An elderly woman has been treated for smoke-related injuries after she escaped her burning Christchurch home overnight.

Fire and Emergency southern shift communications manager Rewi Grace said the blaze tore through a house on Rogers St, Sydenham about 2.15am.

The woman was checked out by St John paramedics.

Grace said shortly after a second fire broke out on the second floor of a factory in Blenheim Rd.

However, sprinklers extinguished the blaze before it took hold.

In the deep south a fire destroyed an unoccupied home on Stewart Island about 1.45am.

Grace said fire crews managed to stop the flames from spreading to neighbouring properties.

Fire safety investigators would be investigating the blazes today.