setting finish floor elevations

[johnhan76]

This is how I set finish floors in residential subdivisions- I am wondering if this is what everyone else is doing.

1. Draw house.
2. Find highest contour line that intersects house.
3. Add 2' to this to determine minimum finish floor elev.
4. Make sure that this is 1.5' higher than road if the drainage is going towards the road.
5. Make sure that I can get the sewage to the main.
6. Make sure it is 1' above flood stage.

Thanks

 

[francesca]

We only set finished floor elevations on lots that have 100-year flood elevations encroaching on the lots. In rare exceptions, we'll set a FFE for a lot if we're having difficulty with getting adequate fall to the sewer.

When designing our sewer, we usually aim to be 3' lower than the contour passing through the middle of the building pad (around here we assume a 50'x50' building pad behind the front set back).

It could be that your local planning commission requires FFEs on all lots, but ours only requires it if the lot is within a 100-year flood zone. We specify one foot above the 100-year.

 

[Maury]

Our process is essentially the same as johnhan76, except that foundations are set a minimum of 2' above the 100 year flood elevation. Grading plans for new subdivisions must show the foundation elevations on all lots. The grading plans have to include overland flow routes throughout the property, with elevations along all lot lines. Grades are not left to individual builders.