Each unit has there own electrical box and has some aluminum wireing copper wireing in them with knob and tube after the panels.

Just got a bid on  replacing 32 double hung windows with energy star windows, half screens, with argon gas windows, aluminum wraps, tempered glass in the bathrooms.Initial bid came in at $18K, doing it two units at a time, but said he would knock it down to $16K if I did the entire job at once.  

I currently own three properties in southeastern Wisconsin and am looking to add a few more in 2016.

I navigate throughout Southeastern Wisconsin pretty much,so I'll definitely be in touch once covering that area.Thanks so much & have a great day.

Here are some before/after pics of what I did (I forgot to take before pics of the finished unit so including before pics of the mirror-image second unit I'm working on now):(took out a wall to make it appear larger, enlarged the kitchen to add dishwasher, chalkboard wall, built-in counter-height table and put a sliding barn door on closet)(added pallet wood accent wall, aluminum backsplash, built-in wine rack, deep sink with industrial faucet and stainless doors on upper cupboards)(replaced tub with large stand-up tiled shower and shower head with body jets)(added a pallet wood accent wall to the larger bedroom)(added a coffee sack accent wall to the smaller bedroom)

I am a realtor in South Eastern Massachusetts and have been in real estate for over 25 years. 

Thanks for sharing your wisdom.Using the chimney stack depends on your city code, here in Utah if it's and aluminum vent piping for the stack it's legal to tie into it, if it's just a straight old school brick 2X3 chimney box you can't demp the water heater exhaust into it. 

There are always options to put aluminum coating over to reseal the metal.

@Jay Y.You can get low-e windows in aluminum housings and those are little bit cheaper.  

I personally only like properties 1950 or newer, but also still need to scrutinize to rule out properties that have Poly-butyl plumbing or aluminum wiring, both of which require immediate replacement due to defects or fire concerns.