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Spray foam insulation

  • 07-01-2022 8:49pm
    Registered Users Posts: 176 ✭✭

    Hi was wondering if anybody can recommend a company that do spray foam insulation in Galway I want to do my attic I hear there’s a few bad ones out there so if anyone has any info would be great.


  • Moderators, Society & Culture Moderators Posts: 38,329 Mod ✭✭✭✭Gumbo

    Try get as much advice as possible from a local professional.

    Some Surveyors Professional Bodies have issued guidance to Surveyors advising that any domestic timber roof with Spray be classified as an area of concern and specific wording to be placed in reports to the effect that they require further professional investigation.

    The issue is pre purchase inspections you cannot see the condition of the structural timber members, felt/membrane or the underside of the roof finish. Therefore you cannot form an opinion to their current condition. You also cannot determine if there is dampness, water ingress or interstitual condensation present.

    Open Cell V Closed Cell is another issue with one being a sealant and the other used for thermal benefit.

    It has been noted that where Spray Foam is present, it can lead to premature erosion of the Structural Members and associated finishes. I've also heard of sales falling through because of it.


  • Registered Users Posts: 176 ✭✭Blues14

    Anyone can recommend a company and if anyone has had spray foam insulation done what do they think of it is it worth doing?

  • Registered Users Posts: 2,823 ✭✭✭MicktheMan

    I've tested many houses with the attic "sprayfoamed" and in all cases the sprayfoam is as useful as an ashtray on a motorbike when it comes to heat loss and you also have the increased risk of compromising the structural integrity of your roof as outlined above by Gumbo.

  • Registered Users Posts: 365 ✭✭Biker1

    Totally agree with Gumbo on this one. Unfortunately people believe the sales person when they say it's airtight and has good insulation properties.

  • Registered Users Posts: 45,796 ✭✭✭✭muffler

    I also agree with this. I'm not involved directly with this type of insulation but feedback I've had suggests it's useless.

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  • Registered Users Posts: 617 ✭✭✭tedimc

    I'm not sure about heat loss calcs, etc. but can speak from my own experience. We got an old house/new roof spray foamed back around 2014/2015 by a company in Roscommon.

    It made a huge difference for us. While probably not air-tight, you wouldn't feel a breeze in our attic spaces. I did use 25mm insulated slabs on the flat ceilings and 50mm on the vaulted ceilings to help, but I feel the main insulation is provided by the spray foam.

    Cardboard inserts were stabled between the rafters to ensure the 50mm gap underneath the roof membrane.

    The only downside for us was the mess from shaving the excess away when slabbing a vaulted section of ceiling. I'd also be wary of any ceiling downlighters - I presume most are LED now so heat is not an issue, but the old style ones would quite likely overheat.

    I used open cell foam on the roof. And closed cell in the cavity which is quite a bit more expensive. Depending on cost, I'd consider closed cell for the roof if I was doing it again. A lot more rigid.

  • Registered Users Posts: 757 ✭✭✭C. Eastwood


    The Building Regulations (BR) 2019 require Ventilation of the roof void of a domestic dwelling. 

    The minimum ventilation requirement are set out in Technical Guidance Document (TGD) F Ventilation. - here is the Diagram 11- Ventilation of Roof Voids, from this document- which shows the minimum requirements.

    If what you wish to do is not shown here, then do not construct it, as it will not be in Compliance with the Building Regulations.

    The Building Regulations have 5 purposes, 3 of which are as follows:- Health, Welfare and Safety of persons.

  • Registered Users Posts: 1,382 ✭✭✭dathi

    "If what you wish to do is not shown here, then do not construct it, as it will not be in Compliance with the Building Regulations."

    That is incorrect the TGDs show a prima facia way of complying with the building regulations, but does not preclude you from adopting a different approach to comply as shown in bold below

    taken from par F of building regulations TGDs

    Where works are carried out in accordance with the guidance in this Document, this will, prima facie, indicate compliance with Part F of the Second Schedule to the Building Regulations. However, the adoption of an approach other than that outlined in the guidance is not precluded provided that the relevant requirements of the Regulations are complied with Those involved in the design and construction of a building may be required by the relevant building control authority to provide such evidence as is necessary to establish that the requirements of the Building Regulations are being complied with.

  • Registered Users Posts: 21 mull

    Would you say this about using spray foam for an attic conversion as well? I'm looking to get my attic converted and assumed spray foam would be the way to go but from reading up on it online tonight I'm starting to have doubts.

    My house is currently A3 rated so I want the roof insulation in the attic conversion to be as good as possible. What would you recommend?

  • Registered Users Posts: 7,983 ✭✭✭youcancallmeal

    I've heard a lot of conflicting opinions recently as we are planning to get our attic converted. I've gotten quotes from several attic conversion specialists. Some swear by spray foam explaining that is has better thermal insulation properties than rigid board. They go on that they've done 100s of conversions with it and that will provide an architect's inspection and certificate of compliance.

    Other attic conversion specialist said they will use rigid board, when I asked why not spray foam they say it's more expensive/messy and rigid board works just as well. One guy did say he'll never work it because it'll rot the rafters over time.

    It's hard to know what to believe but I'm getting the impression spray foam if done right and following regulations is good but that there is a lot of people out there not doing it right/cutting corners. I think we're going to go with an attic conversion specialist who will use spray foam so I'm going to be questioning him on it and if I don't like what I hear I'll be asking that he use rigid board instead.

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  • Registered Users Posts: 2,823 ✭✭✭MicktheMan

    When you convert an attic space and bring it within the thermal envelope of the house, other than structural considerations, the basic thing you have to remember is that you are effectively making a giant hole in the top of your thermal envelope. There are 2 elements to the thermal envelope; insulation and air tightness. Yes sprayfoam or rigid board or fibre insulation all address the insulation element but none address the airtightness one. Therefore, all insulation methods need to have a separate, distinct & continuous air tight barrier installed.

    Anytime I air pressure test a house with spray foam in the absence of an air tight barrier the result is always disappointing for the home owner.

  • Registered Users Posts: 2,823 ✭✭✭MicktheMan

    Ask the prospective specialist for previous air tightness test results and how were they achieved. Bare in mind that, imo, the building regulation pass / fail criteria for air tightness is still pretty poor in comparison to best practice such as the passive house standard.

  • Registered Users Posts: 49 abbey

    Would multi foil insulation be an option instead of spray foam to help with air tightness in a draughty dormer ? Alongside insulation between the joists?