My basement is not occupied and I would like to put Roxul insulation against the windows so it adds a bit more insulation in the winter. The material I plan to use is Roxul, my question is would it be safe to have exposed Roxul insulation around the house?

  • It is... however for another 50$ and less than half the time of the Roxul install, you can further increase insulation factor by reducing air movement by adding a vapor barrier.
    – Chris
    Jun 30, 2016 at 13:29
  • Thanks, but are you talking about adding vapor barriers around the windows where I am putting Roxul against? Or are you just advising in general wall insulation application, a vapor barrier should be considered?
    – KubiK888
    Jun 30, 2016 at 13:31
  • Could you edit your question to be explicit on the application? In general, the answer is 'Yes' . But it's with caveats.
    – Chris
    Jun 30, 2016 at 13:35
  • Depends on your basement. If any part of it includes walls above the foundation, you'll need to insulate those as well. (I'm assuming you have a concrete-wall foundation). Further, since the basement will always be cold, your best bet is to insulate the basement ceiling to avoid heat loss from the house itself. Jun 30, 2016 at 13:55

2 Answers 2


Roxul is our #1 choice of insulation in exposed areas.

  1. It is non-flammable.
  2. After installation it releases very little dust comparatively.
  3. The dust released has really no harmful effects other than slight irritation.
  4. It molds and conforms stronger than fiberglass and other roll insulation. Just make your cuts bigger than the area and compact the material in.
  5. It has little to no smell.
  6. Mice/Rats don't like it.

I personally have exposed ROXUL in my laundry room which is the only unfinished room in my house. It is jammed into ever joist crevice on outside walls. It also is in at least 30-40 basements I have finished. It is the best performing insulation I have used - my laundry room is an oven in the winter and was cool with fiberglass sheets. I would also suggest that you do not put up a vapor barrier unless the ROXUL is below human height - and really unless you are in a very cold climate you should not be insulating that low on a basement. For basement windows it is the perfect choice.

(Not affiliated with the company at all nor a fanboy. There are just a few products out there that beat the competition by a lot and I recognize that. Mike Holme's uses it on everything too.)


Roxul is safer than pink or fiberglass insulation, and a few pieces against your windows will be quite safe (but not beautiful).

However, if your basement walls are not insulated, I doubt putting Roxul in the windows will make any perceivable difference to your basement temp in general.

If your basement is insulated, you will likely have noticed that cold air "pours" off the basement windows in cold weather. If you would still like to have light and a view from the windows, another way to deal with windows, which I've found pretty effective, is to add a heat shrink poly film over the windows. Check out this one http://solutions.3m.com/wps/portal/3M/en_US/NAHomeEnergy/Home/ or google "heat shrink window insulation"

  • Putting ROXUL over windows correctly when it is cold outside will have a dramatic effect. Way more than poly. How effective will it be in a basement... well that probably depends on how well other things are insulated. If the insulation just is over windows maybe very little effect, but if the windows are the only thing not insulated it could be large.
    – DMoore
    Jun 30, 2016 at 19:19

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