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  • Underfloor Foil Insulation Removal

    Hi,

    I am wanting to remove the underfloor insulation on my property to put something better under there due to the current state of the foil and not actually working.

    I only realised last night there was law changes on the foil insulation about repair, install etc.
    Does anyone if I am legally allowed to remove it myself or do I need to get someone in to remove it?

    Or can I just put underfloor insulation over it?

    I am going by the below link
    https://www.building.govt.nz/about-b...bc-update-188/

    Cheers

  • #2
    Let us know what you find out.
    The ban is on repairing or retro fitting foil, but I haven't seen anything on whether its necessary to remove before fitting new insulation.
    On one website there was a recommendation to remove based on the assumption that it would fail to work if already damaged, but if it is not actually damaged and still in good condition, then fitting new insulation over the top may be just as effective.

    There is an electrocution risk in the removal process, same as the install process, so on the basis of safety it seems more sensible to leave in place.

    I also remember reading at some point that foil can collect condensation, which would not be good if it was then in contact with fibre insulation below it. However condensation would likely occur when there is only foil in place, the fitting of fibre insulation below it would tend to keep it warmer and thus prevent condensation I would guess.

    Its probably going to depend a little on where in the country you are and the condition of the ground below the floor.
    Food.Gems.ILS

    Comment


    • #3
      First thing I would ask is, are you talking about actual foil insulation? or the building paper foil between the floor joists and floor boards (which shouldnt be removed)..

      For actual foil insulation, i have only seen that it cant be installed moving forward, and you should be fine to remove it by yourself.
      The risk lies in the possibility of cuurent running through from wires creating electrocution hazzards.

      My advice if your DIY: turn mains power off before conducting any works (VERY IMPORTANT).. then ideally use a current tester to test the foil.
      IF your mains arent anywhere near the foil, then turning power off at the board should make safe for you to remove it.
      IF the foil has been touching wires anywhere, then inspect the wires as you remove it and note if there is any wear in the sheathing so it can be repairs or added to your risk register.
      Written by one of the team at http://www.chasepropertymanagement.co.nz/

      Comment


      • #4
        Originally posted by teamchase View Post
        First thing I would ask is, are you talking about actual foil insulation? or the building paper foil between the floor joists and floor boards (which shouldnt be removed)..

        For actual foil insulation, i have only seen that it cant be installed moving forward, and you should be fine to remove it by yourself.
        The risk lies in the possibility of cuurent running through from wires creating electrocution hazzards.

        My advice if your DIY: turn mains power off before conducting any works (VERY IMPORTANT).. then ideally use a current tester to test the foil.
        IF your mains arent anywhere near the foil, then turning power off at the board should make safe for you to remove it.
        IF the foil has been touching wires anywhere, then inspect the wires as you remove it and note if there is any wear in the sheathing so it can be repairs or added to your risk register.
        Its definitely foil and not builders paper.
        Since I should be able to do it myself with the power off I dont think there should be a problem.
        The property has just had a reno including new wiring so hoping it wasn't a cowboy sparky and be straight forward to remove the foil.

        Comment


        • #5
          You have to remove the foil before putting in any other insulation. It should be hanging/draping down between the joists, and if it has been damaged by cats, rats or tradeys then removing it and installing new insulation should be classed as maintenance.

          Comment


          • #6
            Originally posted by teamchase View Post
            First thing I would ask is, are you talking about actual foil insulation? or the building paper foil between the floor joists and floor boards (which shouldnt be removed)..
            .
            you raise an important point that for me is very much a matter of misconception / lack of knowledge.
            Foil insulation is obviously very different from foil backed builders paper

            Foil backed building paper

            foil insulation

            foil bonded to fibre insulation
            Food.Gems.ILS

            Comment


            • #7
              people were killed installing the foil and stapling through live wires. This livened up the foil and was deadly

              That web site suggests that existing foil could be live? Is that possible? but get a friendly electrical to check
              Leave the foil in place It adds to the thermal efficiency (but only a little). Place the new insulation under it between joists. It is exempt work under schedule 1

              Comment


              • #8
                Originally posted by John the builder View Post
                people were killed installing the foil and stapling through live wires. This livened up the foil and was deadly

                That web site suggests that existing foil could be live? Is that possible? but get a friendly electrical to check
                Leave the foil in place It adds to the thermal efficiency (but only a little). Place the new insulation under it between joists. It is exempt work under schedule 1
                The foil is draped so installing insulation over top of it will also cause it to scrunch up. Also when I worked for Right House selling insulation and heat pumps we were advised that the foil had to be removed as it reduced thermal efficiency. Very confusing.

                Comment


                • #9
                  Interesting -one says you have to remove and another says you don't.
                  MBIE doesn't say you can't - they say you can't add as new or repair.

                  Comment


                  • #10
                    foil acts to reflect radiant heat. Batts and the like create a still airspace. Foil works in combination with other materials to create an overall thermal insulation.

                    The draped foil formed a air gap where heat was reflected back into but not very efficient. Not worth doing but if it is there leave it do a job?

                    Comment


                    • #11
                      Oh well we followed my advice and removed the draping foil before installing Greenstuff.

                      Comment


                      • #12
                        Originally posted by Meehole View Post
                        Oh well we followed my advice and removed the draping foil before installing Greenstuff.
                        So is that really a 'it's a good idea to remove' rather than 'you have to'??

                        Comment


                        • #13
                          Originally posted by Wayne View Post
                          So is that really a 'it's a good idea to remove' rather than 'you have to'??
                          Like I said I was told when I worked at Right House selling insulation and heat pumps to advise the client that the foil had to be removed as it reduced the efficiency if having floor insulation installed over it.
                          Hubby is a builder and had an insulation business many years ago, he was the one doing the work on the property and that was what he thought was best practice as well.
                          However you do what you want Wayne. I'm only telling others of my experiences and what I know. Feel free to offer yours.

                          Comment


                          • #14
                            Originally posted by Meehole View Post
                            Like I said I was told when I worked at Right House selling insulation and heat pumps to advise the client that the foil had to be removed as it reduced the efficiency if having floor insulation installed over it.
                            Hubby is a builder and had an insulation business many years ago, he was the one doing the work on the property and that was what he thought was best practice as well.
                            However you do what you want Wayne. I'm only telling others of my experiences and what I know. Feel free to offer yours.
                            I was just trying to clarify if it was something that HAD to be done (a regulatory (or something) requirement) or just a recommended practise (recommended by someone).

                            I'm with JTB on the worth of the foil - it would add a little to, but subtract nothing from, the efficiency of the new insulation given that the new insulation is about trapping warm air and I can't see how a bit of foil could detract from that.

                            Comment


                            • #15
                              Originally posted by Wayne View Post
                              I was just trying to clarify if it was something that HAD to be done (a regulatory (or something) requirement) or just a recommended practise (recommended by someone).

                              I'm with JTB on the worth of the foil - it would add a little to, but subtract nothing from, the efficiency of the new insulation given that the new insulation is about trapping warm air and I can't see how a bit of foil could detract from that.
                              I'm no technical expert and cannot recall the reason for not having 2 types of insulation together, those being existing foil and batts/greenstuff together other than being told the foil reduces efficiency. I'm not sure where the trapped warm air would be as batts or similar are placed hard up under the bottom of the floor and then they are moulded over and stapled to the side of the joists. The foil draped and would most certainly bunch up if you put batts or similar on top of it.

                              Comment

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