In addition to the extra layer of drywall and sound insulation there are vibration clips that are installed under the joists and then a metal furring channel is installed running the length of the ceiling.

Are prices above to replace furnace, cooling coil and condenser?  

Get the duct cleaned and get the ac coil cleaned if not already  that worked for me on the last place I had like this 

So I grew up with a contractor as a father that built design metal buildings.

It could be patched for around $2000  for a new a/c unit and an a -coil for new refrigerant but why patch a 30 year old air handler? 

We live in Texas and plan on building metal frame homes.  

Im familiar with metal steel material price sq f.Heres what i see; attached is the photo: 10; 1,000 sq ft retail leases @ 1,000 dollars for 10 years. 1 centered anchor.City officials may help with rest if i asked residents to sign a petition non accredited people to put up a shopping center.

Also the 2nd house has an addition built to be a closet for a bedroom that is held up by two metal support beams but it still slopes and feels as if you could break through the floor if you jump on it hard enough. 

It's not shingles and it's not metal.

If you're not lucky and it's not copper coming in, with the age of the building, it's possible/probable you have a malleable soft metal water pipe that you're not exactly sure what it is when it comes to legal disclosures (thus the non-permit work, City would make you replace the malleable metal water line if you pulled a permit).