I did a lot of research when finishing our basement. I eventually went with a wall model recommended by building sciences corporation that, from outside in, is:
- existing exterior wall (concrete, concrete block, etc)
- foam board insulation (XPS or EPS, I went with EPS)
- stud wall
- sheet rock (I went with a paperless product called Densarmor
This is a system that Fine Homebuilding magazine also recommends and is considered valid by the US Department of Energy. I know this because our local building codes were still using the antiquated 'fiberglass + plastic' model and I had to do a ton of research to educate the local code enforcers before they'd approve this.
I went with metal studs for the following reasons:
- they're all perfectly straight
- I can carry 20 of them at a time (makes it REALLY easy to haul into a basement)
- easy to build in-place (no need to frame then tilt-up walls)
- cut with tin-snips in a matter of seconds
- mold can't grow on it
- can be installed without screws (can be crimped in place)
- at the time, were the same cost
- wiring channels are built-in
- you can use thinner studs (it's impossible to find straight 2x2's in wood around here)
There are a few cons, though:
- you can't easily nail into them for attaching baseboard
- you still need to frame out your doors with wood for the added strength
- you can't mount cabinets to the wall with metal studs
As for baseboard, I decided to use the new synthetic foam pre-finished trim. It looks pretty good, is super light, easy to work with and...it's not wood. So I thought it was another great product for a basement. Because it's so light, it was really easy to toe-nail it in to the sheetrock with an pneumatic trimmer.
As for mounting cabinets and such, on the walls where I knew I wanted to do this, I added 2x2's inside the metal studs for support.
The only corrosion issue that I'd be worried about is rust, and that should only be an issue if you still have a moisture issue in your basement. It'd also take a really long time for a stud to rust through and be any sort of problem.
Some tips:
- be sure to separate the floor plate from the concrete. I used 1/4 XPS for that and then power-actuated hammered them into the concrete. This thermal break will prevent moisture coming in through the concrete to condense on the metal
- don't screw them in. I did and while it's not that big of a deal, they make crimpers just for this purpose. Invest in the crimpers as it'll make things go really fast.
- be sure to buy plastic grommets for the electrical channels. You don't want your electrical cables rubbing up against the bare steel edges.
- wear really good gloves
As for your plan:
barrier (tar paper) on all exterior walls, Framing a stud wall, insulating, installing a vapour barrier, and dry-walling over top
...I STRONGLY recommend against that.
for starters, your plan involves two vapor barriers...that is a really bad idea. That will only trap moisture inside the walls. The modern recommendation (at least in colder climates) is to not use any vapor barrier in an old basement. Instead, use foam board for the insulation. Foam board is permeable, and the idea is that if water ever got on one side or the other, it could eventually dry to the other.
The other issue is that you want the insulation on the OUTSIDE of the stud wall. The foundation wall will be the coldest surface and is where moisture would condense. You want all of your framing on the inside of the conditioned space.
The proper way to put a water barrier in a basement is on the OUTSIDE of the foundation. Ideally, you'd have a water barrier and insulation on the outside of the concrete. But that's obviously really hard to retrofit.
I used to use a 7 1/4" metal cutting wheel on a circular saw. Works good, but wheel wears down fairly fast. There are also some good shear attachments that mount on drills. I'd advise you to make the cuts on the end going to the top, not the exposed bottom. Definitely have some spray paint or primer to treat the cut end, because it will rust. If you put the cut ends at the top under your ridge cap, you will be fine. The other alternative is to buy your panels cut to length before they land on the job. Several manufactures cut to order such as Everlast Metal Roofing.
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I'd personally be surprised if they were steel, but a magnet should be handy for verifying that they are not (or are.)
If you are in full destructo-mindset and not going to change your mind over the winter, drilling hole(s) and looking at what comes out of the drilled hole (and what you see looking in the drilled hole) can also be very diagnostic.
If, as seems far more likely to me, the pool is gunite or fiberglass, all you need to do is break up the top rim deep enough that it won't affect future uses (lawn, garden, etc) of that area, and fill it in - unless you are expanding the house into the area.
8 foot deep holes/trenches are distinctly hazardous to be in - if the dirt collapses, it can kill you. Either use digging equipment that keeps you out of the hole, or dig it very wide/sloped.
If it's actually steel, you'll want a 9" angle grinder to make short work of cutting it up, or a 4" if you find a 9" too much to handle. The 9" is faster but requires more effort to control. Investigate tool rental, and get double eye protection (facemask and goggles) and a cheap set of welding leathers so you don't set your clothes on fire. Grinder sparks hurt, and set fires if there's any fuel for them to hide in.