How to choose between a fiberglass or a steel exterior door.

This article compares the properties, features, pros and cons of fiberglass and steel exterior or entry doors.

In this article series we discuss the selection and installation of windows and exterior doors, following best construction and design practices for building lighting and ventilation, with attention to the impact on building heating and cooling costs, indoor air quality, and comfort of occupants.

Steel vs Fibreglass Exterior Doors: Features, Costs, Durability

Guest Article, courtesy of Roman Tymchenko & Matan Korin, EcoLine Windows, Canada

Exterior entry doors are made with a variety of materials, but Steel and Fiberglass currently dominate the market over traditional wood entry doors. Which of the two is better?

There are many factors to consider when choosing your door material, including door durability and entry door energy efficiency.

Those variations can make choosing difficult. This simple entry door guide will help you make the right choice.

Our photo shows a steel exterior door retrofit to a 1920's home in Poughkeepsie, NY, adding security and weather-resistance to the structure.

[Click to enlarge any image]

Steel vs Fibreglass Doors: Pros & Cons

Steel Door Features

Steel doors are typically

• More Durable
• Low Maintenance
• Very Secure
• Affordable
• Energy Efficient

Fibreglass Door Features

Fibreglass doors are

• Versatile in design features such as panels, panel shapes, windows, appearance
• Rust-Free
• Low Maintenance
• Highly Energy Efficient
• Secure
• Modern (this is an aesthetic opinion and not a durability or functional feature - Ed.)

Photo above: this wood-like brown fiberglass exterior door, installed on a New York home, looks like wood, but promised durability without the need for periodic painting.

With an array of qualities that make both fibreglass or steel suitable for exterior doors, each of these two door types also has disadvantages or exposures that you should consider before making a choice.

Steel Door Downsides

The main con of steel doors is their susceptibility to rust and how prone they are to denting.

Steel doors also have a distinctive "metal" look that is, for some homeowners, less attractive due to the door's sheer weight and its monolithic appearance.

Fibreglass Door Downsides

Fibreglass doors are typically more expensive, a concern for some potential buyers.

Despite the fact that fibreglass doors are very durable, there's no competition with steel doors when it comes to strength, security, and cost.

Although fibreglass doors are less likely to dent upon impact, fibreglass doors are more prone to cracking from sun or weather exposure or from impact.

In choosing an exterior door you'll want to decide which of these door factors is more important for your building.

Which Door is More Energy Efficient: Fiberglass or Steel?

With rising energy costs, global warming, and a coming economic recession, homeowners needing to choose a door ask about its energy efficiency.

Doors are one of the most essential features to consider when it comes to efficiency, both due to heat transmission through doors and often more significant, the air tightness of the door: its leakiness.

It's vital to consider the door material and also the quality of its supporting frame including its weatherstripping.

Photo: an antique solid-wood door sporting a heavy brass entry lock.

Both Steel and Fiberglass doors outperform traditional wood doors in energy efficiency. Modern technologies and materials allow for superior insulation that makes both materials perform well for exterior doors, but does this mean they are made equal?

Almost. The difference in energy performance between a steel door and a fiberglass one is minimal: they both contain the same insulation technologies and both can offer the same insulating material, such as high-R high-density foam.

A new Energy Star-rated door (Steel or Fibreglass) would come with an average R-value of 5 to 6, a decent energy rating that will positively affect your utility expenses.

A premium residential steel door has a 24-gauge or heavier galvanized steel skin over a wood or steel frame filled with foam insulation. This creates an extremely strong and durable product with an effective insulation rating of about R-8 for polyurethane insulation versus about R-5 for polystyrene.

Generally, new exterior doors are 15% more energy efficient than any standard model.

So analyzing the energy efficiency properties of steel vs fibreglass doors, we conclude that it's a tie, though both steel and fiberglass outperform a solid wood entry door.

At INSULATION R-VALUES & PROPERTIES we include insulating R-values for WOOD materials where you'll see that wood has an R-value between about 0.7/inch (hardwood) and 1.25/inch (softwood). So a 1 1/2" thick solid wood door, considering that typically its panels are recessed, probably offers an R-value of about R-1 and a maximum R-value of about 1.4.

So an insulated steel or fibreglass door's R-value is about 5 times the R-value of a solid wood door.

Watch out: this comparison says nothing at all about air leaks at a building entry door. In our experience, if a door is leaky, that effect on the building's energy efficiency or unwanted heat loss or heat gain will far dominate the actual R-value of the door. A very leaky window or door is tantamount to leaving the door partly open!

So the quality of door weather stripping and its maintenance are important and when choosing a door, including its frame, take a close look at the quality of its weather stripping for durability as well as ease of replacement should that be needed.

Details are

at WINDOW / DOOR ENERGY EFFICIENT, DOE

Energy Cost & Environmental Impact of Steel vs Fibreglass vs Wood Doors

Really: While our discussion above compared the energy efficiency of steel and fibreglass doors, that's addressing the effect of the door on the building's energy cost over its life. It does not address the environmental impact of the production and distribution of doors by material. By that measurement, wood doors perform well, though we're not sure that all of the costs and impact of wood harvesting were reflected.

Graph: O'Connor (2009) compared the environmental impact of the production and distribution "Cradle to gate" of fibreglass, steel, and wood doors - cited in detail below

[Click to enlarge any image]

Really: Compared with fibreglass or steel doors, it's worth noting that the manufacture and distribution of wood doors remain the door material having the lowest environmental impact.

Of 44 air emissions in a study of "cradle to gate" production of doors, According to this study, steel doors create 40 times more waste, cause 27 times more greenhouse gas emission, and consume 22 times more energy. These results also show substantially more air and water pollution with steel doors versus wood.

In a study cited by O'Connor, ... a typical galvanized steel door with polystyrene insulation is considered, along with a typical solid wood door (the study actually addressed wood doors with fibreglass reinforcement at joints, however the fibreglass is omitted from the LCA because of its very small contribution to the LCA results). A summary of the results is given in Table 1. (O'Connor 2009 p. 9) (Knight 2005) (Younes 2012)

Note that some of the research cited by O'Connor in turn held the view that lifetime energy-related costs of all three door types, Fibreglass, Steel, Wood, were about the same when considering periodic repainting and glazing.

I'm not sure we agree with that smaller point, since at least the brown wood-tone fibreglass door shown above on this page has been in place for fifteen years without the requirement for any maintenance at all except for hinge lubrication.

Really: OPINION (of the editors): differences in the environmental impact of producing a building product like a wood door compared to a fiberglass door or a steel door may be significant, but might be very small compared with the building owners' choice of heating and cooling system, fuel, or the maintenance of the system, or the building's overall air leakiness or insulation scheme.

If a building's door or window is poorly sealed, the energy cost and thus indirectly the environmental impact of that poor seal over the building's life will in that case far overwhelm the environmental impact of production and distribution and installation of the window or door itself.

Bottom line: a door that fits well, seals well, and that remains that way for years will save energy and reduce the building's environmental footprint.

We discuss building air leaks and their effect on energy cost

at HOUSE DOCTOR, how-to be

at WINDOW / DOOR AIR LEAK SEALING HOW TO

and at AIR BYPASS LEAKS

Which Door is More Durable & Secure: Steel or Fiberglass?

One of the most important features of your home's exterior door is durability and security. After all, what is a door good for if not to keep people out?

You can opt for the best-looking, the most energy-efficient door on the market, but what good is this if it's easily broken into?

It's hard to look past steel doors when discussing sheer durability and strength. If this is all you care about when choosing your exterior door, then steel doors will be your choice.

A solid steel door with a sturdy lock is VERY secure, and you can rest easy knowing it's the difference between a safe and unsafe home.

This is not to say that fibreglass doors are weak. Fibreglass doors are still effective for home security, and their durability means they can last a lifetime.

Both Fibreglass and Steel doors are effective when combined with a sturdy lock, but Steel just surpasses Fibreglass in security.

Which Door Material is More Versatile: Fibreglass or Steel?

Doors are the centrepiece of your home's exterior, so it's essential to consider the versatility of styles. Both materials have design options to suit every home, but Fibreglass undoubtedly has more options.

Steel is very restricted by its texture. Finding a steel door that doesn't simply have a smooth, metal-like look is difficult, whereas fibreglass has versatility on its side.

Fibreglass doors come in a wide range of textures that enable them to mimic wood.

For many, this selling point gives Fiberglass the edge over pure Steel.

Fibreglass also offers a wider level of versatility when it comes to painting and colour. With options to stain and paint the material, homeowners can perfectly match the door with their home exterior. For this, Fiberglass wins.

Which Door Type Has More Custom Features: Steel or Fiberglass?

It's not just aesthetics that homeowners look for, but also a range of features. Doors aren't just solid panels of Steel, Fibreglass or Wood - they have various customizable features to suit every home.

Both Steel and Fibreglass have customizable features, but Fibreglass stands out as the one with more options.

Panels, particularly window panels, have more options with fibreglass doors, while customizable strips and mouldings are more common and have larger selections.

It's also worth considering that post-purchase customizations like cat/dog flaps are much more challenging to install with steel doors. For this reason, Fibreglass comes out on top.

Steel vs Fibreglass: Price Comparison

New exterior doors can be customized with different features, from the number of panels to glass inserts and hardware.

Therefore, the final quote can be only given upon discussing your preferences with a local contractor and analyzing what works best for your specific replacement project. But here is the approximate price range for both door types based on what we got from fellow window experts.

Keep in mind that the prices above are given based on a single solid door configuration. If you want to go with another configuration like double doors, steel or fibreglass doors with sidelites or customize glass inserts, the price will vary drastically depending on the number of extra features, complexity of installation and different add-ons.

If you want to analyze how the door configuration, glazing and other features influence the cost of your door replacement project, you can use ecoLine's door cost estimator (found at the end of this article) for more in-depth information regarding steel or fibreglass door prices.

Conclusion: Fibreglass Door or Steel Door?

When it comes to choosing the right material, personal needs dictate which is better.

If you need the most secure, durable, and cost-effective door, then choose a steel door.

If you need versatility and a range of different door styles, or a wood-look like the door shown at the top of this page, then it's hard to beat a fibreglass entry door.

 

Contributor

Thanks to Roman Tymchenko & Matan Korin at EcoLine Windows & Doors for contributing most of the original material for this article. (Lily N.)

Contact: ecoLine Windows & Doors, 10905 48 St SE, Unit 151, Calgary, AB, Canada, T2C 1G8, Tel: +1 (866) 351 4096 Web: https://www.ecolinewindows.ca/ Email: hi.roman.tymchenko@gmail.com

ecoLine has offices in a dozen locations in Canada in Alberta, BC, Manitoba, Ontario, Saskatchewan, and has sales representatives in other locations in Western Canada including Kelowna, Victoria and Nanaimo on Vancouver Island, and in Vancouver BC.

ecoLine provides this ecoLine DOOR COST ESTIMATOR (in Canadian Dollars) and on the same page, a window cost estimator link is also provided.

Research: Steel vs. Fibreglass vs. or Wood Doors

• Cuce, Erdem. "Role of airtightness in energy loss from windows: Experimental results from in-situ tests." Energy and Buildings 139 (2017): 449-455.
• Emmerich, Steven J., and Andrew K. Persily. "Analysis of US commercial building envelope air leakage database to support sustainable building design." International Journal of Ventilation 12, no. 4 (2014): 331-344.
• Kalamees, Targo. "Air tightness and air leakages of new lightweight single-family detached houses in Estonia." Building and environment 42, no. 6 (2007): 2369-2377.
• Knight, Lynn, Melissa Huff, Janet I. Stockhausen, and Robert J. Ross. COMPARING ENERGY USE AND ENVIRONMENTAL EMISSIONS OF REINFORCED WOOD DOORS AND STEEL DOORS [PDF] USDA, Forest products journal. Vol. 55, no. 6 (June 2005): Pages 48-52. (2005).
  Description:
  The USDA Forest Service Forest Products Laboratory has patented a technology that incorporates fiberglass-reinforced wood into the structure of wood doors and other wood building products. The process of reinforcing wood doors with epoxy and fiberglass increases the strength and durability of the product.
  
  Also, it allows the use of low-value, small-diameter wood which conserves mature forests and allows greater utilization of forest material.
  
  Since wood and steel are two material options for the construction of residential doors, we compared the potential environmental effects of both products (reinforced wood doors and steel doors) by conducting a partial life-cycle inventory (LCI) to compare the energy use and environmental emissions of the premanufacturing and manufacturing life stages of each product.
  
  The partial LCI analysis clearly showed that steel doors resulted in significantly more energy use and environmental emissions in all categories studied including air and waterborne emissions, solid waste, energy consumption, and greenhouse gas generation.
  
  Excerpts:
  ... steel doors have significantly higher air emissions for 36 of the 44 atmospheric emissions analyzed. Also, they produce significantly higher quantities of waterborne wastes in all 32 emissions included ...
  
  ... steel doors consume 21 times the amount of total energy (including both fossil and non-fossil fuels) and generate over 40 times the mass of solid waste compared to reinforced wood doors.
  
  In the premanufacturing and manufacturing stages, steel doors are estimated to produce 27 times the carbon dioxide equivalents produced during the same stages for the reinforced wood doors.
• New York State, RESIDENTIAL EXIT DOORS, STAIRWAYS, LANDINGS, HANDRAILS AND GUARDS [PDF] Technical Bulletin, 1 January 2003 (10 July 2003), Source Department: 19NYCRR 1220 - Residential Code of New York State (RCNYS), web search 03/03/2011, original source: http://www.dos.state.ny.us/code/pdf/RCstairsTB.pdf
• O'Connor, Jennifer. CONSIDERATIONS FOR ENVIRONMENTAL FOOTPRINTING OF WOOD DOORS [PDF] FPInnovations-Forintek, Vancouver, BC, Canada (2009): 28. Prepared for Window & Door Manufacturers Association of BC.
  Abstract:
  This is a discussion paper addressing the factors involved when considering the total environmental footprint of wood doors. The discussion is within the context of a new amendment to BC energy regulations affecting doors and the subsequent market shifts that will occur as a direct result.
  
  The energy regulation applies a U-value threshold to doors. U-value is a physical (thermal) property of an assembly indicating the rate of conductive heat flow through the assembly.
  
  A maximum U-value for doors is being specified in BC that cannot be met by the current commonly-manufactured configuration for solid wood doors. In this paper, a life cycle assessment (LCA) approach is used to discuss the broader environmental picture beyond the single criterion of U-value, specifically focusing on the trade-off between embodied energy in a product and the impact of that product on the operating energy of the building in which it is installed.
  
  Any change to the current manufacturing process for wood doors for the purpose of improving thermal characteristics should be done within an LCA perspective so that the changes don’t inadvertently lead to a net increase in total lifetime energy consumption.
  
  Similarly, any market shift to non-wood alternatives for doors should also be done within an LCA perspective for the same reason. A detailed and precise analysis of door footprints requires LCA data and energy simulation results, both of which are beyond the scope of this study.
  
  In place of full LCA data, we accessed existing literature and existing partial LCA data (from the Athena Institute) to roughly estimate the embodied energy differences between door types, and to discuss the other environmental impacts of a substitution from today’s common wood doors to non-wood alternates.
  
  Three generic door types were compared: wood, steel and fibreglass. In all the environmental metrics examined, including embodied energy, the wood doors have the lowest impact.
  
  Although insulated steel and fibreglass doors typically have a lower U-value than wood doors, they involve more energy consumption in their manufacturing. This means that the added energy investment in steel and fibreglass doors will require some time to be paid back through reductions in a home’s heating and cooling costs.
  
  Similarly, an improvement to wood doors to reduce U-value may increase the embodied energy, requiring a payback period that may or may not be reached within the lifetime of the door.
• Sherman, Max H., and Wanyu R. Chan. "Building air tightness: research and practice." In Building Ventilation, pp. 155-180. Routledge, 2006.
• Van Ooteghem, Kevin, and Lei Xu. "The life-cycle assessment of a single-storey retail building in Canada." Building and Environment 49 (2012): 212-226.
• Younes, Chadi, Caesar Abi Shdid, and Girma Bitsuamlak. "Air infiltration through building envelopes: A review." Journal of Building physics 35, no. 3 (2012): 267-302.
  Abstract:
  Air leakage through the building envelope into the building interiors has a considerable impact on the energy loads and consequently energy demand and energy costs of buildings.
  
  This phenomenon known as infiltration happens through various openings and venues in the building envelope varying from large openings such as doors and windows to minute cracks and crevices.
  
  In addition to impacting building energy loads, infiltration impacts indoor air quality and can result in moisture accumulation problems in the building envelope. A generalized review of infiltration that includes evaluation techniques and models, quantification, and interaction with other heat transfer phenomena is presented in this article.
  
  Excerpt:
  In residential and small buildings, infiltration through doors is more defined by air leakage … resulting air change rates, energy requirements, and, ultimately, costs.
  

...

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