Moss is more likely to grow on the north side of your roof because it prefers cooler, moister environments. The north side of your roof is typically the coolest and shadiest side, as it receives less direct sunlight than the south, east, or west sides of your roof. As a result, it can be an ideal location for moss to grow.
There are a few other factors that can contribute to moss growth on the north side of your roof as well. For example, if your roof has a low pitch or is shaded by trees, it may be more prone to moss growth. Additionally, if your roof is made of a material that retains moisture, such as asphalt shingles, it may be more prone to moss growth as well.
Overall, the north side of your roof is more prone to moss growth due to its cooler, shadier environment. It's important to be vigilant about checking for and removing moss from your roof to prevent damage and ensure the health of your roof.