I'm trying to find out how much are engineering firms charging for subdivison design per lot. Includes preliminary plat and construction plans. Surveying fees will be extra. I'm in North Carolina.
We base our fees on the total acreage of the project (in addition to project location, scale of project, and a host of other things). Lot sizes can change and vary and the number can go up or down over the course of a project so it doesn't make sense, to me, to charge (or determine fees) based on the number of lots. Then again, maybe I'm in the minority.
Design fee is 12-15% of the construction costs, (excluding plat filing and lot pins):i.e. grading, storm sewer, Sanitary sewer, Paving and water lines. I will take my fee in lots so as to show good faith in the developer. A good design sells quickly and usually escalates in price.
In my area design fees for subdivisions run anywhere from $750 to $1,000 per lot. This includes surveying. These subdivisions are typically 1/4 acre or less lots.