I just wonder if I can insulate my flat roof in northern India by following steps as under:

  1. Apply a cover of Bitumen
    1. Cover it with polythene (for water proofing)
  2. Lay used cement bags on polythene (LDPE bags will give thermal insulation.)
  3. Cover with soil.
  4. Lay tiles over it.

The traditional method used here is

I just wonder if I can insulate my roof by following steps as under:

  1. Apply a cover of Bitumen
  2. Cover with soil.
  3. Lay tiles over it.
  • I don't think this is a good method; but if you ask me you will have bigger problem with water proofing than with thermal insulation. Also I wanted to ask why you want to put soil on your roof. Is this your wish or do you think that it's a good solution? Mar 25, 2015 at 14:35
  • The practice here in North India is to put soil for thermal insulation. All the masons suggest it. Mar 26, 2015 at 3:19
  • I don't know why do they do it,but to tell you the truth I don't like the sound of that for many reasons: when you are covering the roof with soil you can damage water proofing layer, soil soaks and holds the water,you are putting extra weight on your floor,it is not simple to see if something is wrong with a roof (leakage) etc. I am not familiar with Indian building tradition but I would suggest that you use standard thermal insulation materials, and when it comes to cement bags I see no harm in using those, but not sure that it would help you. Mar 26, 2015 at 7:37

2 Answers 2


Certainly seems like it should be some improvement over the traditional method - how much is not clear, since the bags will presumably pack down and lose most of the insulating air spaces under soil pressure, but even "more or less solid" LDPE would be a slight thermal improvement over soil, if you have access to a lot of cement bags.

A rigid foam insulation (or foamcrete) would be more effective in this application, but presumably expensive or hard to source locally.


Instead of simply putting those bags there empty, you should fill them with an insulating material, like rice husks, lava rock, or any other lightweight, air-trapping material you can find. For that matter, you don't even really need to put them in bags.

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