Sunday, December 16, 2012

Authentic True Divided Lites vs. Simulated Divided Lites


Woodstone® Authentic True Divided Lites vs. 
…Simulated Divided Lite ‘Superiority’ in Windows and Doors

Fact or Fiction?
Under the guise of recent technical service bulletins, some Insulating Glass (IG) manufacturers are reporting that SDL (Simulated Divided Lite) IG is “significantly more beneficial” than Authentic or TDL (True Divided Lite) IG. But careful review of the claim exposes flaws in the logic. Let’s consider each claim.

Reduced Material and Labor costs?
In a typical wooden SDL Window or Door, there is a wooden full lite frame, a full lite IG unit with a metal grille inside the IG air space, and then two additional wooden grilles – permanently glued to the sides of the IG and the SDL window or door frame.
An Authentic Woodstone® True Divided Lite (TDL) Window or Door has one wooden Divided Lite frame in which the TDL IG units are installed.
Labor savings realized by installing one large SDL IG unit rather than several smaller authentic lites are offset by the additional labor and material required to fabricate and glue the two additional wooden grilles to the glass and window or door frame. 

Reduced air and water infiltration?
Read the performance standards of any window or door before you purchase it. Woodstone® fabricates TDL windows and doors that meet or exceed the most stringent industry standards. 

Improved Thermal Performance?  
Woodstone® TDL windows and doors can include the same high performance glazing used in SDL windows and doors.

Large IG units have less seal edge stress than small IG units?
This is true. And it’s why the Insulating Glass Certification Council (IGCC) standard requires IG fabricators to annually test only small IG units. And Woodstone’s® TDL Insulated Glass has the highest IGCC CBA rating available.

Small IG units installed in high altitude locations require breather tubes to offset air pressure?
True again. But large IG units fabricated at sea level and installed at high altitude better have breather tubes too. Otherwise the air pressure differential will bow the glass and stress the seal.

Condensation is reduced with SDL units?
 Stainless Steel Spacer is about 4 times less conductive than the Aluminum Spacer with which some SDL units are fabricated.
However, the Composite IG spacer Woodstone® uses in its TDL IG units is 85 times less conductive than the Stainless Steel spacer inside the so-called Superior SDL air space.

SDL IG requires only one Federal identifying logo where Safety Glass is required?
According to the 780 CMR 2405.0 SAFETY GLAZING building code, when logos are specified, only one logo per sash or door is typically required with TDL too. In fact, in some cases, ‘the code’ allows for a Certificate of Compliance in lieu of any logos.
Always check your local building codes.

Reduced Breakage Potential?
At Woodstone®, we were somewhat surprised by this claim. Not because it’s false (and it is, patently false), but because it’s the breakage potential of the SDL that creates the greatest liability for the window manufacturer and the consumer.  
Woodstone® specializes in fabricating accurate landmark historic replicate windows and doors. Consider what happens if the IG breaks or the IG seal finally does fail. If your window or door is anything like the Woodstone® Palladian pictured above, and wind-blown debris or a stone thrown from a lawn mower breaks the IG, or you accidently scratch, crack or break the glass while cleaning it or doing routine maintenance… then what?
Glass can be damaged or break from time to time. Broken IG in a so-called Superior Divided Lite (SDL) unit requires expensive replacement costs. With an Authentic or True Divided Lite (TDL) Woodstone® window or door, just replace the small pane of IG.
Furthermore, most SDL units are significantly heavier than TDL windows and doors because the glass must be thicker and SDL IG is typically incompatible with historic restoration glass.
Even shipping and handling SDL units poses a higher breakage risk compared to Authentic True Divided Lite windows and doors.

The Final Analysis.
Using SDL IG in a vinyl replacement window is one thing. But as a long term investment, using SDL in a high quality historic landmark window or door, designed to last for generations, fabricated with restoration glass, fine lumber and hardware, and unique custom moldings and finishes inside and out, is another matter entirely. After all, high quality Woodstone® TDL windows and doors will last significantly longer than the duration of any limited IG warranty.   

Consider this: When a window or door is expected to last for generations, as have many of the windows and doors Woodstone® replicates, how many times will the so-called Superior SDL window or door have to be replaced - in its entirety – and at what future cost?

Most SDL IG manufacturers making the claim of superiority only warrant the replacement of the IG, not the window or door in which the IG is installed. And they typically honor the IG warranty only to the manufacturer purchasing the IG unit, not to the end consumer.
This explains why many SDL window and door manufacturers warrant their products to the consumer for shorter periods of time, even when the SDL IG is warranted to the manufacturer for longer time periods.  
Always read the warranty.



Authentic True Divided Lites (TDL) …

    …vs. Simulated or ‘Superior’ Divided Lites (SDL)? 



                                                            You decide.


3 comments:

  1. Thanks for your interest, Mr. Greenovich. The Palladian window you viewed is constructed entirely of American Black Cherry. It has no stain and is finished with a Marine Grade Tung Oil varnish inside and out.

    There are a couple of points to consider when deciding on the wood species and finish to use for your window project. For example, there are many varieties of Oak…primarily falling in the Red Oak and White Oak categories.

    Red Oak has a low resistance to decay, White Oak has a high resistance to decay. Hence, Woodstone recommends White Oak for exterior windows and doors.

    In any case, Woodstone recommends that all exterior surfaces be painted instead of using a varnish. Even the highest quality marine varnishes require periodic refinishing to keep the pristine look so familiar on wooden boats. Opaque paint, on the other hand, requires significantly less maintenance and Woodstone has excellent success in matching the wood grain appearance of most wood species with faux paint. Exterior varnishes are available. But be prepared to refinish the highly exposed areas of your windows and doors every 4 to 5 years or so, unless you want a 'weathered' appearance.

    The interior surfaces of you windows and doors are not subject to the rain and sun that deteriorate clear finishes over time and, therefore, using stain and varnish on the interior is not a problem. Color and stain matching to your floor, for example, is easily doable when you supply a sample to match.

    While asymmetric finishes are more expensive than single color applications, many Woodstone projects are completed with paint on the exterior and varnish finish on the interior. And there are many 'green' finishes available in paint and varnish that can be applied to LEED projects.

    Lastly, please keep in mind that Woodstone specializes in historic replications and, therefore, is purely custom. You can specify just about anything you want.

    Again, thank you for your interest.

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  2. P.S. Yes, the windows in the Palladian open. In fact, that Palladian has a weight and pulley double hung window on the left, an out-swing casement window on the right, and an arched top in-swing casement pair in the center. All of the glass is True Divided Lite insulating glass.

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  3. Mr. Damien: Thank you for your comments.

    But please keep in mind that vinyl is not more durable than wood when compared to the wood species typically used to fabricate Woodstone Windows. Woodstone uses Genuine Mahogany, American Cherry, White Oak and other wood species rated with very high resistance to decay. We expect our windows to last for a lifetime or more, as did many of the windows we replace in historic districts.

    Are Woodstone's wooden windows affordable compared to vinyl? That depends on how much time and energy you want to spend replacing a vinyl window over the useful life of a Woodstone window.

    Keep in mind that when vinyl window manufactures claim their windows are maintenance free, they are correct from one perspective - vinyl windows can't be maintained. When they break or fail, they must be replaced, recycled (if possible) or dumped in a landfill. Even the finish provided with most Woodstone windows is warranted to last longer than an entire typical vinyl replacement window.

    We're not saying landmark wooden replicate windows are right for every job.

    But if you're replacing historic windows that have functioned well for 100 years or more, and the building in which they are being replaced is a historic landmark, investing 3 times the price of an inexpensive vinyl replacement window for a high performance wooden landmark replicate window is worth it when you consider that the vinyl window will have to be replaced several times over the otherwise useful life of the Woodstone wooden window.

    This is but one more reason to consider properly fabricated historic landmark wooden windows. There are several other very good reasons discussed in this blog and we encourage our readers to comment on them.

    Again, thank you for considering Woodstone and we look forward to hearing from you again soon.

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