Why I Like Fiberglass Doors

Hi there…Richard The Door Guy here,

I frequently get the question: Why should I get a fiberglass door? The most important reason is durability. Now, I’m an old wood guy but you just can’t beat fiberglass doors for holding up.

Traditional wood doors are usually constructed by making a wood framework and assembling it around beveled wood panels that are slid into the frame during manufacture. Because these panels expand and contract with heat and moisture they are designed to “float” inside the framework. This means that there are joints all over the door that are potential points of water and air intrusion. Compounding the problem is that most of the production douglas fir doors are manufactured using very thin veneers as the top visible layer on the doors. This is OK if the door is not exposed to the elements but if it gets sun and especially rain Those joints will start failing and the veneers will start peeling in a very short time.

In contrast, fiberglass door surfaces are moulded so that they don’t have any joints on them. There are no joints or veneers. The skins are made from a liquid fiberglass product that is poured into a mold. Those vertical lines that you see on each side are an aesthetic addition to give the painters a stopping point when they brush in different directions. The tops and bottoms and even the side pieces of many of these fiberglass doors are made of a non-rotting composite material that will out perform wood for many years.

Fiberglass doors come in all of the same styles as the wood doors. The raised panel and moulding areas have crisp corners and step details, much like you would see in a real wood door.

The basic panel fiberglass doors are the same or less in cost than comparable wood doors.

There are probably more glass designs available, especially from ThermaTru, than there are in wood doors. Styles range from clear glass to traditional bevel glass to very modern angular styles.

Typically, the larger the decorative glass panel is, the more expensive the door will be.

Another benefit of fiberglass doors is that they are energy efficient. They have a very dense industrial foam filling inside them that slows heat and cold transfer. They usually qualify for energy star rebates offered by your state or the federal government. When properly installed they will help keep your house warmer in the winter and cooler in the summer.

As far a security goes I believe that the durable fiberglass surfaces of these doors combined with solid wood blocks in the lock installation area will make these doors just as secure as a wood panel or solid core door. I am looking for testing to back up this belief up or prove me wrong…Have not found it yet but I will let you know results as soon as I find them.

One of the most important features of fiberglass doors is their warranty. Depending on the manufacturers these doors are guaranteed for at least twenty years. Some carry a lifetime warranty. There are limitations of course but consider that most typical wood doors are warranted for just one year. Less if the rep comes out and sees that you have excessive sun or rain and an overhang that doesn’t match their formula. A typical four to six foot overhang is not enough to be considered sufficient for door and therefore warranty protection. I have installed fiberglass french doors on the back of two story houses with direct sun and rain contact and no overhang. After six years I went back to do some other door work for the folks and checked out my french doors….They looked as good as new!!

One limitation on fiberglass door warranties that should be noted: While the doors are warranted for twenty years or more, the glass inserts are often only guaranteed for ten years. It varies from different manufacturers from ten up to lifetime but it is worth noting. Still a vast improvement over wood door guarantees.

All fiberglass doors can be painted just like wood doors. According to the manufacturers, ThermaTru and Plastpro and Jeldwen, their smooth paintable lines are ready for top coat…You don’t even have to prime them. They look great painted.

You might be tempted to buy a steel door instead of fiberglass. They are usually a bit cheaper and just as energy efficient and carry the extended warranty that fiberglass does but they can dent and will rust if the finish is damaged by scratching or chipping. The steel surface will absorb heat and could be hot to the touch in direct sunlight. The manufacturing process is stamping rather than moulding. This means that the corners and raised panel areas will have more of a rolled look and not be as crisp as fiberglass doors.

Most of the companies offer a stainable fiberglass door. ThermaTru ClassicCraft is their top of the line door. They have doors that can be finished to look like real wood. Oak, mahogany, rustic styles are just a few that they offer. The rustic doors even have knots and distressing built in to give them a very realistic appearance. When you are standing there looking at a prefinished door you will be hard pressed to know that it is fiberglass. The look is amazing!

Last year I installed a pair of prefinished fiberglass pair of doors with genuine mahogany jambs and trim factory stained to match. You would be hard pressed to tell the difference between jamb and door. These top of the line doors can get very expensive. ThermaTru offers a more moderately priced stainable door in their FiberClassic line. They have an embossed oak style grain that stains up nicely but they are not as finely detailed or as realistic as the ClassicCraft. They are also not as expensive!!

A word of caution about staining fiberglass doors: Because they are fiberglass and not porous they do not absorb stain the same way that a wood door does. When finishing a wood door you apply stain and let it soak in for a bit and then wipe off the excess for a nice fairly even color. Since fiberglass doors do not absorb stains, if you wipe off the excess you will wipe off most of the color. You have to leave some of the stain in place on the door to get the depth of color that you are seeking.

It is much like applying a faux finish. You wipe it on smoothly, avoiding lap joints and leave the stain to dry on the door. After it is dry you would apply a minimum of two clear top coats to protect the door and stain surface. The more coats of finish that you apply the better deep appearance you will achieve. If you are not a patient person familiar with this type of work you would probably be better off hiring a professional finisher to do the staining for you so that you will get a quality job that you will enjoy over the years.

There are times that I will recommend a quality wood door. If the door has to match existing wood finishes, trim or sidelites and has plenty of weather protection I would say sure, choose a wood door. Oftentimes factory made hardwood doors are made without the thin veneers that I was describing earlier. If they are well made and finished properly they should give years of good service. A wood door will have more natural color variations then a fiberglass door. This is a feature that can push the decision in either direction depending on the overall architectural look that you are trying to achieve.

As I said earlier-I am an old wood guy (been doing this kind of work for almost forty years!) but you really can’t beat these fiberglass doors for holding up. The great warranties, energy efficiency, styles available and comparable costs help many people make the decision to buy fiberglass for the exterior doors of their homes and offices.