Is foam roofing worth the cost? Pros, cons, and verdict

Image source: J. Smucker Contracting

Jack Wisniewski

By Jack Wisniewski

November 18, 2020

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Considering spray foam roofing for your commercial building or home? Chances are you want to know what exactly the process entails, especially in terms of costs, as well as whether it is a worthwhile investment.

Before getting an idea of what you will likely pay for a foam roof and what benefits lie ahead, allow us to explain foam roofing in brief.

On this page:

What is foam roofing?

Foam roofing refers to spray polyurethane foam.

SPF is a popular choice for flat-roofed residential and commercial buildings due to its durability, ease of installation, and energy efficiency, among other advantages.

Spray foam comes in two types: open-cell and closed-cell. Open-cell foam is typically limited to internal foam insulation. In polyurethane foam roofing applications, closed-cell foam reigns supreme because of its greater density and better insulation against water and air penetration.

Foam roofing layers

These are the layers of a foam roof.

Installation involves combining isocyanate and polyol chemicals on-site and spraying the mixture over a roof deck or underlayment. Once on the roof surface, the liquid expands – reaching 20 to 30 times in size, or typically 1 to 1.5 inches – and forms a dense foam layer. To protect the foam from damaging UV radiation, fire, and other elements, installers apply one or more silicone or elastomeric roof coatings.

How much does it cost to foam a roof?

Including installation, SPF can cost anywhere from $3 to $4.50 per square foot. On a 2,400 square foot roof, you can expect to pay between $7,200 and $10,800 for a 1-inch thick layer of spray foam.

For those looking to minimize costs, you can opt to DIY with a spray foam kit. However, we recommend hiring a licensed professional to ensure correct and safe installation.

Other factors that can influence your costs include how thick of a topcoat you need on your roof. A thicker or multi-layer foam and topcoat will provide more insulation, which can help reduce HVAC consumption and foster energy savings.

Installation sites requiring more care, like around chimneys and skylights, can also increase overall costs if they take more time to spray properly.

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The benefits of foam roofing systems

Energy efficiency and insulation

Roofing installation and maintenance

A foam roof can deflect sunlight and keeps internal temperatures in and atmospheric temperatures out.

With an R-Value of 6.25 per inch, spray polyurethane foam boasts exceptional thermal resistance, meaning it keeps internal temperatures in and atmospheric temperatures out. This is why many homeowners and building owners also use SPF to insulate walls and attics.

With less hot or cold air escaping your structure, you can save on your electric bill by putting less stress on your air conditioning in the summer and heating in the winter.

When using a reflective coating, a foam roof system can also qualify as a cool roof.

According to the Office of Energy Efficiency and Renewable Energy, heating alone makes up about 42 percent of residential utility bills. An SPF roof can both reduce your energy costs and keep your building comfortable.

Waterproofing

SPF helps waterproof a structure in several ways.

First, a spray foam roof is seamless in that it is installed in one continuous layer. This means there are no nooks or crannies for water to seep in, unlike other flat roofing materials applied via overlapping sheets like TPO roofing and rubber roofing.

Second, most spray foam applications on roofs use closed-cell foam that resists water absorption particularly well.

Third, when installed correctly, spray foam roofs can also prevent standing water – a common issue with flat roofs that lead to leaks, sagging, and damage to the material, among other adverse effects.

Easy installation and maintenance

Roofing installation and maintenance

Image source: Kyko Roofing

As spray foam begins as a liquid, it seamlessly conforms to irregularities in a roof. This widens the value of spray foam beyond flat roofs and onto pitched and domed roofs, as well as over existing roof materials like shingles.

Spray foam also makes working around penetrations such as chimneys and skylights particularly straightforward. Within 30 seconds of contact with the surface, spray foam grows and effectively seals all cracks. Roofers call SPF roofing systems self-flashing because they eliminate the need to install flashing.

Should your foam roof ever show signs of damage, repairs can be as manageable and affordable as applying foam and recoating solely to the area that needs attention as opposed to replacing the entire roof.

Lifespan

After installation, a foam roof can last up to 20 years with regular maintenance, which is competitive with other flat roofing materials.

Even as the 20-year mark approaches or your roof’s warranty expires, a costly, outright roofing replacement may not be necessary. According to Phoenix Roofing Team, a foam roof can go beyond 25 years with a simple recoat five years after installation, which costs around 25 percent of the initial cost.

Each additional year for the life of your roof is another year you can delay the need to replace it, making SPF a particularly sustainable roofing material as well.

Overall, SPF can both save you money and the trouble of a roof replacement down the road.

Lightweight

At as little as a quarter of a pound per square foot, spray foam puts minimal demand on a structure. SPF can help roofs stay beneath minimum weight standards, which often pose a challenge for older structures and buildings that need to bear the weight of heavy snow.

If weight is a concern for your roof, foam is a practical choice.

The drawbacks of foam roofing systems

Needs the right conditions before installing

To adhere to a roofing substrate, the existing surface needs to be free of dirt, dust, oil, and any other contaminants, which can take time to clean off.

Additionally, effective installation requires a dry, warm window. SPF will not stick to a roof in the presence of moisture, ice, or frost. In low temperatures, the foam will not form correctly.

Should you urgently need a new roof during the cold or wet season, you may want to consider a roofing material that does not call for thorough cleaning and a stretch of pleasant weather.

Requires frequent care

Roofing maintenance

Image source: Western Colloid

For any roof, regular maintenance maximizes lifespan. SPF roofs, in particular, can take a beating from wind-borne debris, excessive foot traffic, and even birds.

If left to fester, ultraviolet radiation will progressively break down exposed foam and create pits for water to pool, which can lead to leaks, sagging, and rot.

You should have a professional inspect your roof twice a year to catch any issues and, if repairs are needed, have them addressed as soon as possible.

Potential health hazards

Although spray foam is considered relatively safe after it settles, it can emit toxic fumes during installation and curing – the process immediately after spraying when chemicals react to form the foam. These fumes can linger inside the building if not properly ventilated.

The American Chemistry Council advises skin, eye, and respiratory protection is necessary during installation to avoid exceeding exposure limits.

In turn, you may need to vacate your building entirely during the installation and curing phases to protect yourself and occupants.

After these initial stages, toxic emissions can pose issues for maintenance workers when spray foam is heated, which can happen during welding, soldering, or sanding work nearby. Additionally, renovations and demolition can spread harmful dust.

As long as you don’t disrupt your foam roof, toxic fumes should pose little risk. In the event you need hot work, renovations, or demolitions that involve your spray foam roof, maintenance workers should take care to avoid adverse health effects.

Overspray

Foam roof overspray

Image source: Spray Polyurethane Foam Alliance

As installation involves a spray application, droplets can stray away from the roof and onto the surrounding property.

Professional roofers should take the right precautions to reduce the chance of overspray and minimize its impact. For starters, a windscreen held up by one or more people can block the wind as well as catch rogue droplets.

Other ways to avoid SPF overspray is to move items inside or a safe distance away from the worksite, vacate the parking lot, and mask items that can’t be moved.

Although a few weeks of UV rays will eventually degrade small foam droplets, the possibility of overspray is something to consider, particularly if you can’t move exposed objects like landscaping and HVAC systems.

Correct installation requires skill

A roof can only work as well as it’s installation. With SPF, long-lasting protection requires precision during installation.

For instance, if the spray foam layer is not level, ponds of water can form in depressions, which can result in uneven weight distribution, water absorption, and eventual damage to your roof system.

A certified professional will not only know what precautions to take in terms of preventing health hazards and overspray but also how to deliver an enduring foam roof.

The verdict: a foam roof is worth it if you hire a professional for installation

Finished foam roof

Image source: Yoder's Roofing

Spray foam is an ideal low-pitched roofing solution. It’s energy-efficient, easy to install, lightweight, and long-lasting if maintained properly.

Like any roofing project, precise installation is key to ensure you take full advantage of the aforementioned benefits as well as avoid unnecessary headaches. A certified contractor will prepare your roof correctly as well as reduce overspray potential.

If you do end up deciding on a foam roof, have it inspected on a semi-annual basis to make sure your foam layer is intact and protecting your structure.

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