It opened up on a property in the 200 block of Ridings Circle in Macungie.
Authorities taped off the sinkhole which opened up just feet from the back deck.
It's not yet clear what caused the ground to give way or if the residents will be allowed back in.
Elsewhere in Pennsylvania, a sinkhole under Route 202 in King of Prussia caused a water main break.
Repairs forced the highway to be temporarily shut down.