Question: Is it true that light-colored brick undergo more moisture expansion than dark-colored brick?
Answer: I am not aware of any accurate method to predict moisture expansion based on the color of brick or any other physical properties of the units. I have investigated many buildings that have cracking problems associated with unusually large moisture expansion of the brick. Some of these brick were dark colored, and some were light colored. The rate of moisture expansion depends on a number of factors, including the composition of the clay, the firing temperature, and the exposure to weather in the completed building.
Dark-colored brick have greater thermal expansion than light-colored brick simply because they absorb more solar radiation and so are heated to higher temperatures. I have measured surface temperatures of brick exposed to direct sunlight greater than 160° F. Because light-colored units reflect more light, they will be cooler.
The designer should estimate the magnitude of brick masonry expansion using the equation in BIA Technical Notes 18A. Joints must be sized and spaced to accommodate the expected magnitude of moisture and thermal expansion.