I would start by paying the second GC to write up a short statement explaining their expertise, what they found when they were awarded the job, what they did to fix the existing work, and attach a copy of their invoice.

Now the HOA asks me to apply a padding/underlayment under the floor, but the floor I purchased already comes with a pre-attached underlyament....Now I am not sure how to handle this issue, I just bought some area rugs to reduce the noise for now...

Enter a maintenance request, assign a vendor, and attach a fake invoice.

@Peter Sanchez Thanks for the replyI plan on using it as a house hack (so I'll be living upstairs) and the house is a semi attach home (share one wall). 

Our plan is to divide it into two sections: a 3/4 bath with a small standing shower (32 x 32) attached to the master bedroom, and a guest bathroom with a full-length tub (60 x 32), totaling around 40k for the project.

I am attaching a very rough drawing of what I am dealing with.

Also, there is no visible mold and no mold smell in the basement (there is a little on the caulking beneath a single pane picture window upstairs which I'll deal with).That didn't sit too well with the tenants as they have been looking online and finding information about how dangerous it might be, and it didn't help that the first report that I had done the inspector attached a boilerplate message recommending a full HVAC cleaning (ducting is 1 year old) HEPA vacuum, air scrubbers, double washing everything in the unit with bleach, etc. so now the tenants are being fairly combative and insisting that more needs to be done.

Attached is a picture and walkthrough to give some ideas but is anyone aware of what kind of paneling is used on this wall and where to buy (picture)?

Hi All, I have a few large garages attached to a small apartment building which are allowed for storage uses.

Regardless, she said she could send me the attachments for inquiry removal in the next 5 minutes.