Spray Foam Roofing (SPF) Pros and Cons

The best interior, the strongest exterior, expensive furniture and the same flat white roof? Of course, there are more roofing alternatives than you can imagine.

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I know, I know. It can be difficult to choose from the different types of flat roofing that are available, those that best suit your home.

Brief summary – The pros and cons of roof foam :

On: Very good insulation, energy efficient, easy to install and maintain, waterproof, versatile and relatively inexpensive.

Delays: They have to find a good contractor, they have to be inspected once or twice a year, repairs have to be done by an experienced contractor.

If you want the roof of your house to be strong, durable, insulated and waterproof, we know the solution!

This can be done with a polystyrene (SPF) roof covering. The question arises: What’s that? And what are the different pros and cons?

If you know this, you can make the right decision. So read on to see how it really helps you.

What is a sprayed foam roofing material?

Spray Roofing Foam or Spray Polyurethane Foam (SPF) is a construction method (walls or roofs) with sprayed polyurethane foam.

SPF is a type of plastic that moves from a liquid to a solid state in seconds and its volume is multiplied by 30 when it dries. It is one of the most economical and sustainable roofing, insulation and waterproofing systems available today.

Roofing systems based on SPF are manufactured by mixing and spraying a two-component fluid that forms the basis of the self-adhesive roofing system.

SPFs can be laid in different thicknesses, depending on customer requirements, to create a drainage slope or to achieve a certain thermal resistance (scientifically called the R value). The foam is then covered with a protective layer to protect it from the weather.

The first component of an SPF-based roofing system is a spray-painted, closed-cell polyurethane rigid foam insulation system. This foam consists of two components, isocyanate and polyol. The components are mixed on the spray gun with which they are applied to the substrate.

The second part, which is the protective surface, is usually a sprayed elastomer layer (although manual and motorised rollers can be used as alternatives).

The purpose of this coating is to provide weather protection, protect the foam from UV rays, protect against mechanical damage and support the fire-retardant function of the roof system.

Now that you know what a foam roof is, both in general and technically, you should read the following to get to know the different advantages and disadvantages of a roof system so that you can choose one!

Benefits of sprayed foam coatings

Easy installation:

The spray foam is easy to apply. It can be applied to all types of surfaces without disturbing the owner or the operation of a commercial property.

Installation of a sprayed foam roof

Easy maintenance:

It is not only easy to install, but also requires minimal maintenance once installed and can last for more than 50 years with proper care. Even if a new silicone coating is needed, it is not necessary to tear off the existing roof; a new coating can be applied over it to make it look like new again.

Energy saving:

It has excellent thermal insulation and acts as a barrier to heat, air and moisture. It keeps you warm in summer and warmer in winter, which helps to reduce the energy costs of a home or business premises.


You can customize the appearance of the roof. The texture can be supple, semi-rigid or even very dense.

Disadvantages of polystyrene insulation

Sprayed foam roof

Difficult to find a suitable contractor:

Finding the right contractor for roof works is difficult because not all contractors have the technical knowledge and insight to install roofs correctly.

Cannot be used in all weathers:

Polystyrene roofs can only be installed under certain weather conditions. This is not possible if there is snow or visible moisture on the existing roof. This does not mean that the insulation is not good in cold weather, etc. You should only apply it when the weather permits (for example, during the summer months).

Appropriate audits are required every six months:

You may often have to deal with this roof system.

The last word to remember is that foam roofs are rapidly becoming a roofing system suitable for commercial, industrial and other types of property. So if you’re the only one thinking about it, you’ve just got the answer to why it’s one of the best options in some cases.

How long does it take to spray moss on a roof?

The lifespan of your polystyrene roof is highly dependent on various factors, such as maintenance and climate, to name but a few.

There is no exact answer to this question, especially because the concept of the foam lining is relatively new. This kind of thing has only existed for about 50 years, so it can be very difficult to draw up a chronology of the external factors that influence it.

With this type of roof, however, some time can be expected, depending on external factors such as the elements, the climate, maintenance and even the traffic on the roof.

The original paint on a new roof should last 25 to 35 years. When you clean your polystyrene roof as part of the roof maintenance and repair process, you essentially have a brand-new roof; this extends the life of your roof by a further 20 to 35 years, bringing the total life of your roof to 70 years, which is a great time when it comes to roofing.

As said, a roof sprinkler system does not exist long enough to know how long it will take. However, since their introduction, many important improvements have been made to materials and methods, making them much more reliable.

Roof foam costs

Of course, the cost of your polystyrene roof depends on several factors. Factors to take into account include the slope and slope of the roof, as well as the size of the roof and where it comes from.

On average, the cost of spray foam roofs ranges from $6,000 to $7,500, with the above variations. The thickness of the SPF material also plays an important role in the costs.

You can expect to pay on average between $1.70 and $2.50 per square meter (for a typical SPF roof with a 1.5-inch foam layer, including material and labour costs).

However, prices vary depending on the contractor you hire to do the work.  These costs include the cost of materials and labour.

Of course, many other elements also play a role in determining the installation costs. The condition of your old roof plays an important role in labour costs, and the thickness of the foam you need will influence the cost of the materials.

In the long term, however, you can clean and re-apply the polystyrene roof, saving you a lot of money on the materials. In terms of labour costs, the process is fairly simple and manageable, so you don’t have to go bankrupt to do it.

Can you spray foam on the underside of the roof?

In short, the answer is absolutely right! Since you lose most of the insulation of your house through the attic, double insulating your roof is one of the best steps you can take to make your house as energy efficient as possible.

This level of sprayed foam on the underside of the roof is mainly carried out in unventilated attics as a form of extra insulation.

The process of foaming the underside of the roof in an unventilated attic has been going on since the mid-1990s, although it began in the 1970s.

For conditioned insulation in the attic, spray directly under the roofing membrane. It is an extremely durable and efficient method of thermal insulation that has proven itself in all climates.

This form of insulation offers a very effective thermal barrier compared to other insulation methods. As the polystyrene roof is airtight, there is no risk of leakage that could in any way compromise the insulation.

Do you need foam ventilation?

You need to understand that the purpose of foam roofs is to make the inside of your house airtight.

This means that any form of attic ventilation, particularly by means of a sprayed foam layer, is completely at odds with the purpose of the insulation. You want to keep your attic airtight to guarantee good insulation.

However, the argument for this measure is that the airtightness of the house allows bacteria or air pollutants to remain in the house.

You have no way out of your house. Some roofing companies consider it a liability if your house is not equipped with mechanical ventilation that allows clean air to enter. The quality of indoor air is generally poor.

However, there should be no ventilation in an insulated, airtight attic.

Can polystyrene be applied to a metal roof?

Spray foam has a 100% chemical adhesion to metal, so it can certainly be used on metal roofs. This is a great way to seal holes and leaks in your metal roof and make it waterproof again.

Just make sure that your roof is properly cleaned and dried, and that the foam is easy to apply to the surface!


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