Should I insulate my basement ceiling?

Nina Hartt Published: March 21, 2019, 8:23 a.m.Last updated: April 4, 2019, 5:01 p.m.

My bungalow is around Toronto, and is a little over 100 years old with block walls in the basement. we recently learned our basement wasnt insulated properly, and probably done to hide some flaws. In response we’ve decided to rip it all out and do any necessary repairs. This is going to take us some time, and we probably won’t be done in time for next winter. We want to take the opportunity to open up the basement ceiling to inspect wiring etc. My concern is this; the unfinished basement will be cold next winter and that will spread to the rest of the house with the ceiling opened up down there. Should I insulate the basement ceiling? It’s possible that our basement is not suitable for refinishing, so it might always be cold.

Ive read about insulating rim joists and that seems to be a good idea that won’t contribute to moisture problems. It’s not a wet basement, but the block does get a bit of the white stuff gathering under the paint on the blocks. 


Thanks in advance 

Responses (1)

Ecohome April 3, 2019, 9:52 a.m. Reply

If your intention to insulate the ceiling is simply for energy efficiency and to provide comfort for the one winter that you’d be without basement insulation, I wouldn’t do it. I think you would come out far ahead by adding a bit of extra heat to the house and basement for that one winter than if you were to invest your money and effort into insulating it. Many basements in older homes simply are not insulated at all, and therefore they do have higher heating bills to show for it (which is not great long term), but for one winter I wouldn’t think twice about leaving it uninsulated.

The basement may not be suitable for refinishing, but it will for sure be suitable for insulating, one way or another. My  concern in your case, would be that it is a block foundation since they are not nearly as strong as a poured concrete foundation. It is only held together by the mortar, so it is more susceptible to cracking due to the freeze/thaw cycle between seasons. For that reason, block foundations are best insulated from the outside so they stay warm.

So, my suggestion would be to have it inspected by a qualified professional before deciding on a final method of insulating. The reason I suggest that, is that if your walls have not been well-insulated or insulated at all, they have stayed warm in previous winters. Were you to suddenly install insulation on the interior, they will no longer have as much heat moving through them to prevent them from freezing in winter. If the walls are straight, have no cracking or signs of  then you may be fine, but it’s just a point worth considering before you move ahead.