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Minimum build-up on existing slab?

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  • 09-11-2015 11:18am
    #1
    watou
    Registered Users Posts: 20 ✭


    Hello,
    I've purchased a 60 sq. mt. cottage that was renovated about 10 years ago, and part of that renovation was to rip out rotting raised timber floors and dump in an incredible quantity of concrete, like maybe a foot deep, with a very thin layer of lino and laminate over that. The problem is that they also put in storage heaters, but I want underfloor heating driven by an air-to-water heat pump.

    Now I'm wondering if it makes more sense to just build up from that existing mass of concrete, using the thinnest advisable layer of insulation, floor heating pipes and screed, so I raise the floor maybe two inches maximum. The ceilings are high so the loss of headroom inside isn't an issue; the windows will of course be two inches closer to the floor and the doors will lose two inches of clearance, but the cost and effort of this approach is obviously so much less.

    My question is: is this a terrible idea? Is it possible to start with the very sound concrete they poured in 10 years ago as a subfloor but only build up further two inches, so that a low-temperature underfloor system will work properly?

    Many thanks for your thoughts on this. I really want to do it right, but I also want to be able to live in my new home at some point in my remaining lifetime.

    Thanks, John
    Tagged:


Comments

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    #2
    893bet
    Registered Users Posts: 8,768 ✭✭✭893bet


    I don't think it will work. You are talking about putting in an inch of insulation, plus pipes and screed. Waste of time IMO. You prob need 4-6 inches of insulation underneath.


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    #3
    watou
    Registered Users Posts: 20 ✭watou


    Thank you for that. Obviously not what I want to hear, but valuable to not fool myself. Would there be any arguments to support the "two more inches" approach, like "heat will rise anyway above a very thick slab," or is this just more wishful thinking?


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    #4
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,140 Mod ✭✭✭✭BryanF


    watou wrote: »
    Thank you for that. Obviously not what I want to hear, but valuable to not fool myself. Would there be any arguments to support the "two more inches" approach, like "heat will rise anyway above a very thick slab," or is this just more wishful thinking?

    Forget underfloor


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