The Myths about Vinyl Windows

Vinyl windows of all kinds have made their way into the market-place over the past 20 years or so, touted as being energy efficient, durable, and a cheaper option to wood windows.

Mismatched vinyl window in wood opening
Vinyl window in wood opening.

I’m here to confess that I installed a few vinyl windows when they first hit the Chicago market in the mid to late 1990’s; that is, until I started questioning the claims being put forth by the different manufacturers regarding the ‘benefits’ of vinyl windows. Once I stepped back and looked at the claims objectively, here’s what I found:

CLAIM: Vinyl windows are energy efficient.

FACT: Some vinyl windows are in fact energy efficient in theory. However, most are constructed using hollow extrusions which offer little in the way of R-Value (resistance to heat transfer). The glazing itself may or may not be very efficient depending on the type of glass specified. The weather stripping, a key element to window performance, is hit or miss in my opinion; some manufacturers get it right, but many don’t pay enough attention to this simple detail & as a result the performance of these units suffer.

The operating hardware is another often overlooked area. Too often, low quality hardware is used and because of its poor performance, the window doesn’t seal well when closed and locked – which, by the way, is necessary for optimum resistance to the weather. This hardware is often acquired from low budget suppliers that import or fabricate the hardware to the lowest possible specification. Rarely is a name brand supplier used, resulting in difficulty in obtaining matching parts in the future. In contrast, most manufacturers of wood windows purchase the hardware for their units from one of a couple well established companies, ensuring the availability of replacement parts for years to come.

CLAIM: Vinyl windows are durable – perhaps more durable than wood windows.

FACT: Vinyl itself is generally durable when exposed to moisture. However, a problem with vinyl is that window components fabricated from it are often difficult to fasten at their joints, relying on heat welding or specialized hardware rather than the interlocking joinery found on wood windows. If the components aren’t fastened properly, the end result is a unit that can (and often does) pull apart at the seams over time.

Another issue is that vinyl is very susceptible to thermal expansion and contraction. Here in the Chicago area, temperatures can range from -25f in the winter to +105f or more in the summer. Vinyl doesn’t generally react well to temperature extremes, becoming brittle in cold weather and pliable in hot weather. This expansion and contraction can also lead to the joint failures mentioned above and the larger the unit, the more movement & the greater the chance the window will self-destruct. By contrast, wood is practically unaffected by even extreme temperature swings.

Durability in vinyl’s case is a double-edged sword: We of course want durable products on the exteriors of our buildings & while it’s true that vinyl won’t rot, this trait also means it’s not biodegradable & therefore can be a challenge to dispose of properly. It shouldn’t be placed in the regular waste stream as it clogs landfills and can’t be incinerated without producing toxic pollution, so what becomes of it? Recycling is an option, but unfortunately some studies indicate the percentage of vinyl that’s actually recycled in this country to be in the low single digits. The reason for this appears to be twofold: First, there simply aren’t very many facilities that are equipped to process used vinyl. Second, vinyl itself is relatively inexpensive to produce, so there seems to be little financial incentive for recycling a cheap material. So what to do with it when the component it’s incorporated into fails? (And everything has a finite lifespan).

Wood of course has none of these challenges; yes it needs to be protected and maintained, but the fact is every component of a house exposed to the weather – particularly operational elements – need regular inspection and maintenance. If a wood window is damaged, chances are it can be repaired. If one or more elements are damaged beyond repair, they can probably be replaced. The pieces being replaced can either be chipped up or simply allowed to biodegrade. In reality, a good quality wood window that’s properly maintained should last a lifetime or more.

CLAIM: Vinyl windows are maintenance free.

FACT: This is a complete myth. Nothing is maintenance free. All the operational & exterior elements of a building require periodic inspection, repair, and eventually, replacement. While it’s true one doesn’t have to paint vinyl windows after installation, eventually the vinyl may fade (another inherent flaw to the product) or the owner may simply want to change the color – not necessarily an easy feat, given the fact vinyl can be very difficult to get paint to adhere to successfully.

Perhaps the biggest fallacy in this myth is the generalization that all vinyl windows are maintenance free, as it assumes all vinyl windows are created equal. This is simply not true. As with most products, there are varying levels of quality. The “premium” windows may be fairly durable, but even they may be susceptible to some or all of the problems mentioned in this piece.

Unfortunately, it seems that most vinyl windows sold and installed today are not “premium” quality, but rather lower end products. These units often come from fairly small local fabricators who may or may not still be in business if and when the window fails or parts are required for repair (as is also the case with their hardware).

To put this in perspective, consider the fact there are roughly a dozen or so major manufacturers that produce wood windows in the U.S. Most of these companies are well established, with many having been in business for several generations or more. In comparison, there appear to be literally hundreds if not thousands of vinyl window companies scattered throughout the country. They tend to come and go at an alarming rate, leaving behind many poor quality windows that often can’t be effectively repaired.

Speaking of repairing windows, vinyl windows are often a challenge to repair for a variety of reasons. They generally consist of hollow extrusions for the sash, or the frame into which the glass is placed. Unlike wood windows where the glass is placed on top of the frame & can be readily removed for replacement by a skilled craftsman if need be, these vinyl extrusions often encapsulate the glass. They’re fastened at the corners, often through the use of heat welding which fuses the vinyl together, making removal of damaged glazing & installation of new almost impossible in many cases.

And the glazing will almost certainly have to be replaced at some point, because insulated glass has a finite lifespan. This glazing is made up of multiple layers of glass separated by an air space between each pane. These air spaces are sometimes filled with inert gases & are what provide the actual insulation in the assembly. It’s imperative that these spaces be completely sealed off from the surrounding environment, as outside air that makes its way between the panes can carry pollutants & moisture, reducing the efficiency of the insulated glass.

Manufacturers of vinyl windows typically use butyl or silicone to seal the edges of the glass, as well as the glazing to the vinyl frame. The problem with this is that glass & vinyl are dissimilar in their thermal performance. As mentioned previously, vinyl tends to move a great deal in relation to wide temperature fluctuations. On the other hand, glass doesn’t move nearly as much. This difference puts stress on the frame & on the sealant used around the glass. After a while, the sealant will fail, permitting outside air to enter the insulating panel. The result is glass that has a cloudy or dirty appearance, as well as greatly reduced efficiency. The only way to repair the problem is to replace the glazing, but we’ve already discussed that, haven’t we?

As if all the above outlined shortcomings of vinyl windows aren’t enough, there’s more, with perhaps their biggest drawback being that they’re, well, vinyl.

PVC (Polyvinyl Chloride) manufacturing is a nasty process that has been proven to do great harm to the environment. One need not be a “tree-hugger” to understand the implications from such a process.

To top it off, vinyl windows are generally not nearly as attractive as their wood counterparts. Since vinyl itself is fairly weak in small cross sections, manufacturers have taken to fabricating disproportionately large components to make up for its inherent weakness. This means that the clean, crisp, delicate lines often found in wood windows simply can’t be recreated in vinyl. And if you’re looking for the warmth of natural wood, forget it. Have you ever heard anyone exclaim about the “natural beauty of vinyl”?

So what alternatives are there to vinyl? The answer often depends on the application. In general, a good quality wood or clad wood window that’s properly installed and maintained will outperform and outlast most vinyl units.

That said, we don’t recommend installing wood windows in high-moisture areas such as showers and next to ground level. Come to think of it, we don’t encourage bad building practices, period. So we would encourage you not to install a window in the above situations. However, we also recognize reality often gets in the way of ideal practices, so we’d recommend using a fiberglass unit rather than a vinyl one when moisture or the desire for low maintenance is a primary concern.