If you are unsure, you can also use a moisture meter to test the moisture content of the wood.

I’m taking several tools from a black light flashlight to moisture meter to thermal camera to check everything out and smell the smell for myself to see if I can figure it out.The vent stack for the water heater is a straight shot vertical up, and is a solid piece going to the roof, same for the furnace.

We are in Colorado (near Denver) and noticed moisture in the basement. 

These are simply moisture shrinkage cracks not settlement cracks.  

Plus the moisture buildup.

@Troy Whitney My son is a union carpenter in Seattle and area, he recently worked on a multi story apartment building the developer was using components from a EU country-maybe Poland-they got most of the building up-walls and floors-the building started to accumulate moisture inside the wall components which were very water tight and would not release the liquid.

Safety hazard.7.4.C loose wire ends need to be in box in storage room8.0 foundation- water intrusion visible signs in crawl space. 8.2- undersized wood beams- need reinforcement10.1.a drywall on wall shows wet stains indicating moisture unit 310.2.A unit 3 living room floors are sloped and sagging.10.4.B sliding door unit 2 10.0.C Drywall on ceiling water stain unit 1 over washer/dryer10.1.C drywall on wall peeling paint at utility closets10.6.C electrical issues10.1.D framing wall leak10.3.D back stairs need to be redone for roper stability11.6.A unit 3 exhaust fan not work11.3.B unit 2 bathtub resurfacing needed11.3.C improper materials used at the unit 1 hot water supply11.5.C defective GFCI outlet unit 16.4.A new sump pump + battery

Some of them are obvious needs (broken windows, moisture, etc).  

Otherwise grease and moisture will screw up the walls.