The Biology of Mould

Moulds have a unique, but simple biology. They are dependent on consuming biological material for energy, instead of photosynthesis like plants, but cannot move around like animals. Mould have evolved to take advantage of as much dead organic material as possible.

A moulds colony grows by the expansion of a net of interconnected hyphae called a mycelium. This net serves as a transport mechanism for nutrients and water between the different parts of the colony. This mycelium can be visible if it is very large and can make things that it’s growing on look “furry”

Mould reproduce themselves through spores and these can be released in huge numbers. That means that pretty much wherever you go there will be mould spores in the air. but that doesn’t mean that mould is going to start growing just anywhere. They need a few things to get them active and sprouting.

The most important thing for mould growth is moisture; without it, there’s no way for mould to get going. That’s why most serious mould growth problems in homes and businesses are found around water leaks and other moisture problems. However, to really get going, you need some sort of growth medium. It doesn’t have to be cellulose, but since so many of the materials that we use in our lives are based on wood, it tends to be the most likely material upon which to find mould.

This is why when inspecting for mould growth, we look for areas of damp wood or paper, especially if it’s in a warm spot. In general, mould also needs a temperature over 4 C to grow. If it’s cooler than that and most moulds will halt growth but not actually die. This is why moulds can keep growing through the winter inside the house. As long as it’s over 4 C and wet, mould will get growing.

The simplicity and wide range of food for mould means that once it’s growing it can be hard to halt. Easy to get going, but often quite difficult to slow down or stop. Especially if the original water leak problem has not been solved.

These characteristics make mould very good at breaking down your house, and much of the methods we use to build our homes are dedicated to ensuring that water doesn’t get in and allow mould to grow. Remember that water leaks and moisture aren’t always obvious. Mould growth on attic roof decking is often due to high humidity in the air as opposed to a break in the shingling and plywood. Thus, it’s not always easy to identify the real moisture problem.