• Door Type vs. Door Style
Storm door type could be confused with storm door style, so let me first clarify these two terms. By type is meant that which signifies a fundamental design characteristic as, in this case, how a storm door is fitted and properly attached to an entry door opening. Two distinctly different types of entry door openings exist, so two general storm door types are available to accommodate both openings.
By style is meant secondary design characteristics having to do with, in this case, the general look, layout, and appearance of the storm door, how the glass and screen install or operate, and other special features offered. Examples of common storm door style names are: Fullview, Self-storing, Security, ScreenAway, and RollScreen (the last two are trademarked names for a retractable screen feature). Scores of styles of storm doors exist to choose from, but there are only two general storm door types.
• The Z-Bar (Pre-hung) Type - More Common
Most entry doors tend to use exterior trim of the standard square-corner type, such as common 1 1/4" x 2" brick molding (or the like). Openings trimmed out this way allow for the mounting of a common "pre-hung" type storm door. This door is a door-plus-frame ensemble manufactured to fit a specific size opening and is also known in the trade as a "z-bar" storm door. This term is derived from the cross-section shape of the frame that loosely resembles the letter z. The aluminum z-bar channel frame is multi-functional: it's used to securely attach the door (with screws) to entry trim like common brick molding, it holds the weather stripping seal(s) and acts as the stop for the storm door to close against, and the usual mortise-style lockset bolt latches catch on the z-bar (through a strike attached to the z-bar) to keep the storm door closed.
Entry openings trimmed out with common brick molding (or the like) will almost always accept a z-bar door in one of the usual standard sizes (widths of 30, 32, 34, and 36 inches; height of 80-81 inches). Storm doors of all styles found "in the bin" at most home improvement stores are the more common pre-hung, z-bar type storm doors.
But not all entry doors use a standard size, square-corner trim or brick molding. This is often the case on older homes, but it's also seen in newer construction, as well. Some non-standard openings can be properly modified to allow a z-bar type storm to be installed. If modifications can be made (involving additional costs), it may be that only a custom-sized z-bar door will now fit the rebuilt opening. Many companies do offer made-to-order, custom-sized z-bar doors in various styles, but these doors will be special orders, and will cost much more (up to double) as compared to the standard size doors found in stock.
• The Expander Type - Less Common (but still a contender)
On entry door openings using round, beveled corner, or other decorative shapes of corner molding (or even square-corner molding that is too small), using the other type storm door is by far the best, and sometimes, the only, solution. This less common type of storm door is called an "expander" type, so named because it employs aluminum expander channels that slip over each edge of the storm door core. These expanders are positioned and secured on the door core so as to exactly fit the door within the existing opening. This even works on a wildly out-of-square entry opening to ensure an exact fit. An expander door doesn't have a frame like the pre-hung z-bar door has. The entry door frame (usually wood), itself, serves as the stop for the expander storm door to close against. Small profile, L-shaped aluminum extrusions hold the weather stripping material and are attached directly to the entry door frame. Quite a lot of door width and height adjustment is possible with an expander type door, whereas, no width, and very little height adjustment, is possible with a size-specific pre-hung z-bar storm door. Changes to an existing non-standard opening are rarely ever needed when an expander type storm door is used for the job.
The expander type storm door, though ideally suited for a non-standard opening, does have its minuses. Not all companies offer this type of door, and, from the ones that do, models, styles, and features are limited, not nearly the choice offered with models and styles of z-bar doors. Mortise-style locksets will not work on an expander door, only surface-style locks will work (these requiring separate strikes attached to the entry door frame/jamb), and these are usually not as stylish as the mortise-style locksets that are regularly supplied with z-bar doors. An expander door option (or expander kit) will add to the cost of this type door, and it takes more labor to install them with many more parts to cut, fit and assemble (compared to installing a z-bar door), also adding to the cost. When only an expander door will fit the bill, though, there are two expander type storm doors manufacturers I'd give the nod to.
The solid-core line of storm doors by Pella (having a particleboard core and sides clad with aluminum) are available with optional expander kits, and most of the aluminum-framed ProVia models are available as expander builds (no separate expander kit is needed). The quality of the solid-core Pella doors is high, and I have installed these on both front and rear entries. Solid-core constructed storm doors are not available in the popular Fullview style, though. If a Fullview style, expander type storm door is needed, ProVia is the only company to offer them, currently. ProVia doors may cost a bit more compared to other name brands, but these doors are unsurpassed in both construction and materials you won't find a stronger or more durable aluminum-framed storm door. See the Pella and ProVia websites (at the Door Links page) for more info.
• Fairlington and Fairlington Towne Residents - Think Expander Type
I've worked on lots of doors in Fairlington and Fairlington Towne over the years. These homes have entry openings that do not use a standard size, square-corner trim or brick molding. At the request of some home owners I have modified entry openings to accept the more common pre-hung Z-Bar type storm doors. It is my opinion, though, that expander storm doors are still the ideal solution for these homes.
On a different note, Fairlington residents with entry door questions or problems should read Fairlington Entry Doors (another DH article).
Copyright © Bill Reeves