Open Cell Spray Foam Insulation

Klopp · 03-02-2026 10:25AM #1

I recently came across a company close to me that provides open-cell spray foam insulation for attics and similar areas. They’re registered with both the NSAI and SEAI. I got in touch to ask whether open-cell spray foam could be used in a timber-framed house, specifically in the gable walls on either side of the house.

I’m aware there’s a lot of debate around spray foam insulation, with both positive and negative opinions. What I’d really like to hear is whether anyone here has had it installed in their walls? The company has said it’s possible, but that’s as far as I’ve gone but it has perked my interest a little more.

horse7 · 03-02-2026 10:35AM

Will be interested in following this post.

Calahonda52 · 03-02-2026 05:27PM

More over here:

https://www.boards.ie/discussion/2058430798/spray-foam-insulation-vs-pir-attic-conversion

Klopp · 04-02-2026 09:55PM

I managed to speak to someone who is very knowledgeable, and they advised me this is not optional. There are options for spray foam open cell and more but ideally you first need to get a survey by an expert. I am happy to share details via PM if anyone is interested.

Calahonda52 · 05-02-2026 10:58AM

why do you mean by and they advised me this is not optional.

Did they mean its not an option with timber frame {TF]?

If so they are correct.

Are you talking about the TF gables in the attic

Klopp · 06-02-2026 12:53PM

https://www.boards.ie/discussion/comment/124207572#Comment_124207572

The first company i contacted said they could spray open cell foam from the attic downward, which I was very skeptical about and also the price had the alarm bells going off. The second company, who I emailed for advice, ended up ringing me and speaking to me for about 40 minutes. They confirmed that you can fill walls with open-cell foam using a slow-pour method, but not from the attic as the first company suggested. This person recommended that i get a survey done but first job would be having my attic sprayed with open cell with venation spacer. He mentioned that there’s a lot of misinformation out there, many people in the UK and the North typically use closed cell, which is much denser. This guy's company is registered with SEAI and they do a lot of work all over the country. I'm still in two minds but if i proceed, i will get a Survey done first and make sure this is all above board with certs.

He mentioned that, depending on the results of a survey, he would recommend applying open cell spray foam to the attic floor, followed by a layer of cellulose insulation.

Calahonda52 · 08-02-2026 10:11AM

Thanks, what exactly would the terms of reference be for the survey?

I value my PL insurance😀 so am interested in what you/they expect.

They don't know waht is used in UK/NI.

Yes closed cell is denser but its also more expensive

My concern with SF on ceiling is what it might do blocking up the air soffit air vents

Klopp · 09-02-2026 10:43AM

The survey is so they can recommend the right options based on your type of house, such as the build, whether it’s brick or timber, and whether it’s detached. The survey will help them identify cold spots and checks whether the walls are insulated or if there are any gaps.

Now when they spray the roof, they use ventilation spacer cards between the rafters, leaving a gap to ensure continued airflow. Any existing roof vents i would imagine will remain in place and are not blocked, as the spacer cards maintain proper ventilation?

Open Cell Spray Foam Insulation

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