What you will notice
A door that rubs
At the top corner or along the floor.
A latch that misses
The strike plate, so you have to lift or push the door to close it.
An uneven gap
Around the door, wide at one corner and tight at the other.
A door that swings
Open or shut on its own.
Windows that bind
When you lift them, or will not lock.
Cracks running up
From the corners of the door or window frame.
Trim pulling away
From the wall around the frame.