We are renovating a 1961 rural house in France. The ground floor is garage/basement, but both the first and second floors (in European terms) are a 30cm hard concrete subfloor with 10cm (4 inches) of underlayment on top of that. On the first floor it is a kind of soft, chalky, plaster-like substance, and on the second floor it appears to be a very soft concrete on top of sheets of something like drywall. We would like to remove the 10cm of underlayment on both floors to make room for underfloor heating and insulation. We are starting with the top floor in the next few months, and we are trying to figure out whether or not we can do it ourselves. The best quote we have received is for 15,000 euros for the demolition and removal of material for about 70 square meters x 7cm or about 10 cubic meters of material.

Here is an image of the second floor underlayment which is the one we are discussing:

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This is a lot of money out of our renovation budget, and though it seems like a lot of work, we are considering the possibility of doing it ourselves. I would like any feedback on how best to do it, and if we are crazy to take in on with just myself, my wife, and a friend who are all pretty handy with DIY stuff (doing flooring, drywall, etc) but definitely not professional in any way.

Our rough plan is as follows:

  • Hire someone to bring a dumpster to our driveway and provide a chute to dump material from which we will attach to a big window upstairs that can dump directly down into the dumpster. I am assuming that I can hire the window chute thing, but I don't know anything about that.
  • Build a small ramp that will take a wheelbarrow up to the exact height to dump easily on the window into the chute.
  • Rent one or two 60 lb jackhammers and get to work!

My rough time estimate in my head is that two people would be able to do about 1 square meter per 20mins or half hour, adding up to about one full 40 hour work week for two people. I think that's on the conservative side, but would welcome any feedback on that.

Specific questions I would like answers to:

  1. It seems like that with the very soft underlayment on top of the very hard concrete subfloor, it will be pretty easy to remove just the underlayment and not damage the subfloor. Should I be more worried about screwing this up and destroying the subfloor?
  2. I know there is some conduit in the underlayment, but we are planning to redo ALL the wiring and plumbing up there so I'm not too worried about it. Should I be more worried? Is there anything else I should be worried about?
  3. Is my rough estimate of one full 40 hour work week for three people working two at a time sound about right, given that we are not experts at this?
  4. Are we crazy to be doing this ourselves? :D

The only relevant experience I have with this is helping my dad tear up a concrete driveway of a similar size nearly 30 years ago. That was a lot of hard work, both just working the jackhammer and also hauling all the stuff out, so I would very much welcome the collective knowledge of this community.

  • For dumping into the chute through a window, working with 20 liter (5 gallon) buckets, not even full, might be a lot more practical than trying to dump a whole wheelbarrow from an elevated ramp... more loads, but a lot less precarious. Or, the tool rental may have a small conveyer belt arrangement (mine would not, but evidently they are common in Britain, no idea about France.) If the underlayment is "very soft" jackhammers may not be required.
    – Ecnerwal
    Jun 22, 2023 at 11:49
  • Think about it: you have 10 cubic meters of plaster-like material. If it's plaster-like density, you're talking about demolishing 22,000 kilos of material. You're talking about picking up, moving, and dumping 22,000 kilos of material. 22 tonnes. Are you up for that?
    – Huesmann
    Jun 22, 2023 at 13:03
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    On the second floor I'd strongly consider just cutting channels for the underfloor heating and whatever plumbing or conduits you need to replace or place, leaving the bulk of the material in place. The benefit of insulation between inhabited floors is minimal unless you don't heat the first floor.
    – Ecnerwal
    Jun 22, 2023 at 14:44
  • I presume the "very soft underlayment" is the portion just below the dark brown that looks like poured concrete. What is the broken egg-tray/pottery dish looking thing at the bottom of the hole? Some sort of drawing on your picture would help clarify what's what, or, since you're telling us about depths of layers, put a ruler/tape measure in there to give us a point of reference.
    – FreeMan
    Jun 22, 2023 at 17:32


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