HawthorneVillager.com

I did exactly the same thing in my previous house and we were happy with the results.

Now, I have a lookout lot and most of my back walls are well above grade. R-8 doesn't quite cut it, at least not for me. I agree that maybe it's partly a matter of personal opinion but there is no way I'm going to err on the cheap side when finishing my basement because the downside is too great. We're only talking about a few hundred bucks. In the grand scheme of finishing your basement, it's nothing.

#1: Builders often squish the R8 basement stuff when they install it, which drops the R value significantly

#2: R12 is definitely sufficient in basements, when properly installed with vapour barrier.

#3: if you choose to leave the builders stuff up, you'll lose a couple of inches of room space on each side, no big deal to some, but a big deal to others. So the easiest install with less going to the dump is to leave the builder stuff up, build the walls in front (you can squish it a little because of the next steps), cut slits in the existing vapour barrier as mentioned above), then put in pink R12, and 6mil plastic on top. (cost effective, less waste)
Dont forget to use vapour proof covers for your electrical boxes on that wall, and don't cheap out on the Tuck tape.

An incorrect install will really kill the benefits of the job - Ask pros for help (of which I am not! lol

It is not an expensive job when looking at the whole project - if your basement isn't warm and dry, you won't want to go down there as much!

I think you need at least R12 to meet code. So if you are looking to do things as per code the buidler insulation is insufficient.

Correct!
http://www.obc.mah.gov.on.ca/AssetFactory.aspx?did=844

"Ontario's 2006 Building Code requires that foundation walls separating
heated spaces from unheated spaces must have a minimum thermal
resistance rating of RSI 2.11 (R12), and RSI 3.34 (R19) for houses with
electric space heating in. Until December 31st 2008, the insulation must be installed to extend from the underside of the subfloor to not less than 600 mm (2 feet) below grade. After December 31st 2008, all basement insulation must be installed to extend from the underside of the subfloor down to the slab floor. A gap may be left at the base of the insulation, but no larger than 380mm (15 inches) above the slab floor."

nope what?
Doesn't the building code apply to finishing unfinished areas of existing buildings?

Does "basic renovation" have a definition in the OBC?
I love learning about this stuff, so send if you have.

What does "basic renovation" include and not include?

I'm definitely not saying you'd need to tear down the r8 before building.

According to the interwebs, "Concrete has an R-value of about 0.20 per inch of thickness"
... so... 1.6 to 2.0

That doesn't seem right to me. I think the code is effective as per the date of the renovation, not the date of the original construction. If one was to renovate a century home, that means they need to follow a code from the beginning of the century?

Our house was built in 2005, and we were required to follow the current code (I guess the 2006 code?). Also, for our electric inspection the inspector told us the a new code change required a GFI outlet in the laundry room, but since the change began effective after we had taken our permit out we were exempt.

I think you need to follow the code, as of the date of your permit. Of course if you are doing it without a permit then I guess you are really free to do whatever you want.