SOLVED: Spray Foam Roof Insulation Problems And Pitfalls (2022)

SOLVED: Spray Foam Roof Insulation Problems And Pitfalls (1)

With energy prices increasing almost on a monthly basis, and the weather giving us all kinds of extremes, insulating our homes has never been more important.

This fact has been recognised by the UK government, who have been promoting insulation for many years in a bid to lower energy bills, and make our homes warmer and more comfortable to relax in.

But what if your choice of insulation actually causes more problems than it solves? Many people have concerns about thespray foam roof insulationproblems that it may cause. Is it really an issue or are the advantages outweighing the disadvantages?

The Energy Saving Trust estimates that the average UK home can save as much as £300 per year simply by adding insulation to the loft or roof. In most cases, the recommendations are based on mineral wool insulation to a depth of 270mm on the floor of the loft.

(Video) Spray Foam Insulation — The Ugly Truth?

When it comes to spray foam insulation that is applied to the underside of the roof between the rafters, the financial benefits are even more impressive, with the initial outlay recouped within just a few years on average.

It is clear, however, that the right application of insulation in your roof can be beneficial – but perhaps the operative word is the “right application”. It is easy to get it wrong, as the following article reveals…

What Is Spray Foam Insulation?

Spray foam is a liquid mixture of isocyanate and polyol resin that is forced together under pressure. When sprayed onto a surface it adheres and then expands to up to 60 times its original size. The result is a waterproof and airtight barrier to both water entering and loss of warm air from your home.

Spray foam can be used in many applications around the home, but is most commonly used as an insulation product either onthe rafters of your roofor inside your interior and exterior walls.

There are two main types of spray foam insulation:closed celland open cell. The former is a dense material that is perfect for sound insulation, while the latter has larger air pockets, and works well as an insulation material. However open cell does allow more air to pass through, enabling more effective ventilation.

SOLVED: Spray Foam Roof Insulation Problems And Pitfalls (2)

When using spray foam insulation, you can achieve an entirely waterproof and airtight solution, but this can mean that warm air can become trapped in the space.

(Video) Do not use SPRAY FOAM until you watch this! Our SPRAY FOAM ventilation and humidity nightmare!

When Roof Insulation Goes Bad

The main concern that people have when it comes to insulating the roof or loft room is condensation. This is actually more likely to happen if the insulation is applied to the floor of the loft (the most common location of mineral wool insulation).

The reason is that the insulative barrier is between the main rooms of the house andthe cold space of the loft. This means that there is a huge imbalance between the two spaces, causing the build up of moisture when the cold air meets the warm air.

In the case of spray foam insulation, it is applied to the roof rafters,balancing the temperaturein the loft with the rest of the house. This minimises the issue of cold air meeting warm air. However there are still some issues with spray foam insulation on the roof that can be avoided.

Poor Ventilation Equals Condensation

When using spray foam insulation, you can achieve an entirely waterproof and airtight solution, but this can mean that warm air can become trapped in the space.

For this reason it is important to haveventilation optionssuch as a window, Velux or just vents. You can also choose spray foam that is more breathable, such as the open celled variety, as this will allow the warm air to escape.

You can also prevent humidity in the rest of your home by taking advantage of window openings, trickle vents and air bricks.

Your home will certainly be warmer and more airtight, but this can mean that build up of warm air and steam from showers and cooking can find it hard to escape. It makes sense toair your home regularly.

(Video) Spray foam insulation nightmare: What can happen if it's not installed correctly (CBC Marketplace)

SOLVED: Spray Foam Roof Insulation Problems And Pitfalls (3)

Spray foam will usually last in excess of thirty years; therefore, any foam that starts to fail before this is likely to have resulting from an incorrect mix of materials

Incorrect Application: 3 Problems It Presents

Almost all of the problems associated with spray foam roof insulation comes down to incorrect application. In other words, the spray has not been used in the right way, or the mixture is not right for the location. This can cause a few problems, including the following:

● The area has not been covered adequately causing gaps or without the required depth. The recommendation is that around 100mm of spray foam is used between the rafters, and that it is spread evenly throughout the entire space. If there are gaps, water may penetrate through, and moisture can quickly build up, leading to mould and mildew. It can also mean that the insulation is not working as well as it could be,
● The mixture of materials is incorrect leading to the foam failing to adhere to the surface or crumbling after a short time. Spray foam will usually last in excess of thirty years; therefore, any foam that starts to fail before this is likely to have resulting from an incorrect mix of materials.
● Unstable or dangerous fumes. This is extremely unusual; however, it can happen if the mixture ratio is not correct. The foam will usually cure almost immediately once it is sprayed, and certainly within a few hours. If it fails to set, the fumes can be harmful. For this reason, it is essential that you choosea good contractorfor your project.

SOLVED: Spray Foam Roof Insulation Problems And Pitfalls (4)

There are somany reasons to choose spray foaminsulation including the speed of application, the high thermal values, the ability to get the same thermal value from less depth of material and the fact it lasts many years!

Rotting Of Roof Timbers: When Saturation Sets In

One main concern that is often brought up by home surveyors is the issue of water penetrating the roof and not being able to escape through the spray foam.

(Video) Spray foam insulation & mortgage concerns

This can happen when the roof becomes damaged on the outside, and water gets into the space between the spray foam and the underside of the slates. This can cause condensation due to the temperature difference between in this space compared to the rest ofthe loft room.

This condensation can saturate the wood trusses and rafters, leading to rotting wood.

The best way to combat this rare issue is to ensure your roof is always in good repair and to choose a spray foam product that is breathable. Ventilation in the roof will also help prevent this issue.

This issue of interstitial condensation has been researched by the Glasgow Caledonian University and it was found that while condensation can be present in an insulated roof, it doesn’t usually lead to wood damage.

This was mostly because the problem only occurs during colder months, as well as when it rains; however, it is not always present.

Unable To Repair The Roof: Why D.I.Y Attempts Are Best Avoided

Another concern is that if spray foam is applied to the underside of the roof slates, it can mean that it is impossible to remove individual slates, and subsequently repair or replace them.

This can be alleviated by spraying onto boards, or another barrier material. Most roofs are constructed with the tiles over a wooden board, so it is rare to apply spray foam to the underside of the tiles directly.

(Video) This problem with the spray foam insulation stumped us!

There are somany reasons to choose spray foaminsulation including the speed of application, the high thermal values, the ability to get the same thermal value from less depth of material and the fact it lasts many years.

With the right application, and attention to the issues faced by each home, you should have many years of worry free insulation in your roof space. Take the first step today to creating cosier conditions, by calling 0800 1700 636, or by simply clicking the button below!

FAQs

Is there a problem with spray foam insulation? ›

The poor application of spray foam insulation by an untrained or unlicensed contractor can lead to several problems, according to Fine Home Building. Poor application includes off-ratio spraying of the material, bad odors, and a lack of adhesion. A permanent odor can also be created when this happens.

What is the disadvantage of spray foam insulation? ›

On the downside, spray foam insulation comes at a price that is considerably more expensive than fiberglass. Often times, spray foam is triple the price of fiberglass and sometimes it can be more. Applying spray foam insulation is also something that is not advised to do by yourself unless it is a very small job.

What are the disadvantages of foam? ›

Closed Cell Foam PROSClosed Cell Foam CONS
Improved Coefficient of FrictionTend to have higher densities than open cell foams
Superb strength, and tear resistanceLower breathability than open cell foams
Varying degrees of hardness yet lighter than solids
Non-porous; less permeable to liquids & air
1 more row

Why do lenders not like spray foam insulation? ›

So why is it a problem for mortgage lenders? By sealing the roof space with this material, air circulation can be restricted to the roof and timbers. This can lead to condensation, which in turn can eventually lead to the rotting of the wooden roof supports.

Is spray foaming your roof worth it? ›

If you see the benefit of insulating your new construction home correctly from the start for long-term comfort, energy savings month after month, and fewer headaches while you live in the house, then spray foam insulation may very well be worth the extra cost to you.

Can spray foam rot your roof? ›

Studies show that open-cell spray foam is risky in colder climates. Indoor moisture diffuses through the foam and comes in contact with the cold roof sheathing. The spray foam traps the moisture against the roof, which results in eventual decay.

Can you spray foam the underside of your roof? ›

Open-cell spray polyurethane foam or closed-cell spray polyurethane foam (ccSPF) insulation can be sprayed along the underside of the roof sheathing to provide a conditioned and insulated attic space that can be durable and efficient in all climate zones (see Figure 1).

Does spray foam insulation ruin your roof? ›

What this study means is that you can insulate the roof deck of your home with foam insulation without any adverse effects to your shingles. Foam insulation creates thermal resistance, which is keeping that hot air out during the summer and your cool air inside.

Can mold grow on spray foam insulation? ›

As a product, spray foam insulation does not attract mold. And unlike wood or metal, spray foam does not rot, rust or deteriorate. This means that an area properly sprayed with foam insulation will never become a food source or a hospitable environment for a mold colony.

How long does spray foam insulation last? ›

Typical Insulation Lifespan

The International Association of Certified Home Inspectors states that spray foam insulation, wrap tape and housewrap insulation can last for more than 80 years. At the same time, cellulose, loose-fill, foamboard, loose fill and rock wool insulation can last up to 100 years.

Does spray foam devalue your house? ›

SPF should never be used in older buildings

In fact, according to Heritage House, they have seen entire roofs rotted and unrecoverable after SPF has been used. They state that by using SPF in your roof, '…you will devalue your home by the amount that a new roof will cost, and more. ' And we agree.

Should you spray foam your attic? ›

Insulating the attic rafters with spray foam creates a conditioned space where your attic is the same temperature as the rest of your home. This keeps the external weather and moisture outside of the attic space so you don't have to worry about any moisture problems or air infiltration.

Which is better spray foam or insulation? ›

When it comes to which is best in the spray foam insulation vs. fiberglass debate, spray foam wins, hands down. If you're a DIY-er, you may be used to installing fiberglass insulation. But if you're looking for something that will last a lifetime, let a professional install spray foam.

Can you spray foam over existing spray foam? ›

Can You Spray Foam Over Existing Insulation? | Foam University

Can you sell a house with foam insulation? ›

Mortgage lenders generally rely on the surveyor to identify the insulation present and either use that valuation to make a judgment call, some lenders and most Equity Release providers refuse to lend against properties with spray foam insulation as a blanket rule.

How do you remove spray foam insulation from a roof? ›

Lacquer thinner is an excellent solvent and highly efficient for removing spray foam roof insulation that has cured. This can be obtained from most paint shops or DIY stores. As with Acetone, it must not be used in confined spaces without considerable ventilation.

What are the pros and cons of spray foam insulation? ›

A Breakdown Of The Pros & Cons Of Spray Foam Insulation
Pros and Cons of Spray Foam Insulation
AdvantagesDisadvantages
Creates a highly energy efficient thermal envelopeUpfront costs are high and installation is expensive
Extraordinary thermal qualitiesPayback takes 2-4 years
Lower ongoing energy costsNot a DIY product
6 more rows
Aug 25, 2021

How long does a spray foam roof last? ›

Spray foam roofs are generally expected to last around 20 years at installation. The roof will last much longer than 20 years, but this is the standard warranty period. This all depends on the thickness of the foam and the coating, and applying more of either of them will generally extend the warranty term.

How thick should a foam roof be? ›

A: Dura-Foam roofs are a minimum of 1″ thick on most commercial and residential roofs. Standard thickness over occupied areas on residential roofs usually is a minimum of 1.5″. Thickness may be greater to meet insulation or drainage requirements.

Is 2 inches of closed cell foam enough? ›

Closed cell spray foam should be 4- to 5- inches on the ceiling and 2- to 3-inches in the walls. This might come as a surprise to you, but honestly, this is all the spray foam it takes to get the biggest bang for your buck with the air seal and thermal resistance needed for certain areas of the home.

Do you need rafter vents with spray foam insulation? ›

Do You Need Roof Vents With Spray Foam Insulation? - YouTube

Does a spray foam roof need to be vented? ›

By using an air-impermeable insulation, like spray foam, on the roof deck will stop any air movement. If the home's building envelope is completely air sealed, then the air traveling up to the attic won't be unbearably hot, and there will be no need to cycle it out with vents.

How much weight does spray foam roof add? ›

Spray foam that's used for a roofing system weighs about one pound per square foot.

Should you insulate the underside of your roof? ›

roof insulation is no-contest. The floor wins every time. Insulating the floor is standard practice for an unfinished attic space. The exception to this rule takes place when families opt to convert an unfinished attic space into something usable or livable.

Does spray foam insulation cause condensation? ›

Because foam insulation is seamless and airtight, condensation does not occur. Meaning that cold and warm air will never meet. There for impossible for them to reach a dew point and create condensation on your walls and roofs.

What is the best insulation to prevent mold? ›

Fiberglass insulation without backing may be the best choice. Cellulose insulation is constructed of ground paper, which is an ideal food source for the growth of mold if it becomes wet. Cellulose should only be used when it's absolutely certain it will not get wet.

How do you remove mold from foam insulation? ›

You can use bleach solutions to remove the mold. You can also try insulation over mold, with the foam making it impossible for the fungus to access oxygen.

Will termites eat through foam insulation? ›

Researchers have concluded that termites do not eat the foam board insulation but they will tunnel through it. Insulation also provides potential protection from predators and also retains moisture, two requirements of termites.

How do you seal a foam roof? ›

When repairing your foam roof, choose a foam kit, roof cement, flashing compound or elastic cement that is compatible with your foam roof coating and other roof system materials. Give patches and repairs sufficient time to cure and ensure new seals and seams are water-tight before you start recoating.

Does spray foam insulation shrink over time? ›

Spray foam in particular has been sold as a thermal insulator and air barrier in one. But once installed, spray foam, similar to foam boards, will expand and shrink over time. And both open and closed cell spray foam can and do regularly shrink and pull away from other air barrier components.

What is the best roof insulation? ›

Made from fiberglass, cellulose or recycled materials, loose-fill or blown-in insulation is a good option for filling a large space, such as an attic or crawl space.

Can you have too much insulation in your attic? ›

It's possible to over-insulate an attic as too much will cause moisture buildup and eventually result in mold. Eventually, adding more insulation leads to diminishing returns in trapping heat as well.

What is the best way to insulate a house roof? ›

How to Insulate your Roof | Fuel Poverty - YouTube

How thick should spray foam insulation be in attic? ›

“Normally, what we teach is that all foam applications should be installed in 3/4-inch to 3-inch-thick lifts. If foam is applied thick and quick — say, 4 inches thick — you gain yield. You can cover more wall with less foam. But the foam will be less dense.

What is best insulation for attic? ›

Spray foam offers the best attic insulation performance available. Choose from two types: closed-cell and open-cell, aka 2-pound and ½-pound, respectively. They sport insulation values of approximately R-6.5 and R-3.6 per inch, respectively.

Can you spray insulation over old insulation? ›

According to ENERGY STAR®, you can put new insulation over old insulation, “unless it is wet.

Is it better to remove old attic insulation before adding new? ›

Expert contractors that specialize in insulation advise that removing old fiberglass insulation is best before installing new cellulose insulation because of possible mildew, mold, or rodent excrement.

Can you put a foam roof over shingles? ›

Spray Foam Over Shingles?! Not As Crazy As You'd Think! [Whiteboard ...

Does spray foam devalue your house? ›

SPF should never be used in older buildings

In fact, according to Heritage House, they have seen entire roofs rotted and unrecoverable after SPF has been used. They state that by using SPF in your roof, '…you will devalue your home by the amount that a new roof will cost, and more. ' And we agree.

Will mortgage lenders accept spray foam insulation? ›

Mortgage lenders generally rely on the surveyor to identify the insulation present and either use that valuation to make a judgment call, some lenders and most Equity Release providers refuse to lend against properties with spray foam insulation as a blanket rule.

Does spray foam insulation cause mold? ›

Foam building insulation, in both spray foam and foam board products, is resistant to mold growth but as we will explain here it is not absolutely mold-roof, and on occasion we do find mold growth on the surface of even closed-cell foam, in open-celled foam (rare), and on th surface of EPS and other foam insulating ...

How long does spray foam insulation last? ›

Typical Insulation Lifespan

The International Association of Certified Home Inspectors states that spray foam insulation, wrap tape and housewrap insulation can last for more than 80 years. At the same time, cellulose, loose-fill, foamboard, loose fill and rock wool insulation can last up to 100 years.

Videos

1. How to Fix Condensation Issues With Spray Foam Insulation
(Kyle & Son Spray Foam Insulation)
2. How To Deal With A BAD Spray Foam Insulation Job | 6 Points to help
(Spray Jones)
3. Spray Foam Insulation Experience = Making Mistakes | What we learned..
(Spray Jones)
4. Top 5 Faker Mistakes With Spray Foam Insulation
(Spray Jones)
5. 3 Spray Foam Problems
(Matt Risinger)
6. Installing spray foam insulation to profiled metal roof cladding at storage facility in West Sussex
(Isotech Sprayfoam Ltd)

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