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Fiberglass and steel doors are alternatives to wood doors for exterior entryways. Both are secure, durable, and available in a wide range of designs. Despite being made of different materials, fiberglass and steel doors share more similarities than differences.
Learn about fiberglass versus steel doors and which is right for your home's exterior entryway.
Similarities
Fiberglass and steel doors are the most common exterior entry door choices, even above wood doors.
- Easier to maintain than wood
- Smooth or wood-grain appearance
- Built with insulating cores
- Available in many styles, colors, and finishes
- More energy efficient than wood doors
- Secure against forcible entry
- Impact-resistant
- Insect proof
- Available with glass inserts
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Differences
The cladding is the main difference between fiberglass and steel doors: either molded fiberglass or steel sheeting. All other differences—durability, expense, moisture absorption—stem from the difference in cladding.
Fiberglass Doors
- Clad in molded fiberglass
- More expensive than steel
- Finer wood grain detail
- Cooler to the touch
- Longer warranty
- May absorb moisture
- Cannot be dented
- Can be chipped
- No corrosion
Steel Doors
- Clad in steel sheeting
- Less expensive than fiberglass
- Minimal or no texture
- Hot to the touch
- Shorter warranty
- Will not absorb moisture
- May be dented
- Chip proof
- May rust
Construction
Fiberglass and steel doors are manufactured similarly. A wood perimeter frame is sandwiched between two thin skins of either fiberglass or steel.
The void in the wood frame may be filled with injectable high-density foam (which cures to form a stiff core), rock wool insulation, or cardboard honeycomb.
- Fiberglass doors: Fiberglass covers both sides of the door as a veneer. For wood-look doors, the fiberglass skins are molded from real wood. Fiberglass is a blend of glass fibers and resins.
- Steel doors: Steel doors are made of a wood frame covered with thin steel cladding. The steel can be roll- or press-molded to create deep bevels or it can be left smooth.
Appearance
Both fiberglass and steel doors are available in smooth or wood-grain appearances. Fiberglass doors duplicate the look of wood more carefully than steel doors since the fiberglass skins are molded from real wood.
Steel doors can present more of an industrial or contemporary look. They can look like wood, but mainly because of their coating and not because of texture.
Security
Fiberglass and steel doors are equally secure against forcible home invasion.
Steel doors are no more secure against forcible entry than fiberglass doors. When most intruders force a door open, it is by a hard kick that breaks the wood door jamb. The intruder does not break through the door itself.
Tip
The best way to keep an entry secure is with a solid door that has no glass inserts. Add a deadbolt lock, too. The best deadbolt locks, certified as Grade 1, are made of anti-drill metal and are difficult to pick.
Insulation
Fiberglass and steel doors are similarly insulated with polyurethane foam or rock wool. As long as the door does not have a glass insert, insulation values range from R-5 to R-6.
Fiberglass and steel doors have five times more insulating value than wood doors of the same size.
Heat Absorption
While both fiberglass and steel doors resist thermal transfer due to their insulating cores, steel doors tend to conduct more heat on the outside, especially in direct sun.
Steel doors on their exterior side absorb heat and can feel hot to the touch, especially when painted in darker colors.
Installation
Fiberglass and steel doors are installed in generally the same way. Both types of doors are available in pre-hung or slab form. Pre-hung doors are door slabs that are already attached to the door frames by hinges.
The slight weight difference between fiberglass and steel doors may make a difference in installation. Steel prehung doors are about 25-percent heavier than fiberglass prehung doors.
| Door Type | Weight |
| Steel door, prehung | 52 pounds |
| Steel door, slab | 45 pounds |
| Fiberglass door, prehung | 40 pounds |
| Fiberglass door, slab | 37 pounds |
- For a 36-inch by 80-inch door
Durability and Maintenance
Fiberglass and steel doors have long lifespans if well maintained. Unlike wood doors, they will not shrink, warp, split, or crack.
- Fiberglass doors: Fiberglass doors may scratch or chip but will not dent or rust. If an uncoated fiberglass door is exposed to the sun for long enough, it will eventually deteriorate.
- Steel doors: Steel doors may scratch, dent, or rust, but they will not chip. Sun exposure will not affect steel doors.
Cost
Fiberglass and steel doors both are less expensive than wood doors. Steel doors are less expensive than fiberglass doors by an average of about $900. Prices differ by about $100 on the low end and $1,700 on the high end.
| Door Type | Average Cost | Low Cost | High Cost |
| Fiberglass Door | $1,450 | $200 | $2,700 |
| Steel Door | $550 | $100 | $1,000 |
Sizes
Fiberglass and steel doors are available in generally the same size options.
Most entry doors are 36 inches wide, though some can be as narrow as 30 inches. Most doors are 80 inches tall but can range up to 96 inches tall. The thickness is 1-3/4 or 1-3/8 inches.
The Verdict
Fiberglass and steel doors are similar in terms of security, durability, energy efficiency, and maintenance. Either type of door is an acceptable wood door substitute for a new or remodeled home
Choose a fiberglass door for a more traditional appearance. Choose a steel door for a utilitarian or contemporary look, especially for mid-century modern homes.
Top Brands
Major manufacturers and suppliers of fiberglass and steel doors include:
Frequently Asked Questions
What is the best type of door for a home's exterior?
The best type of door for a home's exterior depends on style desires, budget, and maintenance and durability needs. Fiberglass doors can simulate real wood doors, even the exact wood grain. They cannot be dented, though they are liable to chipping. Steel doors are prone to scratching and denting but not chipping. Fiberglass doors are generally more expensive than steel doors.
Do fiberglass doors get hot in the sun?
As with any exterior door, fiberglass doors can get hot in the sun. However, fiberglass doors provide better insulation against solar heat than natural wood doors. Also, their outer surface becomes less hot to the sun than steel doors.
What is the life expectancy of a fiberglass door?
The life expectancy of a fiberglass door, even when poorly maintained, is greater than that of a natural wood door. However, a fiberglass door should be guarded against chipping and cracking and kept regularly painted. If well maintained, a fiberglass door should last 25 to 50 years.
Read the original article on The Spruce.
