Spray foam insulation risks outlined by property body in new guide for homeowners

Brits planning to improve the energy efficiency of their homes are warned to do their research before using insulating foam.

The popular form of insulation has been widely used by homeowners for decades – but if not installed properly, it can cause problems when they come to sell or take out a new mortgage.

It is estimated that a total of 250,000 households have used spray foam insulation in recent years, and some are now facing serious consequences as a result.

Improper installation can pose a structural risk to homes and cause high repair costs. For example, the foam cannot provide proper ventilation, which can cause roof structures to rot.

Problems like these are picked up on building surveys and reported to potential buyers, potentially deterring them from buying the home.

Lenders may also be reluctant to provide new mortgages. In November, Britain’s largest building company, Nationwide, warned it could turn down mortgage applications on homes where spray foam insulation was poorly installed.

Now that the gas and electricity bill of the average household is rising to With £3,000 from next month many homeowners will be looking for ways to cut costs by making their homes more energy efficient – of which spray foam insulation is one option.

In response to growing concerns about cowboy firms and poor industry practices, the Royal Institution of Chartered Surveyors (Rics) today released a comprehensive guide to advise British people on the use of spray foam insulation.

The guide explains the effects spray foam can have on a home’s roof construction, thermal performance and value, as well as outlining the do’s and don’ts of installing insulation in a home.

Sam Piplica, senior building standards specialist at Rics, said: ‘We are pleased to present this free consumer guide to spray foam insulation to the public.

‘Rics’ job is to serve the public, therefore the main focus of the guide is to educate and raise public awareness of potential issues surrounding spray foam so that people can make informed decisions based on research and due diligence.

“Rics is also part of an industry working group on this topic to help not only our members, but the wider industry improve their products and services.”

What should homeowners know?

Spray foam, also known as SPF, is a form of insulation material that can be applied to roof spaces, walls and floors.

It is installed using a spray gun, which can come in handy when working with unusual designs and tight spaces.

While adding spray foam insulation can make a home warmer and reduce energy bills, it can also cause some unwanted side effects.

For example, sealing hot air inside can also trap moisture and make roof repairs more difficult.

Many of the UK’s older homes, although poorly insulated, are built to breathe. Poorly installed insulation can impede this ventilation and result in moisture.

Rics also advises homeowners to make sure they prioritize certain other home improvements before considering spray foam insulation.

For example, a building must be wind and watertight before money is spent on improving energy performance. Adding insulation to a poorly maintained roof can accelerate the decay of untreated wood roof structures, says Rics.

Risks of spray foam insulation

1) Hidden issues

Some spray foam insulation can make it difficult to identify problems with the roof because it restricts visibility from the roof space.

This is because if the wooden roof structure is covered with spray foam, it cannot be fully seen or inspected.

For example, if there is a roof leak behind some types of spray foam insulation, a homeowner may not notice it, which in turn can lead to rotting wood.

2) Moisture and condensation

Poorly installed insulation can lead to moisture and condensation, which can damage parts of a home.

For example, most pitched roofs on houses and bungalows are designed to be ventilated, and spray foam is a modification of the original design.

A drafty loft above insulation at ceiling level is generally a dry loft. Air circulation balances the moisture vapor to reduce condensation.

Spray foam, however, creates a warm roof void. It seals the openings to prevent drafts and retains heat – but will also keep moisture in unless precautions are taken.

The Rics advises all homeowners to seek professional advice on how to deal with any potential moisture hazards.

3) Energy saving

There’s a risk that installing spray foam insulation won’t have the desired energy-saving effect if it’s not done properly, says Rics.

While spray foam insulation is a better thermal insulator than the equivalent standard mineral wool attic insulation of the same thickness, existing attic mineral wool insulation can be supplemented if necessary.

This can result in a warmer home than if the typical maximum level of spray foam were installed between the rafters.

4) Fire safety

Homeowners should be aware of the fire risk to their properties when using polyurethane foam as insulation.

Polyurethane spray foam is typically a flammable material, which can withstand a small flame for only a few seconds.

While unused attic spaces do not require fire protection, having spray foam will increase the likelihood and extent of damage to the property and any adjacent homes if a fire breaks out.