Advice on finishing basement

My wife and I recently bought a house with a considerably large basement. It's kind of an L shape and we were planning on converting one of the sides into three nearly identical rooms(there's a sump pump in the corner of one) and then doing something with the other space that's a little more restricted due to some support beams. What we wanted to know was, could we use the existing brick walls or would we need to frame over them? Also, we have a half bath down there we wanted to convert to a full bath. What kind of work is needed for that?

 

I am sure you have "block" and not "brick" for walls, but that's minor. For a proper effect I would frame the walls 1" from the block walls with 2x4's just like you were building a house. You can insulate the walls, keeping it from the block with your 1" gap, and allow air circulation behind the insulation. Don't be driving nails or tapcons in a perfectly non leaking block wall. Build the wall separately.
Bathroom enlargement is another story. It will entail breaking up concrete, cutting through rebars, if any and restructuring the plumbing drain and supply systems.

 

That's good to know. How do I space it? Just leave an inch off the side of the frame or should I fill in each side with drywall?

She wants to add a drop ceiling or something in there to cover the beams.

 

When you install your bottom pressure treated plate, space it about an inch or so from the wall. From there frame up like you would a house.....plumb and level. Install a top plate and your studs.
I missed what you said about sheetrock on both sides. Fill me in on that plan...you only sheetrock the living side.

 

The basement has been "finished" as one enormous area so we plan to reduce it down to a series of rooms.

 

OK, gotcha. Wherever you plan on putting a wall, if there is no support behind the sheetrock, you will need to cut a 3 1/2" wide area, top to bottom in order to insert a doubled stud. One will sit inside the opening and fasten to the original bottom and top plate, and the second one will sit proud and will provide a nailing surface for your intersecting sheetrock on the new wall. Lay out your bottom plates to the dimension you desire and figure your lumber. Any new outside wall will need to be built as an inside/outside corner using a number of pieces to form the corner to where you will have nailing surfaces for all your wall covering. We can get into that as you progress.