Stone-Coated Steel Roofing: A Cost and Buyer’s Guide

Stone-coated steel roofing was first developed in the 1960s, but the materials and manufacturing methods have improved dramatically over the last 20 years. This roofing product has become increasingly popular because it offers the benefits of a sturdy, lightweight steel roofing system with the curb appeal of more traditional roofing materials, including asphalt shingles, clay tile, wood shake, or stone shingles. This allows homeowners to get the roofing look they love with a lightweight, durable, fire-resistant, energy-efficient material that is highly resistant to some of nature's most extreme weather conditions.

Considering a stone-coated steel roof? Here's what you can expect when it comes to costs, installation, and maintenance.

At its core, stone-coated steel roofing is made from structural-grade steel, which is elastic enough to be stamped into the desired shape without cracking but strong enough to protect a home from the elements. After the shape is stamped out, the metal is dipped in an aluminum-zinc alloy coating, which protects the steel from corrosion. The pieces are then covered in an acrylic primer to help the next layers better adhere to the surface.

A tinted resin paint is then applied, which is used both to protect the material from water and as a binding agent for a thick layer of ceramic-coated stone granules that in conjunction with the resin paint provide the desired color and granular appearance of the finished product as well as resistance against sun damage. Finally, an acrylic glaze is applied to hold the stone in place, further protect the panels from water damage, and give the granules a somewhat glossy appearance.

Stone-coated metal roofing is designed to mimic the most popular residential roofing materials so everyone is certain to find something they like. Different manufacturers offer different patterns of steel shingles and tiles in different hues, so if you have a particular look in mind for your home, look around for a company selling a product with the exact appearance you have in mind. Two of the major brands in the stone-coating steel roofing industry are DECRA and Boral Steel.

DECRA carries the following styles: shake, shake XD, shingle XD, tile, and villa tile. The XD lines have a higher profile that means more shadowing to more closely resemble a thick shake or wood shingle roof. The basic tile features the U-shaped design commonly found in Mediterranean-style roofing, whereas the villa tile features the distinctive barrel shape of classic Spanish tiles. Each of these options is available in four to eight color options.

Boral Steel's styles include pine-crest shake, cottage shingle, barrel-vault tile, granite-ridge shingle, and Pacific tile. Their pine-crest shake, cottage shingle, and barrel-vault tiles resemble shake, wood shingles, and barrel-shaped tiles respectively, while the granite-ridge shingles look like asphalt shingles, and the Pacific tiles have the scalloped ridges of Mediterranean-style tiles. Their roofing products are available in four to eight color options.

Like most roofing materials, stone-coated steel roofing is priced by the square, which covers a 100-square-foot space. Generally, the materials cost between $400 and $550 per square, which includes the panels as well as the installation materials, including underlayment, flashing, trim, fasteners, and ridge caps. Installation costs are typically between $450 and $900 per square, which means the total cost after installation is between $850 and $1,450 per square.

Panel thickness also impacts the cost, with thicker 24-gauge steel costing more than the thinner 28-gauge sheets. Similarly, panels featuring higher-quality coatings in thicker protective layers will cost more but will also last longer.

The installation method can also impact the overall cost. For example, some metal roofing can be installed over existing roofing, such as old asphalt shingles, provided that the existing roof is in good condition. This is known as re-roofing, but many experts discourage this practice. The standard installation involves removing the old roofing and starting with a bare roof deck. Removing old roofing, called a tear-off, adds about $75 to $150 per square to the total installation cost.

Whether or not the roof is installed over existing roofing, wooden battens are typically used to create a grid to which to nail the steel roofing panels, but it is also possible to do a direct-to-deck "battenless" installation. The best installation option varies from home to home, but those that use battens cost $45 to $75 more per square. Your choice of underlayment will also impact the cost. You can use the asphalt-saturated felt paper typically used under asphalt shingles, which is only $5 per square, but most homeowners opt for rubberized underlayment designed to reduce noise transfer under steel roofing, which costs between $75 and $125 per square.

Stone-coated steel roofing should be installed by a roofing contractor who specializes in this material. It requires skilled and careful installation to ensure weathertightness and to prevent damage to the material. This is not a good time to save money by hiring an inexperienced roofer or attempting to tackle the installation yourself. Late summer through fall is peak season in the roofing industry, so expect to pay more if you have your roof installed during this period or during a period of cold weather when it is more difficult to finish a roofing project.

Finally, the location and design of your home could also impact the cost. If you live in an area with a high cost of living, expect to pay more for installation charges. Roofing for multistory homes typically costs 15 to 25 percent more than roofing on single-story homes due to the difficulty of getting crews and materials onto the roof. Similarly, the more steep or complex your roof (think skylights, chimneys, peaks, and elevation changes), the more difficult the job will be and thus the more expensive it will be.

The first thing you need to consider when determining how to install stone-coated steel roofing is whether you want to install the roof on your existing roof or tear off the old roof first. Installing over an existing roof can save money, but re-roofing is only possible with certain types of existing roofing, most commonly a single layer of asphalt shingles, and the roof must still be in decent condition. Re-roofing is prohibited in some areas, so always check your local building codes first.

You also need to decide whether or not to use wood battens. These are used in most installations because they add a dead space between the roof deck and the metal panels. This adds some insulating value and promotes airflow under the roofing to reduce heat gain and thereby lower cooling costs in the home.

If you live in an area prone to heavy winds, like those found with hurricanes, a battenless installation may be preferable because fastening the panels directly to the roof deck keeps the panels more securely attached to the home under heavy winds. If battens are used, you may also choose to install panel vents on the roof to further increase energy efficiency by allowing heat and moisture to escape from your attic.

Steel outperforms many other materials under hot weather since it both reflects the UV rays and provides a layer of insulation with an R-value between 2.5 and 3.39 depending on the thickness of the panels, the material style, and the installation method. Of course, most roofs will perform well on sunny days, but it's how the material does under extreme weather conditions that really determines the material's durability, and stone-coated steel roofing has high performance ratings all around.

When interlocking panels are installed directly on the roof decking rather than with battens, it can be rated to hold up to hurricane-level winds up to 120 miles per hour. In fact, DECRA has lab-tested its materials to find that they can hold up to winds even twice that speed, meaning they could even survive many tornadoes, though the warranty does not cover winds over 120 mph.

Steel also excels when it comes to impact resistance and has a Class 4 rating. This is the highest possible rating for roofing materials and means that the material can withstand hailstones up to 2.5 inches in diameter. Most steel roofing companies guarantee their roofs against damage from hailstones up to this size.

When it comes to rain, snow, and ice, the interlocking panels of steel roofing are impervious to these weather conditions, and unlike porous natural materials, such as wood, steel will not be damaged by contracting and expanding under extreme temperatures. The corrosion-resistant coatings applied to the steel sheets also protect it from corrosive, salty sea air.

If you live in an area prone to fires, you'll be happy to hear that stone-coated steel roofing has a Class A fire rating, meaning it has the highest possible rating when it comes to fire resistance. This makes sense because steel is a noncombustible material.

For all of these reasons, home insurance companies may reduce premiums by up to 35 percent for homes with stone-coated metal roofs.

Because the manufacturing techniques used on modern stone-coated steel roofs have only been in practice for around 20 years, it's impossible to say with absolute certainty how long-lasting these products will be. That being said, based on lab tests by the manufacturers, the life span of previous incarnations of stone-coated steel roofs, and the long life of other types of metal roofing products, these are almost certain to survive at least as long as the manufacturers' standard 50-year limited warranty and possibly even longer.

There are a lot of benefits to stone-coated steel roofing, including its long life span; ability to hold up to the elements; and versatile, attractive appearance. Some other advantages include:

• It is lightweight, which is why it can be installed over existing roofing. Stone-coated steel roofing weighs around 150 pounds per square, whereas asphalt shingles can weigh anywhere from 195 to 425 pounds per square depending on the quality. Clay and concrete tiles can weigh 600 to 1,500 pounds per square, and slate can weigh anywhere from 700 to 3,000 pounds per square. This is why tiles and slate often require roof structure reinforcement before they can be installed.
  
• Metal roofing can protect your home from earthquakes since the lightweight, sturdy material can strengthen your roof assembly to better withstand tremors. This is a stark contrast to heavier materials, such as clay or concrete tile, that add significant weight to the top of your home without increasing its structural integrity.
• Steel can improve a home's energy efficiency. With insulating abilities and UV reflectance, metal roofing can save homeowners on their air conditioning cost, and a stone-coated steel roof with infrared-blocking colors and a vented installation can reduce the heat transferred into a building by 70 percent compared to asphalt shingles.
  
• Metal roofing is recyclable and is made from recycled materials.
  
• Stone-coated steel roofing can increase a home's resale value by as much as 6 percent over asphalt roofing.
  
• It is low maintenance. Manufacturers typically suggest that leaves, dirt, and other debris be removed once a year to prevent staining.

Like all things, there are disadvantages to steel roofs as well. For example:

• Stone-coated steel roofing is more expensive than many other roofing materials. However, it is more affordable than many forms of tile, which may require a roof to be reinforced before installation, and steel roofing lasts much longer than asphalt or wood shingles and shakes.
  
• It can be noisy because metal transfers more noise than other materials, but this can be minimized with rubberized underlayment, and some people enjoy the sound of rain on a metal roof.
  
• Walking on the middle of the panels can dent them and void the warranty.
  
• Algae and mold can grow in humid climates, but these can be removed with chemical treatments.