I notice some powder substance on roof rafters in the attic. Its only at few places. Does anyone know what exactly it can be?

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It's just cellulose insulation dust from when it was blown in. It's identical to what's below.

Your recessed can should be covered better, by the way.

  • Any example of how it should be covered? – Sunit Apr 25 '18 at 21:27
  • Pile the insulation higher. There should be as much above the can as there is above the ceiling elsewhere. You could also overlay some fiberglass batts. – isherwood Apr 25 '18 at 21:34
  • Doesn't the can get heated up when lights are running. Isn't it better to keep the insulation away from the can. – Sunit Apr 25 '18 at 21:40
  • That's a good point. Make sure they're rated IC (insulation contact). If they're not, they're already a hazard. If they are, pile away. – isherwood Apr 25 '18 at 21:58
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    If it’s not rated, I’d build a box out of gypsum board Or wood that is a minimum of 2” away from the light on the sides and 6” away from the light on top. Then, cover the box with insulation. – Lee Sam May 6 at 23:03

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