The amount of room that you will need for a wheelchair lift in Smithfield is one of the issues that you need to take into consideration when planning for the cost of installation. You can discuss this with the contractor handling the installation for you so that they advise you on the appropriate size, and what it will cost. In most cases, the size you need will depend on the platform changes, and more importantly, the purpose of the ramps. On average, the standard wheelchair lift is designed to support 4.5’ x 5’. If you need anything smaller or bigger than this, you might have to get it custom designed, which means that you will have to incur additional costs.