Do I need CL2 cables?

It all depends on your states and counties electrical, fire, and building codes.

It's not just the law, it's a good idea!

The point of fire code wiring is that it doesn't spread a fire from one place to another too easily. If you care about your house being more resistant to burning down, getting CL2 cable is worth it. This is how I figure it:

Percentage = 100 * (House cost / Cable Price Difference)

If the percentage is less than 1, then getting the safer cable is a no-brainer.

The simple answer is yes. You may not need CL2 per se, (CMX, CM, CL3, CL2X, CL3X, etc.) may be fine as well (assuming a residential application).

While installing this cable through the wall will likely not need an inspection and nobody will ever come to your house and say you shouldn't do that - I would hate to give the insurance companies any excuse to not reimburse you should there be a fire in your home.

Carl