A man has escaped serious injury after his semi-trailer crashed into a house in northern Sydney this morning.

The truck went off the road on Sefton Rd in Thornleigh at around 11am this morning.

There wasn't anyone inside the house however it's believed the truck driver has a fractured head.

A building inspector is en-route to the accident to examine the house and a heavy tow has been ordered to remove the truck from the house.

A truck crashed into a house at Thornleigh. Photo: 7News