Do you have a deck over the top of your room?
One of the most common types of leaks we find is caused by waterproofing membranes not correctly installed underneath the doors leading out to the deck… any type of door.
One of the main contributing factors to this problem is the level of the deck. Under the ‘leaky building code’ of the late 90’s and early 2000’s, many homes where built in such a way whereas the deck level was very similar to the inside floor level. If there is any pooling of water on the deck, wind driven rain in the direction of the door, or a blocked drain (normally with leaves and debris on top), then water tends to rise up and over the raised lip of the butanol, then down onto the ceiling below.
Another common trait of a leaking deck is when the cladding runs down and touches the deck. Water will simply soak up the cladding then saturate the bottom plate and then potentially drip down onto the ceiling below.
Here is a sample infrared thermal imaging photo we took in a home recently: