Roof rats reach sexual maturity in a span of two to five months. They can give birth to litters of 6-20 babies after a gestation period lasting 20-24 days. The young rely on their mothers for nourishment and care for 17-23 days before they can venture independently.
They have an average lifespan of one year and can breed throughout the year, with birth rates peaking during the spring and fall seasons, depending on food availability and favourable weather conditions.