Finish Basement Insulation Requirements

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Posted by: from Milton
4/26/2011 at 6:52:56 PM

I am finishing my basement in Milton, Ontario. Can anybody tell me the MIN requirements for insulation. I know the best practice guide states full height basement insulation is advised, but what is the bare min. required as per the most recent Ontario Building code.


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Date/Time4/26/2011 at 8:41:13 PM

Hi Jason.

When it comes to basement framing and insulation incorporating best building practices is very important in order to effectively manage moisture and prevent mould growth. Minimum requirement is to ensure wood is not in contact with cement ie base plate on a gasket and studs set off min 1" from the foundation wall. Min insulation is R12 and all you have to do is insulate to about 2 feet below grade. What you see in the basement of newly constructed homes is "rolled insulation" applied to the wall with strapping. Please note that the rim/floor joist space also has to be insulated, VB and sealed as well. However, that is not the way to properly insulate and seal a basement. Let us know if you would like a description of best practices as it pertains to framing and insulating the exterior walls of your basement.

I trust this specifically answers your question.


Kingsway Construction Inc.

Glenn Rosborough

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Jason in Milton
Date/Time4/27/2011 at 9:23:27 AM

So the best practice guide is just a suggestion and not an amendment to the building code?

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Date/Time4/27/2011 at 5:33:32 PM

The building code was amended to move towards full height insluation so that all permits after Dec 31 2008 included what is referred to as "near full height" basement insulation. It call for insulation to be installed from the underside fo the subfloor to the slab but allows for a gap at the bottom not to exceed approximately 15" from the slab in the case of damp/moisture problem basements. The walls have to be damped proof or some of us prefer to use Typar (reversed). The studding with R12, VB, sealed boxes etc is then applied.


Kingsway Construction Inc.

Glenn Rosborough

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Chris from C.C. Reno Inc. in Georgetown
Date/Time4/30/2011 at 9:37:51 AM

I fully agree with Glenn. If you are going to finish your basement and it currently has the insulation wrap from the builder,you should remove it and install a tyvek/typar/housewrap reversed prior to insulating which prevents moisture from getting in yet allows the wall cavity to breath. Some contractors like to use the waterproof foundation paint that is available now.The insulation the builder installed is to code for an unfinished basement. As soon as you frame and close the walls in,it changes everything. If not done correctly it will cause mold/mildew and rotting problems. Insulation(with the exception of spray or rigid) should not touch your bare foundation walls as it will act as a sponge and soak up all that moisture. Proper VB and taped correctly including between the floor joists is very essential too.

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Tom in Brantford
Date/Time11/28/2013 at 2:01:34 PM

I am finishing my basement and I have the builders insulation with plastic running down to about 1/2 way. I read the post about taking all that down, this tyvec do I apply it to my foundation wall?

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