure, it should be promptly dried/cleaned with a cloth to avoid spotting, streaking or damage.

As with any glass:

• DO NOT use scrapers or razor blades to remove stubborn deposits or lables
• DO NOT use abrasive cleaning solutions such as Ajax® or Comet®
• DO NOT allow splashed materials such as paint, stucco, mortar, or drywall putty/gyproc dust to dry or remain on the window frame, window seals, or glass surface.

 
Cleaning the Window Frames:
Keeping your windows and doors clean is more than just the glass. Here are some helpful tips for cleaning vinyl frames and sashes of your Westeck Windows and Doors effectively without damaging them.

• Clean window and door frames with a mixture of mild dish detergent and water.
• Abrasive cleaners or solvents are never recommended because they might cause permanent damage to frame finishes. Mild non-abrasive soaps are usually safest for most dirt and stain removal.
• Always rinse completely with clear water and wipe dry.
• Ensure drainage holes are always clear of dirt and debris that might obstruct free flow of water, both inside and outside of the window or door in the bottom of the frame and sash.

 
Initial Installation

During and after construction, the product should be protected from spills, runoff, and over-spray from common building materials: Installation sealants, paints, and drywall/gyproc putty or dust should be removed promptly.

Periodic Maintenance

Every 6 months to one year thoroughly clean hardware and hardware points of contact in casements and awnings as well as tracks in slider and patio door profiles. Spray a silicone lubricant on hardware points of contact (casements) and inside tracks, bottom and top of slider and patio door profiles. Check all drainholes, inside and out, and ensure they are clean and free of obstruction(s). Check all weatherstrips and bulbseals for tears, or looseness and replace/reinsert if found.

Periodic condensation on windows is normal, particularly in cold weather. However, hidden condensation can become a significant problem if not corrected. This Guide to Energy Management will help you recognize the sources of excessive condensation and take action to remedy the problem.

What is condensation?

Air in the home is actually a mixture of air and invisible water vapor. 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 vapor into a liquid and usually happens when the vapor cools. The temperature at which the vapor 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.

As a rule, the coolest visible surfaces in a home will be the cold water pipes, windows, and hinges and locks on exterior doors. It is on these surfaces that condensation first becomes apparent. However, condensation may also occur in areas where it is not visible such as in the attic and exterior walls.

Condensation on windows may be little more than a nuisance, but condensation on walls and ceilings can cause paint to peel. Hidden condensation can lead to problems that range from mould, mildew, and stains on walls and ceilings, to dry rot and destruction of a wood frame structure.

Condensation on windows

Windows are one of the coldest surfaces in a house. Condensation forms on a window when the temperature of the glass is below the dew point of the air and the warm air that contacts it cools rapidly. Like glass, metal is also a poor insulator. If the window has a metal frame, condensation also occurs on the frame.

Hidden condensation

Hidden condensation can occur when warm moist air migrates into the walls, attic, or other interior areas of the structure. Most of the moisture is carried into walls and attics by air leaking through openings for plumbing, piping, electrical boxes and wires, gaps between framing and drywall, attic hatches and other openings.

If at some area in the wall or attic, the moist air encounters a temperature below the dew point, condensation will occur. Moisture inside the walls may also cause blistering of paint on exterior siding. New housing is required to have a continuous vapor barrier, sealed at all penetrations. This requirement is intended to prevent, or at least severely inhibit, hidden condensation

If the temperature is low enough, moisture may deposit as ice or frost. If the amount of moisture is small, it may change back into water vapor with a rise in temperature and be carried away by natural air movement. However, large deposits of ice will melt and soak insulation materials, ruin interior and exterior finishes and possibly lead to structural deterioration.

Causes and solutions

Activities such as cooking, washing or bathing will often result in some condensation on windows for short periods of time during cold weather. Other than causing deterioration of the finish on wood frames, sills or casings, such condensation is harmless. Therefore, moderate, intermittent condensation on windows is probably no cause for alarm. However, if windows are consistently wet, or water stains appear on ceilings or walls, prompt action should be taken to avoid further problems.

The quickest and most effective response to a condensation problem is to increase the ventilation of the house. This can be done in several ways:

• Using exhaust fans, particularly when cooking, bathing or washing
• Opening the fireplace damper
• Opening doors and windows to increase the amount of outdoor air being brought into the house

Outdoor air, when heated to indoor temperatures, will be dryer than the air indoors. Increased ventilation will reduce condensation, but it doesn’t correct the cause. The cause should be located and corrected.

NOTE: Installing a dehumidifier does not solve overall home humidity problems, it is only capable of lowering the relative humidity to 50 or 60%.

Conventional wisdom has it that PVC is not paintable. Is that a reasonable statement? Had Westeck not already been painting uPVC for eight years we’d say the same thing. So: Can PVC be painted?

The fact is that uPVC and cPVC (PVC from here on) are difficult to paint. The reason is, is that PVC has a low surface energy. All materials and liquids have a “surface energy”. The scientific unit of surface energy is Dynes/Centimeter. For purposes of discussion we will talk about the surface energy, SE, of water and how it relates to PVC.

Water has a surface energy of 72DYNE (DYNE is short for Dynes/Centimeter) and PVC has a surface energy of 41DYNE (list of the surface energy of various polymers). Since water has a higher surface energy (SE) than PVC, it will bead up and roll of like: “water-on-aducks- back”. In order for the water to “stick” or “wet out” onto PVC, PVC has to be treated to rise the SE of the PVC above the SE of water. Can this be done? By the average consumer? …well…no…but don’t give up yet, and read on… The average consumer can do two things to increase the SE of PVC, the first of which is to sand the surface lightly. This will remove the surface waxes to the degree and create more area for the water to wet out. We recommend you use Green Scotch Brite because sand paper will load up very quickly with the surface waxes on the PVC, this raises the SE. The second way to raise the SE is to wipe the PVC with Acetone. Acetone is detrimental to PVC. If one were to immerse PVC in Acetone, it would break down the molecular structure over time and destroy the PVC. This, however, can be a benefit when preparing PVC for painting. The Acetone does two things: (1) it swells the surface making it slightly more porous and (2) it disperses the surface waxes that are inherent on the surface from the extrusion process when it is manufactured. So, Acetone will also raise the SE of the PVC.

There is another piece of the equation that has to be considered. Even if a consumer prepares the surface as described, the SE of PVC will never reach the SE of water (with these techniques) which is 72DYNE and with all the best preparation, the SE of the PVC will be variable due to the waxes that are external and internal to the PVC. To combat this, paints made of a blend of acrylic and polyurethane, (i.e. special latex paints) have been formulated with additives to reduce the SE of the liquid paint. These additives reduce the SE of PVC paints down to 34DYNE which is lower than the untreated SE of PVC.

In theory one would not have to treat the PVC if the paint has a surface energy below the PVC; but there’s a problem with theory – reality. Empirical results suggest a combination of good surface preparation and a paint coating with a low SE can result in good adhesion of paint to PVC.

There is a lot more to it than that: the paint formulation is actually a cacophony of chemistry. Every micro ingredient and every pigment change can change the adhesion of the liquid paint to the PVC substrate but that’s beyond the scope of this article. Suffice it to say that the paints developed for PVC niche have been tested for adhesion on PVC each and every time a change is made to the formulation.

Yet another layer of the Onion to remove

At Westeck we subject the PVC to a flame treat process that can raise the surface energy from 42DYNE to above that of Waters 72DYNE.

To try to better explain it. When the surface energy of PVC is raised to this type of energy be thought of as “micro anchors points’ to which the paint can adhere.

In our flame treat process, we subject the PVC to a very lean burn flame of natural gas. The temperature of the flame is roughly 5000°F. At these temperatures a low temperature plasma is created. In effect the excess oxygen in the flame is heated to the point of ionization. Which means that the oxygen loses an electron and becomes a positive ion. In this state the oxygen is very very reactive and wants to bond to another atom or molecule. In our process the 0+ is introduced next to the PVC and bonds to the PVC. The result is the surface energy of the PVC is raised tremendously. There is another benefit of the flame process which is to remove the surface waxes on the PVC raising the surface energy of the PVC.

So, whew… there you have it. PVC can be painted but it has to be prepared correctly and it needs to (note: I said needs to, not has to) be painted with paints that are formulated for PVC. At Westeck we also put reflective pigments in the paint so that the PVC will not rise above it’s distortion temperature of 140°F. (note: for dark colors PVC has to have reflective pigments)

With our reflective pigment paint you can paint your windows with black paint and not have distortion issues –

At Westeck Windows and Doors we have merged the markets between Clad-Wood windows and Vinyl windows. Take a look at the picture, this window looks exactly like a contemporary aluminum-clad or vinyl-clad wood window but now you can get better performance at a fraction of the cost.

Can PVC be painted: ABSOLUTELY and it’s guaranteed for 10 years!!

Original article by Abe Gaskin MGM Industries June 2011