How and why do buildings expand and constrict?

Question

Not sure what category this falls under but I’m curious. My bad if my flair is way off.

In: 1

Answer 1

All materials change size with temperature, as their molecules’ vibrating more or less changes how tightly packed they can be.

Wood and other materials (but in buildings mostly wood) change size with the moisture content of the air. More moist air causes them to absorb more water and expand to hold it.