Fiberglass Exterior Doors-What you can't see!

October 12, 2017

A new fiberglass exterior door can add not only monetary value to your home but curb appeal and increased energy efficiency as well. There are many different styles and designs available but what you may not know about are the differences you can't see visually.

In fact, what's inside is just as important as what's outside. Maybe even more.

The construction of a fiberglass door is important for the longevity, durability & security of the door. Not all fiberglass doors are made the same so it is important to understand the construction of the door before you buy one.

Most fiberglass doors are constructed in a similar way. They have the fiberglass skins or molds which can either be a smooth or wood grained. The doors are then filled with energy efficient foam which is one reason why fiberglass doors provide a high level of energy efficiency and comfort.

One of the most significant differences in construction between different types and brands of fiberglass doors are the wood construction within the door. Because Fiberglass doors are essentially fiberglass skins filled with an energy efficient foam material they need structural support around the edges of the door called rails and stiles. These wood structures are what give the door it’s stability.  

Many popular manufacturers of fiberglass doors offer several categories or lines of fiberglass doors to fulfill different price points and budgets. For example, both Provia & Therma Tru offer 2 different levels of fiberglass doors.  Provia Signet Collection & Therma Tru Classic Craft Collection are considered the "premium" lines where as Provia Heritage & Therma Tru Fiber-Classic and Smooth Star are more cost competitive lines. It is important to note that even these cost competitive lines are still fully custom door lines which should not be compared to "off the shelf" fiberglass doors from a big box store.  



Lets look closer at the "Premium" door lines and their construction.  Both the Provia Signet Collection and Therma Tru Classic Craft Collection have full wood stiles along the sides of the door and wood or composite rails at both the top and bottom of the door.  This is an extremely important feature of a fiberglass door.  As mentioned above, these solid hardwood stiles and rails provide structure, stability and support for the door.  Although construction between the two different manufacturers differs slightly, the end result is consistent.  These doors are built for durability & longevity. 



*Note:   These images show the "guts" of a Provia Signet Collection Fiberglass Door.  

The "stiles" or edges of the door are 2 5/8 finger-jointed, 3-ply hardwood which provides superior structural support. In the picture below you can see the dovetailed joinery in the Rail (top of the door) of the door which provides a strength in the frame. 










*Note:  This image shows a cutaway of a Therma Tru Classic Craft Door.  This door is constructed with hardwood stiles through the entire length of the door and composite rails (top & bottom of door). 










Both the Provia Signet Collection Doors and the Therma Tru Classic Collection doors come standard with high-performance composite bottom rails to prevent moisture penetration and subsequent rot. 




Most fiberglass door companies offer a more cost competitive line of doors and one way they can keep costs down are to alter the "guts" of the door.  An example of these fiberglass doors are Provia Heritage Collection or Therma Tru Fiber-Classic or Smooth Star Collection.  As you can see below, these doors have narrower rails and stiles than the “Premium” line.  You can see below how they have reinforced the lockset area with a wood block to add structure and support for that area vs. the premium collections which are solid wood along the entire edge of the door encompassing the lockset and hinge locations.



*Note the difference in Stiles: The Provia Heritage Collection fiberglass door (image to the left) has 1 7/8, 2-ply solid oak laminated stiles on both edges of the door vs. The Provia Signet Collection above with the 2 5/8 finger-jointed, 3-ply hardwood.    The Therma Tru Fiber-Classic door below offers a narrower stile as well with the reinforced lock block. 

















Although thinner, both the Heritage and Fiber-Classic & Smooth Star Collections come standard with composite rails to prevent moisture penetration and subsequent rot. 


Another notable difference in the premium fiberglass doors is the thickness of the fiberglass skin or mold. Many of the cost competitive doors have fiberglass skins 50% thinner than the premium skins.

The actual construction of the fiberglass door is just one of the components that affects the price or investment of your new fiberglass entry door.  

Would you like even more information about fiberglass exterior doors including how much they typically cost?  Download our Free "All About Front Doors" Ebook.  This content rich Ebook provides much more detail and information about not only fiberglass doors, but wood, aluminum clad/wood and steel doors as well.  

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