I see these all the time. If you wonder why your floor is sagging, start by looking at the main support beams. Are they compressing at near the columns? This is another photo of another compressed beam that has sagged about 1″.
If you are wondering why your house is settling in the middle or why there are cracks in the drywall, the answer may be that the main beam has compressed. When the shims are undersized or the wood is damp (from high air moisture levels) the wood of the main beam can compress. This causes the floor to settle and move downward. 
If your kitchen sink (or any sink for that matter) doesn’t have a P-trap under it, you will notice some strange odors coming out of it. Traps are inexpensive… put one in. They’re required!
Kitchen sink does not have a trap.
If a pesky floor joist is in the way… just cut it out. Why bother supporting the joist. The home owner might notice the floor sagging or tilting, but the plumber decided to let someone else worry about that.
When installing roof vent flashing (boots), you might as well do it properly. The shingles should lap down over the boot’s flange at least 1/2 way down. If you don’t, there’s an increased chance for leaking.
Do not cut trusses; bad things can happen
I don’t want to be sitting here when the sparks begin to fly!
This is truly a Hot Seat! How many ways can you see in this photo where you could be electrocuted?
