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ICF vs Concrete Block

  • 16-12-2021 9:33am
    Registered Users Posts: 1,394 ✭✭✭ MacDanger


    Just starting a new build in the West and I'm wondering what people think on here about the pros/cons of ICF vs traditional concrete block? From reading online and talking to a couple of people, it's

    • CB is cheaper but blocklayers are in short supply at the the moment so that gap is narrowing
    • ICF is quicker than CB (esp with a shortage of blocklayers)
    • Every builder knows how to build CB, not all will with ICF so this may reduce the number of contractors bidding on a job

    Anything else that we should consider? Which would you go for?

    As an aside, with ICF, are there potential issues with bolting heavy things to the wall since the concrete is ~10-15cm from the painted surface? Say for example, you're doing a built-in shelving unit that might be holding something heavy, where is it anchored? Just into the plasterboard? Or does it go all the way into the concrete? Or is this a non-issue?



  • Registered Users Posts: 7,848 ✭✭✭ tom1ie

    Don’t know about the fist points, but regarding bolting something to the wall, is that not the same thing as fixing something to an insulated plasterboard wall?

    If so, the shelf or tv etc must be fixed to the solid wall behind the plasterboard.

    Problem is you have to go easy enough with tightening up the fixings so you don’t “crush” the insulation, at the same time as making sure you have enough of the fixing anchored into the solid wall.

    Get long fixings.

  • Moderators, Home & Garden Moderators Posts: 10,109 Mod ✭✭✭✭ BryanF

    you’ve started building and your wonderings this? Is the foundation poured?

    I used ICF foundation system, great job, reduced: digging out, concrete, steel quantities.

    Have you someone to detail the ICF? The only job I saw with ICF walls, was let down by the lack of arch drawings resolving any of the details.

  • Registered Users Posts: 1,394 ✭✭✭ MacDanger

    "starting" not "started"!!! Only just got planning so well away from actually starting. Haven't started to detail the ICF yet - I presume that's the engineer?

  • Registered Users Posts: 273 ✭✭ Biker1

  • Registered Users Posts: 1,534 ✭✭✭ Dudda

    Different thing. The architecture or engineer need to take those standard details and incorporate them into the design of the house. This new set of detailed drawings is what the builder will use to price and build the house.

    It raises a good point though that as contractors aren't as familar with the ICF you might need a more comprehensive set of detailed drawings. I'd be all for a more detailed set anyway as that reduces issues and claims for extras later onsite.

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  • Registered Users Posts: 325 ✭✭ fatty pang

    A lot of the ICF systems are not using the details displayed on their Agrement certificates when it comes to window/door apertures...which is no bad thing as many of their details aren't exactly robust. Door threshold details are almost non-existent (surprise, surprise).

    Definitely invest in a competent architectural technician to detail the window interfaces (most window suppliers will generally be as clueless as the ICF supplier) and ask him/her to pay particular attention to the window/door fixings. Nearly all the ICF systems I have seen on the Irish market are closing the cavity with EPS despite their 'certified' details usually showing timber bucks. As the OP has noticed, the load bearing concrete core will then be some distance away from the window/door frame and strap fixings are going to be 'difficult' for an attentive Engineer to stand over.