A van has ample interior space that makes installing additional seating a simple task. You have more room to work, which can simplify the installation process. When adding extra seating to your van, it is imperative you use only chairs designed for your vehicle or compatible aftermarket seats. Do not install a homemade chair you made yourself without the help of a professional or you may put yourself and your passengers at risk.
Open the front doors of the van or the sliding back door. Examine the floor of the van for bolts or tracks that you can use to install the seat. You may have to pull back the floor carpets to determine the location where the extra seat can be installed.
Remove the bolts from the floor where the seat goes by crawling under the van and using a wrench to loosen the nuts on the underside of the vehicle. If your van is equipped with skids on the floor, you won't need to use bolts because the seat will sit directly on the skids and snap into place. If you van has floor bolts, lift them out and set them aside for the moment.
Lift the seat into the van. If you can't fit it through the front doors, push the seat through the large back door of the van and slide it into position. Align the holes in the mounting bracket on the bottom of the seat with the holes on the floor.
Thread a washer onto the bolt and push the bolt through the seat's mounting bracket and the floor. Thread a second washer and a nut onto the loose end of the bolt on the underside of the van and tighten it down with a wrench.
Push and pull on the chair to make sure it is securely attached to the floor. If it shifts too much for your comfort, tighten down the nuts further on the underside of the vehicle.