The larger lot required could be a part of it. And a great deal depends on the load bearing structure of the home. A garage door in a gable end will not need the beefier header that one in a side wall will. The additional steel or LVL could be half that cost. And the additional framing labor the other half.

Did you ask the builder?

Besides the possibility of a bigger lot (which would take up most of it), there are implications for the foundation, framing, and all the finishes. Also, is this a subdivision builder? If they have a certain set of plans and models they work with, changing anything has production timeline implications, so it could be almost a 'fine'.

Thank you all for your input! Ichabod Crane, the side entry is listed and pictured as an option, so it shouldn't affect the timeline, I wouldn't think? Live_wire_oak, your suggestion regarding the additional steel, framing labor, etc. could definitely be part of it. The lot size would remain the same, however. Mrspete, love your comment, this is exactly how I've felt throughout the pre-building planning process!

There really isn't much of a structural change for a side entry. In fact, in a traditional (gable end) it's probably easier to have the garage door in the side. As pointed out, the major cost is the additional paving and possibly lot size to get you around to the side (unless you happen to have a corner lot).

If you're building with a tract builder or one of the large national builders, it has nothing to do with what it actually costs. You choose a stock plan and they make their money when you make changes to their stock plan. In some cases they charge double what it would cost you to buy the change if you weren't using them.

It sounds right for a side load in my area.. I assume yours would require windows (1-3) on the front of the house? I assume you'll have a concrete parking pad and with a side load you'll need more yards of concrete to accommodate backing vehicles out of the garage. Around here, it's well over $100/yard. A two-door versus one-door garage also makes a difference in cost.

My builder had my stock plan updated and changed to garage to a side load. Of course we paid for the new plans, but his original estimate to us did not change. His bid was for $100/per sq ft. and that is what we paid.

I don't know how anyone could estimate the cost difference between two different designs without seeing both designs. We don't know how many cars, what might be above it or to what extent the garage is part of the house structure. Perhaps the roof design changes enough and he has to pay an engineer to design the structure and a drafter to change his standard drawing so he can get a permit.

Can anyone tell me what my basement will cost...? It's a joke folks!