Thin Thresholds, Delightful Doors


Did you know that the revolving door was invented in 1888 by Philadelphia native Theophilus van Kannel? The revolving door is now commonly used in skyscrapers because it reduces the amount of noise that enters the building and serves as an airlock to drive down heating costs, in addition to preventing collisions between passers-by. Just as the revolving door offers benefits to the skyscraper, so do home doors offer protection for the conscientious homeowner. I would like to review today some basic door types, purposes of a door, threshold types, and elements of the door system.

Doors come in many shapes and sizes, and are adapted to suit various purposes. Garage doors, storm doors, and sliding doors are just a few variations of doors.

The purpose of a door is two-fold: as a passageway permitting entry into a space or location, and as a deterrent to the inclemency of the weather. Delving deeper into the latter purpose, we know that a door reduces air transfer and eliminates pest entry points. With regards to the former, weatherstripping, thresholds, and sills are all crucial elements to keeping the entryway maintained and usable.

The threshold of a door is the raised bump (much like a miniature speed bump) that is located under the edge of the door. The threshold ensures a tight fit between the door and the floor, preventing any uninvited pests from entering, as well as stopping air flow. There are at least five types of thresholds: wood (oak), combination (wood and metal), aluminum (non-adjustable), aluminum (adjustable), and combination (sill/threshold).

The wood (oak) threshold is simply a piece of wood shaped in the form of a half-hexagon, but with interior angles greater than one hundred and twenty degrees.  

The combination (wood and metal) threshold consists of a metal ramp for the exterior side (the side facing the extremities), followed by a half-cylindrical rubber gasket, followed by a wooden mini-ramp which faces into the inside of the home.

The aluminum (non-adjustable) threshold and aluminum (adjustable) thresholds both perform essentially the same function, and the author of this article is baffled as to the difference between non-adjustable and adjustable.

The combination (sill/threshold) consists of a low-gradient mini-ramp made of metal placed above a piece of wood which acts as the sill.

The door sill is the piece of wood directly underneath the entryway which acts as a platform for the entryway or doorway.

The elements of a door, thus far covered, are the door sill, the door threshold, and the door itself.

The last aspect of the door system worth mentioning is the brick molding, which is: the trim surrounding the door, often profiled, miter-cut, which fits between the door frame and the siding.

To summarize, a few elements of doors have been detailed, along with threshold types, the purposes of a door, and door types.


Yours truly,


Ryan Hartwig

MultiConsult LLC


Sources for this article include the book titled Exterior Home Repairs published by the Handyman Club of America

12301 Whitewater Drive

Minnetonka, Minnesota 55343


Note: the patent mentioned in the first paragraph is patent number 641,543 issued by the United States Patent and Trademark Office on January 16, 1900.



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