Open Cell Spray Foam Insulation

At Websters Insulation, we have over 40 years of experience in insulation. Our highly skilled team of engineers have expertise in both closed cell spray foam insulation and open cell spray foam insulation.

In recent times, we have seen an increase in the utilisation of open cell insulation, due in part to it’s efficiency of application and cost effectiveness. Open cell spray foam is particularly popular in the insulation of house roofs.

What is open cell foam insulation?

Open cell spray foam, as the name suggests, is constructed of cells which are left open, and filled with air. This is in contrast to closed cell spray foam, in which the cells are completely closed.

One of the properties of open cell insulation is that it allows water vapour to pass through, unlike closed cell insulation. Whilst this doesn’t provide the same waterproofing properties, it can help to prevent mositure build up that can lead to mould and rot. When installed properly, in conjunction with a vapour barrier, open cell spray foam can be a highly efficient insulation solution.

An added benefit to open cell foam is that it provides a much more effective sound barrier when compared to closed cell foam. This is one of the properties that makes it so suitable to residential properties.

Open cell spray foam also offers much greater expansion than closed cell once applied. This makes hard to reach areas much more efficient to insulate, such as those found within a house roof. The greater expansion also means that only one coat is usually required, as opposed to multiple coats of closed cell insulation.

Additionally, open cell spray foam uses significantly fewer resources in its manufacturing. This results in a more environmentally friendly product that is significantly more cost effective.

Is open cell foam insulation worth it?

Open cell spray foam provides an effective air and sound barrier that offers efficient coverage and appliction. This makes it an excellent solution for thermal and acoustic insulation, particularly within house roofs.

Closed cell spray foam typically provides more strength and rigidity and a higher level of thermal insulation, as well as acting as an effective vapour barrier. This makes closed cell insulation particularly suited to commercial and agricultural applications that require higher levels of performance.

However, for residential applications, open cell spray foam offers superior acoustic insulation, a lower environmental impact, and a greater cost-effectiveness.

Isothane WBF

At Websters Insulation, we use a high performance open cell spray foam insulation called Isothane WBF. It is suitable for a wide range of applications and can be used to reduce air leakage, in addition to providing effective sound deadening between floors.

ISOTHANE WBF is a water blown, two component 1:1 ratio, soft foam system which when processed through suitable spray machinery will produce a rigid foam of approximate density 10 kg/m3. Service Temp range -15°C to 70°C. The system has Agrément Certification for pitched roof insulation.

We use a Graco A25 Machine to apply the open cell product, which can be used to upgrade the thermal performance of roofs, floors or walls of any property, to meet current Building Regulations. It is commonly used for:



Existing House Roof


New Build House Roof


Loft Conversion


Timber Framed Walls


Roof Stabilisation


Existing Ceiling Voids (Dorma Type / Vaulted Ceilings)


Why Choose Websters Insulation for Open Cell Spray Foam?

With our wealth of experience in both open cell and closed cell spray foam, we understand the specific properties of each type of insulation. We undertake every project on an individual basis, utilising open cell spray foam only in suitable applications.

At Websters Insulation, our highly experienced and skilled team of engineers can utilise Isothane WBF open cell spray foam to produce effective thermal and acoustic insulation in a range of properties. By following proper installation procedures, open cell spray foam can provide an excellent insulation solution whilst offering unrivalled efficiency of application, environmental friendliness, and cost effectiveness.

Please don’t hesitate to contact us today for more information on open cell spray foam insulation or for a free quote. Alternatively, you can fill in our quote form below and we’ll get in touch as soon as possible.

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