Doors and windows another way to test the seriousness of a wall crack is to open and close internal doors to bedrooms and bathrooms and evaluate whether the doors stick.
How to detect cracks in window and door.
Turn off the furnace and water heater and turn on exhaust fans.
Hold a lit incense stick by windows outlets doors and any other suspected areas.
Stress cracks start off small and then expand and grow across the glass.
In most cases the crack will follow a curve in the shape of an hourglass.
If smoke blows sideways you likely have a leak.
Inspect windows and doors for air leaks.
Check to see if the caulking and weather stripping are applied properly leaving no gaps or cracks and are in good condition.
Another option for detecting air leaks is using an infrared thermometer which is a non contact thermometer that can measure the ambient air temperatures around window and door frames.
The most common cause of these stress cracks is extreme temperature fluctuation.
The windows cannot withstand the pressure of these scenarios and will crack as a result.
You can usually find them near the edge of the window glass.