Fiberglass or Steel Doors: Which Wins in Durability?

1. Introduction

Fiberglass doors present many advantages. Unlike steel, fiberglass is less likely to dent since it is a smooth surface. It is also more resistant to the everyday wear and tear. With a realistic wood grain texture, it is difficult for one to tell the difference between a wood door and a fiberglass door. A door made of fiberglass is able to provide the security and durability of steel and wood doors, without the maintenance. A more durable finish is only another added benefit. This being said, the value of a fiberglass door can be considered as the balance between the pricing of steel doors and the high-end wood doors.

Steel doors are known for their security related benefits. The construction of the doors is such that they are tough and not easily broken down. While the durability of steel doors is not much of a question, the appearance and maintenance can be. Steel doors are dented quite easily and may not be considered suitable for a rental property. Ugly dents in a door could be considered damage in today’s market. It may be difficult to replace the door and frame, since a pre-hung steel entry door can weigh 80 pounds or more and the dimensions may not even be standard. Pricing of steel doors may also not include the hardware which is a separate cost. High maintenance is required to prevent rust damage to the door. If the door does get damaged and it is not promptly repaired, the owner may be faced with the task of a full replacement. Pricing of steel doors can be considered relatively low over the long run, but does it provide the same value as a fiberglass door?

Durability is an important product feature for entry doors. One of the primary reasons to purchase a door is to provide security to a home. Given that, the strength and durability of the door are critical. Almost all of the warranty claims on entry doors are for damage to the finish. Since fiberglass doors often come with some form of warranty against the finish, this may be more of a maintenance issue than a durability issue. Durability can also be equated to the lifespan of the product. Assuming that the door is properly maintained, one would expect it to last long enough to justify the cost.

1.1. Importance of door durability

Maintaining the door in such a state can be bothersome, and sometimes people have a tendency to just purchase a new door. Steel doors have a stronger frame than wood doors, so they provide better security. The typical steel entry door is very cost-effective because it provides durability and energy efficiency at a price that’s hard to beat. In recent years, steel doors have been hard to differentiate from wood, considering their resemblance and low cost in comparison to fiberglass and wood doors. A steel entry door is the down-to-earth practical choice for an entry door that provides good performance and a reasonable price.

Entry doors must withstand the vagaries of temperature and weather. Steel doors are often embossed with designs, giving them a stylish yet hardy look. Primarily for the cost, a steel door is the chosen type of entry door, and now many are made so they are visually appealing. People may, for once, believe that it is mapped inside, for a steel door could mimic the look of an exterior wood door to an astonishing degree. However, in case these doors receive a bump, often times there can be a dent left in the door. Bosses and dings can often times be hard to fix and usually detract from the visual appearance of the door. Over the years, a steel door could succumb to forming rust spots. Sanding the rust spots, repairing the area with a filler, and then painting the spot can be the repair process, though this can be time-consuming.

1.2. Overview of fiberglass and steel doors

A recent study found that most homeowners prefer fiberglass entrance doors over steel doors due to the perceived looks and maintenance, but the surprising reality is that fiberglass doors may not last as long as steel doors. Vinyl is more forgiving than wood and steel, making this choice of door good for active children and pets. Unfortunately, the beauty of the door can be damaged by direct sunlight and the doors alone can cost upwards of $300. The core of a fiberglass door is usually filled with an insulating material which makes the door more energy efficient than a solid wood door. This can help offset the cost of the door over time due to savings in energy loss. This type of door is much easier to install than a wood door because it is lighter and usually can be installed by one person. The one major downside to fiberglass doors is their lack of durability compared to steel and wood, and lower quality fiberglass doors can begin to deteriorate after only a few years. Steel doors are the most energy efficient and will help lower your energy bills over time. Steel doors are the most durable door on the market but are limited on design options. High quality steel doors can continue to function and look the same as the day they were installed for several decades. This type of door is the best investment for homeowners looking for longevity and durability in their entrance doors. The downside to steel doors is once they are dented or scratched it is hard to repair the damage and they can begin to rust if the paint is cracked or chipped. There are also limited options for modifying the door after purchase.

2. Durability of Fiberglass Doors

These features add up to a door that can last an indefinite amount of time. Unlike wood doors (which peel and can warp due to the effects of weather and time) and steel doors (which can rust), fiberglass doors do not break down or succumb to the elements. Their long lifespan is also helped by the fact that they do not require frequent maintenance like other door materials. Staining and finishing every couple of years is typical for a wood door, whereas a fiberglass door will only need to be washed occasionally. Unfortunately, when considering how long a steel door will last you, one must take into account the inevitability of rust developing. Since the doors are painted and not immune to scratches, steel doors are prone to developing rust over time. Even if a particular model of a steel door claims to be rustproof, this does not apply to the cut edges (made for custom fitting) and many steel doors find themselves rusting in these areas. This is a problem that does not exist for fiberglass doors.

2.1. Strength and resistance to dents and scratches

Housepaint is the most widely used paint product for coating exterior steel doors. The finish is always smooth, high gloss, and hard. Most steel doors have a vinyl coating. If the door has been coated with an epoxy paint or a latex and oil-based paint, the finish will be smooth. At Pease, we always use exterior grade oil-based paints in 2-3 coats. This method provides a much tougher finish compared to housepaint. Fiberglass doors are the only other option, and it is impossible for the paint finish to last a long period of time. Fiberglass doors can be recoded and their color changed easily. This process requires the existing coat of paint to be removed by sanding. The surface is then wiped down with an appropriate solvent and coated with new paint. The finish of the door will be duller than its original finish but last longer than the first coat.

When it comes to strength and resistance to dents and scratches, steel doors are known to be the strongest option, but the evidence surrounding fiberglass doors is substantial. Fiberglass doors are known to be tougher than hollow-core, made of wood doors and have shown to withstand minor bumps and nicks, which would likely cause irreparable damage to a wood door. A recent study has been conducted and the evidence suggests that fiberglass doors can resist moderate to large impacts and not sustain damage. Although steel doors are known to be the toughest option, they are susceptible to denting, which is shown to be quite difficult and often impossible to repair. In comparison, fiberglass doors can resist major impacts, are much less likely to incur any kind of damage, and any damage sustained can be repaired at a lower cost. Steel doors will often incur rust spots and dents over time, and if these are located on its surface, it will often be difficult to repair the damage and restore the door to its original condition.

2.2. Resistance to warping, cracking, and rotting

Another important aspect of durability for entry doors is their resistance to warping, cracking, and rotting. This is an area in which fiberglass entry doors prove to be superior to steel doors. As mentioned above, steel doors often have only wood edges. As a result, water infiltration can cause warping, rusting, and deterioration of the wood. The net result is damage to the thermal seal, and thus a much greater possibility of air and moisture penetration. This can cause a range of problems for the homeowner, ranging from a substantial increase in utility bills to internal condensation on the windows, and damage to the structure of the home. It is also worthy to note that steel doors with wood edges require regular maintenance to prevent the onset of such problems. Painting and/or finishing the door every 2-3 years can be a real burden for the modern homeowner. Failure to do so can cause the doors to deteriorate at an alarming rate in comparison to doors with a full-length composite frame. Steel doors are also prone to scratches and dents which can expose the door to the elements and greatly expedite the process of rusting. Once rust has begun to form on a steel door it can be very difficult to stop, even with regular maintenance and treatment of the affected area. Failure to do so can result in the homeowner the need to replace the affected door. In stark contrast, fiberglass doors are not subject to these problems and are virtually maintenance free in this regard over their lifespan. Due to their ability to withstand the onslaught of the elements, maintain energy efficiency, and resist wear and tear, fiberglass doors have a durability edge over steel doors.

2.3. Longevity and low maintenance requirements

There is more to those doors than just the slab. Entry systems – which include the jambs, weather stripping, sill, and the door itself – can account for 40 percent of your home’s air leakage, particularly if the original equipment was of poor quality. This is where fiberglass doors have a clear advantage. When the performance of one material is compared to another, it is usually in terms of energy efficiency, scratching or denting, and compression and impact resistance. In each case of comparison between steel and fiberglass, the test results are essentially showing that fiberglass performs as well as steel, but with some added benefits. This is good news for people who wish to eliminate the maintenance hassles of wood and steel doors but are concerned that fiberglass might be an inferior material. The results provide solid evidence that fiberglass is a logical alternative to steel and wood.

Fiberglass doors offer a compelling mix of low maintenance requirements and high durability. Unlike wood, which needs regular painting and varnishing to stave off the effects of age and weather, fiberglass is relatively low maintenance. This is also true of steel doors, unless dents are considered to be high maintenance. Both steel and fiberglass doors resist shrinking, swelling, and warping. As far as energy efficiency is concerned, the materials are comparable. The major difference is that fiberglass is a better insulator than steel. Usually, the more insulation the better, but a door can be over-insulated. This is rarely a problem. It’s an advantage for fiberglass that it is not a very good conductor.

3. Durability of Steel Doors

The durability and toughness of steel doors are their most important attributes. Durability can be defined as the ability to withstand wear, pressure, or damage. Toughness is the ability to absorb energy without deforming. In tests conducted by the Door and Access Systems Manufacturers Association (DASMA), steel doors showed far superior durability and toughness compared to both fiberglass and wood doors. In fact, steel doors are the only type of entry door that should be insulated with foam insulation to increase durability. Steel doors have either a solid core or a honeycomb type construction to increase durability, depending on whether it is an entry, patio, or storm door. Fiberglass doors are made with a fragile and lightweight construction to reduce vulnerability to warping and busting that can occur with other materials. This leaves them with less durability and toughness than both steel and wood doors. Durability and toughness for fiberglass doors is further decreased if they are intended for entry door use, having laminated or plywood reinforcement. This is because it will eventually lead to water or moisture intrusion, and has little resistance to rust or delamination. Steel doors are also the most resilient to force and impact. This makes them a safer, more secure door to have in your home. Steel doors also resist shrinking and swelling with humidity. This prevents the warping or rotting that can occur with other doors, especially when they are exposed to harsh weather. Because of these attributes, steel doors can be described as low maintenance and have a long service life, which are discussed in the next two sections.

3.1. Strength and impact resistance

Any substances will change state (deform) when enough force is applied. By the definitions of strength and impact resistance, a strong material should be one that can undergo great forces without deforming, while an impact resistant material is one that can withstand impact without marring the surface. Steel doors are, without question, the stronger of the two. The nature of the material is such that steel can undergo much higher forces than fiberglass before deforming, and several times more than that before breaking. This does not mean that fiberglass doors are weak; they are just not as strong as steel. Studies have shown that fiberglass doors can withstand a comparable level of force to that of many steel doors. This by no means indicates that fiberglass doors are equal in impact resistance to steel doors. Faced with an impact of a given force, a steel door will dent, but only very slightly. Fiberglass doors will not permanently deform, but the result of the impact will be a major reduction in the impact resistance of the affected area. There have been instances of an area of a fiberglass door being shattered upon a relatively minor impact, though the rest of the door remained unmarred. An impact of any given force will do less immediate damage to a steel door than to a fiberglass door of comparable quality. The only way to restore the damage to a fiberglass door is to replace the entire door. Steel doors can be repaired by pounding out the area until it is level. A common method of gauging the impact resistance of a door is to test how well it can survive the barrage of a hard hit line drive and the resulting impact of a body hitting the door while falling onto a knee. If your home is in an area prone to random vandalism or has children that play with hard flying toys, roughhouse or are simply clumsy, the results of this test may be of great concern to you. Steel doors tend to be between two and three times stronger in impact resistance than fiberglass doors. While this may be of small concern in a low-risk neighborhood or a home that is not being lived in long term, people living in high-risk areas or those with a number of kids will likely find the extra strength to be a big advantage.

3.2. Resistance to warping and rotting

Due to the vulnerability of wood to warping and rotting, it is clear that in comparison, steel doors provide a more durable and longer-lasting standard of performance. This is important not only in maintaining the appearance and functionality of the door itself but also to prevent having to make premature replacements of doors due to damage, an expense which can be quite significant for doors of higher quality and craftsmanship.

Since steel is a more dimensionally stable material than wood, it does not warp as easily when exposed to temperature and humidity changes. Testing carried out by Therma-Tru Doors has shown that after 9 years of exposure to the elements, steel doors had negligible changes in dimension from their original state, better than any wood door alternative (Therma-Tru). Furthermore, if finished or primed correctly with a suitable paint, steel doors are more resistant to the effects of moisture compared with wood. This is due to the fact that the paint surface is a barrier to the elements and therefore steel doors provide a better defense against rust and corrosion that can occur from prolonged moisture exposure as well as preventing growth of fungi on the door’s surface.

One of the most insidious ways that doors constructed from wood can fail is as a result of warping and rotting. Warping of doors occurs as a result of gradual deformation of the wood from forces such as temperature changes and humidity. As wood is a more reactive material to temperature and humidity changes than steel, it is more likely to change shape if exposed to these conditions. Wood rot occurs when the surface of the wood becomes decayed as a result of fungal growth. Fungi and other microorganisms can survive off wood, eating away at it over time. Many species of fungi require a wood moisture content of more than 20% before they can begin to grow, so wooden doors in damp or humid climates are particularly vulnerable. Gurcharan Dhillon (2008) states that 35% of damage to wooden doors occurs due to fungal decay.

3.3. Longevity and maintenance considerations

Both steel and fiberglass doors are known for being low maintenance options for the homeowner. In a pre-existing home, the low surface area of the door will not necessarily require a full system replacement. However, an entry door system is meant to protect your home from the elements and provide security; therefore, homeowners are often better off changing out inefficient doors sooner than later. There is little maintenance involved with either the fiberglass or steel entry door. The two doors need to be cleaned periodically, hosing them down and using a sponge and mild detergent to combat any scuff marks or dirt. From a maintenance standpoint, the clear winner is the fiberglass door. A high-quality fiberglass door is durable and can last many years with little maintenance. It is easily refinished or repainted to change the look of the door, though factory finishes will often outlast field-finished doors. Steel doors, on the other hand, are primed and painted from the factory and they offer a decent finish but it is not as durable as the fiberglass door. Usually, a steel door will need a new coat of paint every 2-3 years to combat the effects of chipping and weathering. If the door does start to show signs of rust or delamination, it can be difficult to refinish a steel entry door. High-quality steel doors may last as long as the home, but many consumers are not willing to keep the same front entry door for 20+ years.

4. Conclusion

Consumers typically opt for a fiberglass entryway when they want to upgrade the appearance of their home. This material allows for more design options and is typically more stylish than a steel door. Homeowners who would prefer a low maintenance, long lasting door, which offers great security and energy efficiency should consider a steel entry door. Steel doors provide the best return on your investment in comparison to the alternative materials. As stated by Robert Dunn, a construction manager with Habitat for Humanity East Bay/Silicon Valley, “Steel doors are still number one when it comes to securing homes, and they’re much more affordable than wood doors.” High quality steel doors often include details such as energy efficient cores and high performance compression gaskets. Though it depends on the door and location it is being used, most building professionals have a preference of installing fiberglass doors due to the easier installation. “Fiberglass is typically about 25 percent quicker to install because they are lighter and often require no special hardware,” says Michael Collins of Riverside Construction in Tennessee. He also added that he gets more compliments from homeowners on the stylish look of fiberglass doors, and fewer complaints. Although steel doors might require additional maintenance to keep them from rusting, the ongoing maintenance for both types is very minimal compared to the maintenance needed for wood doors.

4.1. Factors to consider when choosing between fiberglass and steel doors

Factors to consider when choosing between facade material: Cost is very important when considering what material to use for a door. Some steel doors are a lot cheaper than fiberglass doors, but there are more things to consider when looking at which is the most cost-effective in the long run. Steel doors can be a lot less maintenance than a fiberglass door where weather is a big factor. If a steel door is dented, it is very hard to fix it without causing further damage to the door. In most cases, the door will need to be replaced. If the dent can be fixed, it isn’t something that the average homeowner can do without damaging the door further, so a professional’s experience would be needed. Steel doors can also rust. To prevent rust, it would need to be primed, painted, wiped down regularly, and/or powder coated. If damage to the door is cosmetically critical, repairs would need to be done immediately to prevent exposure of the metal to the elements. Failure to maintain the door voids the warranty. Prices range greatly with steel doors; at the lower end of the spectrum, there’s regular unfinished steel that runs between $150-$400 and will need to be painted. High-end steel doors can range from $500-$1500 and many still require a fair amount of maintenance. If a cheaper steel door is what the homeowner is after, depending on the cost of maintenance, a fiberglass door might be a better alternative. A fiberglass door can be the most cost-effective door in terms of maintenance. High-quality fiberglass doors with jambs, a composite adjustable sill, and high-performance hinges and locks can range from $500-$1000.

4.2. Expert opinions on the most durable door material

The industry’s two best experts on door durability, the American Architectural Manufacturers Association (AAMA) and the Steel Door Institute, recommend basing the choice of door material on the trade-offs between steel and fiberglass rather than buying into the commonly held belief that one material is superior to the other. The AAMA’s years of product testing and research have led it to one simple conclusion: both steel and fiberglass entry doors are reliable, well constructed, and very good performers. The association goes on to say that the only major difference between the two is that while fiberglass is beginning to take over the entry door market because of its success in mimicking the original beauty of wood, steel entry doors still have a slight advantage in overall security and durability. The Steel Door Institute agrees that today’s steel doors are by no means low quality and that the preference of one material over the other depends on the door’s intended use and the relative importance of each of the 3 door qualities (customization, energy efficiency, security/durability). This idea of evaluating preference by weighing the importance of steel and fiberglass’s various advantages means that there is no one-size-fits-all answer as to which material is superior and that the choice must be made on a case-by-case basis.

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