Building a bridge in The Sims 3

First, build a foundation two tiles wider than the desired width of your deck.

Next, tear down the center of your foundation. This is what will represent your bridge.

Add the flooring of your choice to the demolished plot.

Remove exterior foundation tiles across the width and not including flooring.

Place the stairs that will allow access to your deck.

Design the surroundings, add a pond underneath and you are the happy builder of a beautiful bridge