Fireplace Replacement Queries

[pushkins]

I wouldn't recommend stryofoam for insulation anywhere near a heated source let alone a flue regardless of fireproof drywall, the problem really is that styrofoam doesn't have to burn to give off gasses, it can melt under heat and still give out the gasses and it doesn't take a whole lot of heat to melt it either.
You can check with your local building department for what they deem acceptable in your location (-27F and it's heading into spring....ewww ) in regards to acceptable insulation and clearances they require. A double layer of 5/8" drywall might be one solution.
A few insulation's are fireproof like "Rock wool".

There are flue insulation liners available, but again asking your local building department would be prudent.

[Wundrwut]

We are running new chimney pipes up the pre-existing chase (the outcropping building into the side of the house) the pipe will be exposed for the first 12feet, (the living space).. what you say makes sense, with the old insulation only going up the first little ways.. Is the styrofoam appropriate if there is fireproof drywall put on the walls(btwn stove pipe and insulation)? I assume that it is required where there is going to be insulation.. Should there be an alternative insulation chosen that would be safer?

[pushkins]

The insulation only needs to be where living space is adjacent to the space, no point running insulation in any other area other than that. You said your reinstalling a stand alone fireplace, are you using the same area for your new flue ?, if so you cannot use Styrofoam anywhere near the flue.

[Wundrwut]

Insulating and Air circulation

Taking the old out, we noticed that the insulation only went up about 8feet from the floor. (2X4 walls) We are considering putting in sheet insulation (white styrofoam)but are undecided about whether to run it up to the top of the house or to leave it uninsulated as we found it. There was a lot of frost build-up on the walls, and it would make sense to me to insulate fully.
I should note that we are in canada, and deal with temperature extremes (it is currently +1 celsius (33 F) and we are expecting a low tonight of -33 (-27 F)

not sure if it's relevant, but more information is better
again, thanks for your time
b

[pushkins]

by taking the pipe cap off, and pulling it up out the top of the house.b

That's pretty much it, the flue shouldn't be attached anywhere except the top of the old fireplace and the cap.

[Wundrwut]

My parents are taking out a pre-existing fireplace, taking out all the masonry work, and replacing it with a stand alone wood stove. The chimney pipe that is there already will be removed, and a new one installed. The bulk of the work has been done, and everything on the ground level has been brought up to code. All that remains is taking out the old pipe so that the chimney guys can come in and do what needs be done, without needing to deal with the old stuff.
I'm looking for guidance as to how to remove the old pipe. I've done roofing, and have removed chimneys by taking the pipe cap off, and pulling it up out the top of the house. If someone with experience can offer general guidance, things to look out for, and the like. I'm interested in doing the job right, making sure that no corners are cut.
Any suggestions will be helpful.
I appreciate your time.
b