I recently had our Zonolite vermiculite asbestos professionally removed. The company used a large vacuum truck to remove it. They also ripped out the 6mm plastic vapour barrier in the attic. They explained that it was necessary to do so to remove the settled asbestos dust.

Currently, I have no insulation in my attic. I was going to go and put either fibreglass batts or blow in fibreglass insulation. However, I am concerned about not having a vapour barrier. The abatement company tells me that I don't need a vapour barrier in the ceiling/attic as the attic is well vented and as long as I install the insulation to at least R-40.

If we had to replace the vapour barrier, I am not even sure how I would do that. The trusses are 2x4 trusses, 24" apart. It seems that it would be a lot of work trying to re-install a vapour barrier underneath the trusses but above the drywall.

  • I cannot answer your question in terms of building code or industry best practice, but my attic does not have a vapor barrier and I live in northern Ohio. I have not noticed any issues. This is an unfinished attic with roll insulation between the joists and a ridge vent.
    – user4302
    Commented Oct 25, 2013 at 1:15
  • We live in Vancouver, BC and the house was built in 1974 if that helps
    – tegbains
    Commented Oct 25, 2013 at 5:01

1 Answer 1


Safest bet is to replace it of course - but in your case I wouldn't call it necessary.

There's an easier way to replace the vapor barrier. Run the barrier over the trusses. Keep it flush to the drywall but run it up over the truss and down again.

Of course, if your house is that old that it had vermiculite, I'm going to bet that you've got about 8 coats of paint minimum on your ceiling. Undamaged that will serve as a vapor barrier in its own right.

If you do batt insulation, however, then the way to install the insulation is paper side down, and staple the paper to the trusses down at the bottom. Not as good as wrapping the plastic over the trusses but its that or paperless. Do not put the paper facing the attic.

  • So just to double check, if I did run the vapour barrier over the trusses, would that affect the wooden trusses?
    – tegbains
    Commented Oct 25, 2013 at 19:13
  • Not if your barrier is properly sealed and is undamaged. The vapor barrier prevents the transfer of moisture, and it does this by stopping air flow. If the air can't move, the moisture in the air cannot migrate into spaces where it is likely to mold. Commented Oct 25, 2013 at 19:23

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