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November - December 2002

Weathering the Storm
Weatherstripping Products Have Faced Many Challenges 
and Have Emerged Stronger than Ever    
           by Howard McClure

With the challenges that have presented themselves to most industries since September 2001, the window and door industry has been able to show some growth, thanks in part to lower interest rates that have fueled refinancing and home sales. It seems each passing year brings new innovation and technology to our industry. Pick up any industry-related magazine and you will find both new and old products that are utilizing new materials and components. The weatherstripping aspect is no different in relation to windows and doors.

WINDOWSTRIPPING For many years weatherstripping was not given the highest consideration when designing a window and the variety of products available was limited. There were vinyl seals, polypropylene fin seals and pile seals (although these may be used today, it is not too often and mostly in low-end applications). Like many components, weatherstripping has been upgraded because of the high-performance polymers that are available to processors today. The availability of high-performance thermoplastic rubber (TPE), wrapped-foam urethane and thermoplastic rubbers have given design engineers new avenues to design excellent sealing systems. These materials have become more cost- competitive than other materials in recent years and processors have developed the ability to co-extrude on the less expensive weatherstripping base. Window manufacturers are now moving to custom, high-performance profiles rather than stock shapes. The driving force behind this is the need to develop new and better processes combined with improved materials for profitability and improved products. High-performance windows certainly will be enhanced by using better weatherstripping products.

The Future of Windows
With the continued development of high-tech materials and with innovations moving toward foaming these materials (density reduction via the creation of a cell structure), designers will continue to have solid avenues toward putting the highest value weatherstripping in their units. The days of cheap weatherstripping are over especially as the units themselves are upgraded to vinyl, fiberglass and composites. Building codes are more stringent than ever which is forcing manufacturers to apply even better weatherstripping into their systems. Maintenance-free windows will continue to dominate the market; therefore, there is no place for a weatherstripping that will not hold up under any condition. The foam core seals are here to stay, and rightfully so.

Residential Doors
What started with vinyl bulb seals and polypropylene fin seals, then progressed to TPE magnetic seals, have now evolved into high-performance wrapped foamed urethane seals referred to as foam weatherstripping. These products have high-performance characteristics at an affordable price point. The value is there and this is why more than 80 percent of today’s residential door market utilizes the product. At the retail level there has been a recent push to promote a magnetic product for the perceived “refrigerator seal.” However, one manufacturer has proven over the years that magnetic weatherstripping may seal your refrigerator, but it is not the appropriate choice for your door—not to mention the $1/door unit of savings by using straight compression foam weatherstripping. There are just too many factors that can cause leaks such as improper installation, out of square, wind loads, etc. Compression foam weatherstripping overcomes all these concerns.

The Future of Doors
Quite frankly, the future will belong to compression weatherstripping. Currently the number of shapes is somewhat limited due to the high capital costs of changing shapes. However, multiple designs are not required in the door industry like they are in the window industry. We may see a STORM coated or wrapped weatherstripping with a low-density closed cell foam core as the next advancement in this area. Also, due to more stringent building codes, the need to put immivesencents into the weatherstripping may become a requirement. Many manufacturers are focusing on the system (jamb, weatherstripping, sill and sweep), and there are many innovative systems which give consumers great choices. A door unit is not just a door unit anymore; long gone are the days when the only choice was steel or wood. Options have grown dramatically in an effort to meet the homeowners’ demand for style and energy efficiency. Manufacturers are paying attention to these demands, as opposed to in previous years when weatherstripping was just there, but not so important. Now it is a hot topic and everyone is paying attention to durability and 

Howard McClure is the vice president of the plastics group for the Loxcreen Co. Inc. in West Columbia, S.C. 

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