3-Tier degin application doubt

I've an application that uses 3-tier desing, in this applicatiom I created a class that represents my own type of data.
My type is used in the Business layer as much as DataAccess layer.
In my application Solution I've 3 projets: Web Project, Business Project and DataAccess Project.
I create the fourth project to put the class that contains my own type and the Business and the DataAccess references this fourth project.
I want to know if is the best thing do to or I'll have to delete the fourth project and duplicate my type's class in the Business and the DataAccess project?
It's normal to find/develop an application like this?