A Wingnut Question: Why Don’t Car Doors Leak While Windows Do? – GreenBuildingAdvisor

Building Matters

Inexpensive cars drive at 70 MPH in the rain without leaking while our homes—particularly the windows—leak with the house sitting still. What about using gaskets to install windows?

I have had three recent high-performance projects completed by leading architects and/or builders with excellent crews, and the windows have leaked—or, rather, the window installations have leaked. Why? I think because the installations

• were complicated;
• were custom; and
• involved details not within the very general installation guidance/requirements from the window manufacturers.

That got me looking at car doors and their gasket systems. Car-door gaskets are very similar from one auto manufacturer to the next, and any door shape/configuration is way more complex geometrically than any window. How do they do that?

A conversation with an auto manufacturer enclosure engineer

Some years ago, I did some nondisclosure work with a major auto manufacturer interested in building modular homes. I called my contact there and he kindly connected me to the lead engineer in their enclosure department—one of the geeks responsible for doors, windows, windshields, hatchbacks, and roof windows. I got one hour of his time and these key takeaways:

• Large flanges/chambers: The gaskets are recessed into chambers with big metal flanges, making them quite “pressure-protected.”

• One bulb or two for buildings? Auto gaskets are made up of two bulb gaskets (one on the door and one on the frame) because they see a lot of movement (opening and closing as well as flex). For windows in buildings, maybe a single bulb could work.