Per Square Foot Costs by Sealant Type

There are many different types of roofing sealant, each with pros and cons. Most promise waterproofing and extended roof life (if sealing an existing roof) and better fire resistance. Some include white and reflective surfaces to reduce cooling costs while others are clear. Corrosion and chemical protection sealants are also available.

Silicone

Of all the roof coatings, silicone provides excellent durability and long-lasting weatherproofing for a price between $4 and $1.50 per square foot. It's sold as a full roof coating that often doesn't require a primer. It is used as the covering for spray polyurethane foam (SPF) roofing systems. If installing this yourself, be sure to use fabric or fibered reinforcement sheets. However, it loses its UV rating faster than most other types.

Bitumen

Bitumen costs $0.75 to $1.50 per square foot. It's an asphalt-based sealant used around flashing, skylights and chimneys on asphalt roofs. It's not used as a complete roof coating and not often used on any complete roofing membranes besides a Built-Up Roof or Modified Bitumen Roofing.

Polyurea (Polyurethane)

A relatively new roof coating, polyurea requires a primer and two coats and costs $0.50 to $2 per square foot. It has the best insulating properties of all roof coatings. It's also the most durable, suitable for high-traffic areas.

Acrylic

Acrylic is the cheapest at $0.15 to $0.75 per square foot, and the most popular elastomeric coating. However, it has a higher failure rate than any other type and will need a new coat every ten years, if not sooner. Excellent for DIY applications and short-term coating and sealing needs.

EPDM

Liquid EPDM creates a monolithic roofing system as opposed to EPDM sheets that create seams. Use it on almost any roofing type with the right primer. EPDM is generally thicker than other types of roofing and cost about twice as much at $1.50 to $2.50 per square foot. However, it often only needs a single coat.

Calculating Costs by Roof Slope

The Roof Coatings Manufacturers Association, along with many contractors, recommend coatings for flat and low sloped roofs. Pitched roofs should use tiles or shingles where no coating is necessary.

Flat Roof Coating

Flat roof coatings will cost between $0.15 to $2.00 per square foot for materials and an additional $0.50 to $3.00 per square foot for labor as broken down in the cost per square foot section above. This price is for a coating over a pre-existing roof system, such as a rubber membrane or metal roof.

Pitched or Sloped Roofs

Most pitched roofs are asphalt shingle or tile where complete coatings are not recommended. However, there are some exceptions and considerations when dealing with a pitched roof.

• Metal: such as in residential settings, can use an elastomeric coating for corrosion resistance or just to extend the life of the roof. You'll usually pay an additional $1.00-$2.00 per square foot since the coatings must be applied in multiple thin layers.
• Asphalt Roll: For small leaks and tears, elastomeric bitumen sealants run between $15 to $20 per gallon or about $6 to $10 per 10-ounce tube. Use repair fabric in conjunction with these sealants. Fabrics will cost about $10 for a 25-square foot roll.
• Asphalt Shingle: Only use bitumen or elastomeric sealants around flashing, vents and skylights. Using complete coatings on asphalt shingles is a short-term fix and may actually do more harm than good. Repairing or replacing your damaged asphalt shingles is the long-term solution. Replace any underlayment and damaged roof sheathing as well. Considering that installing a new asphalt roof costs an average of $3,700 and a new tile roof costs an average of $11,500, the price of repairing asphalt shingles as a solution is well worth the investment.

If you're still set on coating shingles, you may want to try one of these options:

• Envirosafe Shingle Roof Coating: $230 per 5-gallon pail. It comes in a variety of colors with a 10-year warranty.
• Armor Shingle Roof Coating: $380 per 5-gallon pail that claims a breathable but waterproof layer. It has a clear finish and will cover approximately 1,250 square feet.
• Membrane Style: is fairly rare to find on a pitched roof, but not out of the question. Depending on the type of material it's made from, you can install a complete coating to rejuvenate and seal your roof. Your current roofing material will determine the type of coating you'll need.

Calculating Costs by Material and Type

There are a few considerations to take into account that depend on the type of roof you currently have. Whatever type you have, be sure to seek advice from a qualified specialist who works specifically with the material. Not all roofing contractors work on all types.

Polyurethane Foam Roof Coating (SPF)

Polyurethane foam roofs are one the best options for flat roofs. Part of a polyurethane foam roof is the topcoat, usually a silicone membrane. You'll probably want to recoat or seal your silicone roof with another coat of silicone for $1.50 to $2.50 per square foot, including labor. Verify what type of coat your roof currently has as various coatings do not always adhere to each other.

Metal & Aluminum Coating

Metal roofs are for flat, low slope and pitched roofs. You can apply almost any type of coating to a metal roof. For a pitched metal roof, expect to spend between $1.50 to $3 per square foot on labor. Depending on the pitch of the roof, the coats are applied in thinner layers. It may need more than two coats and increase application time.

Asphalt Shingle

Mechanically repair and replace all damaged shingles and underlayment. You should never need to apply a full coating to any asphalt shingled roof. Bitumen, at $0.75 to $1.50 per square foot, is used around flashing and other areas that surround the asphalt. You may use it to temporarily fix a broken or leaking asphalt shingle before you're able to replace it fully.

Concrete Tile

There is a lot of debate around sealing concrete or clay tiled roofs. Concrete is a porous material, but the pitch of the roof in conjunction with the overlaid arrangement keeps water out. There are some concrete sealants mentioned in the next section that you can apply to concrete tile, however, repairing and replacing is the recommended solution.

Sealants are usually unnecessary and applying them may harm your roof. Applying sealants requires power washing and walking on the tiles, both of which can damage your tiled roof. Speak with a professional concrete tile roofer before beginning any tile project.

Wood Shingle

Wood shingles never need any type of sealant. When wood leaks, you'll need to find the cause and mechanically fix the leak. Sealants can harm wood shingle and shake. If you have a wood roof, speak with a qualified, licensed wood roofing specialist for any repairs you need.

Estimated Prices by Brand

Common brands found in the U.S. at hardware and home improvement retail stores present a cheap solution for the competent DIYer. Your contractor is likely purchasing straight from a manufacturer from the Roof Coatings Manufacturers Associated. Here are a few of the common retail brands.

• Gaco: $0.70-$1 per square foot. They make a wide range of 100% silicone, acrylic, polyurethane, epoxy, and spray foam products for waterproofing and insulation your home.
• Henry: $0.15-$0.40 per square foot. Makes acrylic and asphalt emulsion coatings and sealants. Manufacture full roofing systems, adhesives and spray foam insulation.
• Black Jack: $0.25-$0.40 per square foot. Makes elastomeric siliconized coatings at a bargain price for a quick DIY job. Make asphalt sealant for sealing cracks, valleys, flashing and chimneys for about $15 per gallon.
• Liquid Rubber: $1.50-$1.75 per square foot. Makes 100% liquid EPDM products for thick applications. Make caulks and fabrics used in EPDM applications.
• Lanco: $0.50 per square foot. Makes a fully siliconized acrylic based roof coating for waterproofing and heat reduction. It has one of the longer acrylic warranties available at 15 years.
• Ames: $0.65-$0.75 per square foot. Makes commercial grade acrylic and liquid rubber products for waterproofing roofing and decking.

Contact a professional roofer for a quote on these less common brands.

• Uniflex: Available from Sherwin Williams.
• Hydro Stop: a masonry and concrete sealant. It's possible to use this on concrete tiles.
• Dr. Fixit: fully adhered elastomeric for concrete roofs (concrete tile).
• RoofSeal: creators of Ellemex an elastomeric coating for concrete tile and Reflect, a sprayed on acrylic coating for metal roofs.

Cost of Resealing a Flat Roof

A complete tear-off and replace of a flat roof can cost anywhere from $2,500 to more than $11,000. Resealing your current roof can extend its life and avoid replacement. How often you need to do this will vary depending on the type, brand, coating thickness and climate.

For example, a cheap acrylic may need work every 10 years. High-end silicones often come with 25 or even 50-year warranties. Though Polyurea has only been around for about 30 years, manufacturers often claim this type of sealant to be the longest wearing.

Fluctuations in temperature cause expansion and contraction, add to that humidity levels and UV rays all wearing on your roof. The best way to know how often you'll need to reseal is to talk to your roofing contractor. Ask them what type of roof to use for your climate and how often you'll need to reseal.

Reasons to Coat a Roof

Whether adding a coat when installing a new roof or just recoating an old one, there are several reasons it could be a good idea - cost, waterproofing, reflecting heat, extending roof life, or flame and chemical resistance.

Waterproofing

All types of the sealants listed in this article make the claim of waterproofing - even going so far as to claim a year-round ability to withstand ponding water. Silicone and Polyurea tend to withstand ponding better than other types of sealants. However, the best type will depend on your current roof and climate. Discuss options with your contractor.

Cool Roof Coating for Reflecting Heat

Coating a roof with white helps reflect solar radiation, reducing cooling costs by reducing indoor air temperature by as much as 20+ degrees. Acrylic, silicone, polyurea and EPDM all come in white. However, silicone tends to lose its reflective abilities faster than other types of roofing.

If you are sealing a pre-existing roofing membrane you may only need one coat. This can reduce costs an average of $0.50 to $1.50 per square foot.

Extend Roof Life

All the listed coatings claim to extend a roofs life. However, silicone and polyurea tend to do it better than any others, but you'll spend twice as much. Sealing a weathered roof, especially in harsh climates, can extend the life of your roof 10 to 20 years.

If you're on a tight budget, coating an existing weathered roof may cost $0.50 to $3 less per square foot than a complete tear-off and replace. Code allows no more than two layers of roofing at any given time. However, coating a roof is often allowed over these two layers. Additionally, some materials, like liquid EPDM and silicone, can end up costing more than just removing and replacing the current roofing system. To save money and extend roof life, use elastomeric acrylics. They tend to be a cheap - though short-term - solution for tight budgets.

Flame Resistance

Prices vary for fire resistant products depending on type and manufacturer. Flame resistance with a UL class A rating is often required by code for all roof assemblies. Have a roof inspector determine if you need a flame-resistant product and if so, which one they would recommend.

Resist Corrosion

This is a priority for homes with metal roofing near saltwater. However, you have options. Silicone, acrylic, liquid EPDM and polyurea are all highly corrosion resistant.

Cleaning and Repair Costs

Roof preparation for installing a coating includes cleaning. Primers and sealants won’t adhere properly to a roof with dirt or debris. Without proper adhesion, the roof will fail and require replacement.

Most sealants suggest power washing your roof prior to application. It will only cost about $200 and assures full adhesion. Also, sealants aren’t a substitute for mechanical repair. Repair holes, gaps and cracks first. Roof repair costs an average of $750. A licensed roofing contractor will include this in their bid. If you plan to tackle the preparation yourself, a roof inspection costs an average of $200.

Maintenance

Regular maintenance includes cleaning. Cleaning a roof costs an average of $400. Keeping it clear of dirt, leaves and branches is an easy DIY job. Good housekeeping to keep organic debris off the roof keeps mold, fungus, and moss from growing. Keeping it clean extends its life. Plus, it also helps the white finish reflect more heat.

DIY or Hire a Pro?

Since the roof protects your home or business from the elements, it's best to consult a licensed roofing professional. An experienced DIYer with the right tools may get this job done themselves to save about half the project cost.

However, improperly installing a roof leads to, at best, added expense fixing the improper installation. At worst, extensive water damage to the homes structure. If you do plan to tackle the job yourself, use the proper safety equipment and fully understand how to seal a roof before starting.