12 x 5 ft granite steps ?
 

do I need to have a french door if my entry steps are 12 ft wide ?

There's hundreds of differant ways you could go with steps that wide.
Sounds more like a porch then a step.
How about a picture?

Most codes call for a railing down the center (anything over 6ft) FYI.
Iron pipe for example.
And you don't need a French door.
Any door at least 3' will do.
Put a 6 or 8' slider in.

A french dooor would look better, be more air tight, less parts to fail.

A pic or at least a better description of what you want to do would be helpful.

FWIW, granite is a bad choice for exterior stairs. Extremely slippery when wet.

The International Residential Code makes no such requirement. :no:

Gdscannell, the width of the door does not dictate the width of the steps. The width of the landing at the top of the steps must be as wide as the steps. But you could put a 3-0 door at the top of a 12' wide stair, provided your landing is 12' wide. The exception to this would/could be interior flights where a landing is not required provided the door does not swing over the stair...Many building inspectors (and people using the stair) would take exception to that.

Polished granite would be no good, that's for sure! But granite is commonly used outdoors for stairs....They hit it with fire to cause the surface to chip away, leaving a fairly rough texture.

Many folks in my area have granite steps, they pay a premium to get them. As Termite indicated, they are not polished granite, the only place I have seen polished granite used is for memorial stones, and once in a while for tile in dry areas. The granite steps are often very rough cut, and are not slippery at all. I have a couple of granite pieces that we incorporated into our brick walkway, they look pretty nice.