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Open Cell Foam Insulation for Homes and Businesses

Open cell spray foam is a flexible, lightweight insulation that expands to seal gaps and improve comfort, energy efficiency, and noise control. We use trusted products like BASF ENERTITE® to deliver reliable, long-lasting results for homes and commercial spaces.

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What is Open Cell Spray Foam?

Open cell spray foam is made of tiny cells that aren’t completely sealed, allowing air to fill the spaces. 
This structure gives it a soft, sponge-like feel and excellent flexibility. When applied, the foam expands quickly and creates an airtight seal which helps to prevent heat loss and draughts.

Unlike traditional insulation materials, open cell foam adapts to uneven surfaces and can insulate even the trickiest spaces like awkward roof pitches or tight wall cavities.

Where Can Open Cell Foam Be Used?

Open cell foam is ideal for many areas around a property, particularly where sound control and thermal insulation are important. Common applications include:

  • Loft and attic insulation
  • Pitched roof insulation
  • Internal walls and ceilings
  • Timber frame wall insulation
  • Cavity fill for sound reduction
  • Between floor joists

Because it’s breathable and flexible, open cell foam works especially well in timber-framed buildings or in areas where moisture management is important. While it’s not recommended for external use or in places prone to water exposure, it’s perfect for internal applications.

Key Benefits of Open Cell Foam Insulation

Spacious, unfinished interior with stone walls, a concrete floor, and ample natural light from windows, ready for renovation.
By sealing cracks and gaps, open cell foam helps reduce air leaks and heat loss. This means less reliance on heating systems during winter and air conditioning in summer, which helps lower your energy bills over time.
One of the biggest advantages of open cell foam is soundproofing. Its sponge-like structure helps absorb sound which makes it ideal for reducing noise between rooms or from outside traffic.
Open cell foam is light in weight and very adaptable. It easily fits around wiring, piping, and irregular shapes, which creates a continuous barrier that prevents heat from escaping.
Because it expands to fill even the smallest cracks, open cell foam creates a strong air barrier that keeps warm air in and cold air out. This helps improve indoor comfort throughout the year.
Many open cell foams, including ENERTITE®, are made with environmentally responsible materials. Using them helps reduce your carbon footprint while supporting sustainable building practices.
Open cell foam is generally more affordable than closed cell foam, while still offering excellent insulation performance. It’s a great choice for those looking to balance cost and comfort.
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Pitched Roof with Ventilated Cavity
Attic Floor
Pitched Roof with Counterbattens
Construction Instruction
ENERTITE® is suitable for use in the sloping rafters of a building where it is typically sprayed between the roof timbers to the required depths in a room in roof or attic space scenario. Continuity of insulation from rafter to wall should be maintained at eaves level. For both non-breathable (HR) and breathable (LR) roofing felts it is recommended that the Foam Master, builder and designer satisfy requirements of BS 5250: 2011, Control of Condensation in Buildings and current Building Regulations for ventilation in buildings. Rafter slides must be installed between the rafters to maintain sufficient air paths between the membrane and insulation. For habitable rooms, installation of a vapour control layer and lining boards should be used on the inside of the rafters. Enertite is NSAI and BBA Agrément approved for this application.
Construction Instruction
ENERTITE® is sprayed in between ceiling joists and onto the attic lining board. Additional counter joists may be required for construction of walk ways if ENERTITE® exceeds the depth of the joist.

Eaves ventilation must be maintained in line with Building Regulations and BS5250 :2011, Code of practice for Control of Condensation in Buildings.

Enertite is NSAI and BDA Agrément approved for this application.
Construction Instruction
ENERTITE® is suitable for use in the sloping rafters of a building where it is typically sprayed between the roof timbers to he required depths in a room in roof or attic space scenario. Continuity of insulation from rafter to wallplate should be maintained at eaves level. The roofing membrane must be vapour permeable (breathable) and counterbattens should be in place above the membrane in accordance with BS 5250: 2011, Control of Condensation in Buildings.

Open Cell vs. Closed Cell Foam:
What’s the Difference?

We often get asked about the difference between open and closed cell spray foam. Here’s a quick comparison:

Feature

Open Cell Foam

Closed Cell Foam

Cell Structure
Open, air-filled
Closed, rigid and dense
Texture
Soft and flexible
Firm and rigid
R-Value (per inch)
Lower (approx. 1.5-4.0)
Higher (approx. 6.0–7.0)
Air Seal
Yes
Yes
Moisture Barrier
No (not water-resistant)
Yes (moisture-resistant)
Acoustic Performance
Excellent
Moderate
Cost
Lower
Higher
Common Uses
Interior walls, roofs, lofts
Exterior walls, roofs, basements
If you're unsure which type of foam suits your needs best, we’ll guide you through the options and recommend the most suitable insulation for your property.
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Open Cell Foam Installation Process

We handle the full installation process to ensure the foam is applied safely and effectively. Here’s what you can expect when you work with us:

1

Free Consultation

We assess your property and identify the best areas for insulation. We’ll explain the benefits of open cell foam and answer any questions you have.

2

Preparation 

Our team prepares the space, protecting nearby surfaces and ensuring safe working conditions.

3

Foam Application

Using specialist spray equipment, we apply the foam to walls, roofs, or ceilings. It expands quickly to seal every gap.

4

Final Checks

Once the foam has set, we carry out a full inspection to confirm the job is complete and meets high performance standards.

WHY US

Why Choose Alpha Insulation for Open Cell Foam Insulation?

We’re trusted installers of spray foam insulation across homes and businesses. Here’s why customers choose us:
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Approved Installers 

We’re certified to install high-quality BASF ENERTITE® open cell foam.
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Expert Service

With years of experience, we provide honest guidance specific to your property.
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Eco-Friendly Focus

We offer sustainable products and responsible installation methods.
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Local and Reliable

Based in Ireland, we’ve built a strong reputation for reliable service and excellent workmanship.
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Grant Support Available

We’ll help you access any grant funding you may be eligible for.
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FAQs

Frequently Asked Questions – Open Cell Foam Insulation

Open cell spray foam has a lower R-value, so it requires thicker application to achieve the same insulation as closed cell foam. It is not a vapor barrier and can absorb moisture, making it less suitable for damp areas like basements or crawl spaces. Because it’s soft and flexible, it doesn't add structural strength to walls or roofs. Improper installation can lead to air leaks, and like all spray foams, it may release fumes during curing if not properly ventilated. Overall, while it’s effective in certain applications, it’s not ideal for areas with high moisture or where space and strength are critical.
Mortgage companies often dislike spray foam insulation, especially in roofs, because it can hide issues like timber rot or leaks, making surveys difficult. Poor installation can lead to moisture problems, and foam is hard to remove if repairs are needed. It may also reduce a property’s resale or remortgage value, causing lenders to see it as a risk—especially if there’s no clear evidence of professional, certified installation.
Some mortgage lenders raise concerns when foam insulation is sprayed directly onto roof timbers without proper ventilation or certification. This is more common with older installations or DIY jobs that weren't properly documented. When installed professionally with approved products like BASF ENERTITE®, and in line with building standards, there’s usually no issue. We, at Alpha Insulation Limited, carry out certified installs and provide all the documentation you need for peace of mind.
No, spray foam insulation is not suitable for all properties. While it offers excellent thermal performance and air sealing, it can cause problems in older buildings, particularly those with timber roofs, solid walls, or poor ventilation. In such cases, spray foam can trap moisture, leading to damp or timber decay. It may also make roof inspections difficult and affect mortgage or resale prospects. Suitability depends on the property’s construction, condition, and ventilation—so a professional assessment is essential before installation.

Get Better Insulation with Open Cell Foam from Alpha Insulation

Open cell foam insulation is a simple and cost-effective way to improve comfort, lower energy bills, and reduce noise. If you’re planning a home upgrade or looking to boost the efficiency of your commercial property, Alpha Insulation can help.
Request a Free Survey/Quote for Open Cell Foam Insulation
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