Construction sites can be dangerous places and places that have a lot of expensive equipment. So it's important to make sure unwanted visitors are kept out of all construction sites and the best way to do that is to post signs around the perimeter of the job site warning people to keep out. Many time insurance companies will require construction companies to post no trespassing signs on all job sites. Sign.Builders offers a wide variety of Construction Site Under Surveillance and No Trespassing signs. You can order those signs on both plastic (for short term use) and metal (for extended use).