They used 4 mobile home anchors down each side, they screwed em in with a gas powered motor, then secured them with 3/4 inch bolts ... a carport company... Carolina carports .. came out, did the job with a crew of 3, was gone in 2 hrs .... they was one of the few that would build to your size /specs /// a standard size is 18 wide by 21 deep ... this is 18 wide by 15 deep, .... 800 bucks, done and gone in 2 hrs ... loved it ...