You can then strap furring strips over the insulation (attached through the insulation into the masonry) and hang drywall or resilient channel and then drywall from the furring.Polyisocyanurate foil faced rigid foam runs ~R6/inch, while closed cell spray foam runs R6 to R6.4 and provides a better air barrier.Alternatively, you could stand-up a 2x3 or 2x4 studwall in-front of the masonry wall (leave a 1/2" gap between the masonry wall and the studs and spray the stud cavities (and space behind the studs) with closed cell spray foam.  

They nailed 1x2 furring strips to the bottom of the joists, and then used long staples to attach the tiles to the furring strips. 

However, if they then sell it 3 years later when the house is worth $475,000, they pay capital gains taxes on the $75,000 of gain.Now let's say your mom has this house and also several million dollars worth of furs, jewels, classic cars, stocks, bonds and gold stashed under the mattress.  

The exposed brick was not planned, the plaster wall & metal lath was crumbling and the furring rotted!

Think ,insulating, attaching furring to the interior for drywall, limited design parameterers, running ductwork, and mechanicals, asthetics, etc.

@Greg Junge Thanks for your input.

Tiff Junge

The shed fur can get sucked up into the furnace filter.

I think that is likely a little more challenging than she might think with this many fur babies.

I would suggest the tenant purchase a room (or whole house if they prefer) stand-alone humidifier and use that.You can install a humidifier on the plenum of the furnace, they do work, but are another maintenance item (so they do not grow fur during the off season) and, if not functioning correctly, cleaning-up after them can be arduous.