step footings
step footings
(OP)
In the case where the grade slopes I spec step footings to create a situation where the footings are always the required min distace below grade at all points. The steps by code are a max 2' rise and a min 2'run. A contractor wants to set the footings on a slope to match the slope of the grade outside so that the footings are founded the required distance below grade at all points . Does anyone have a problem with that.






RE: step footings
RE: step footings
This is not a good scenario and I would never do it. Flat footings are good.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: step footings
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: step footings
RE: step footings
Unless the top of wall is sloped parallel to the grade, sloped footings result in variable length of bars which is a bit of a nuisance but doable.
BA
RE: step footings
Strip footings with proper limits on the rise and run of the components to meet the slope requirements have been sucessfully used for centuries.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: step footings
Nevertheless, sorry for any confusion.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: step footings
RE: step footings
RE: step footings
Level (usually assumes flatness) is a surface that does not slope, or in common terns, does not drain.
Either flat or level footings can be acceptable, depending in what the materials above it are. A flat footing is not very good for setting precast or long masonry walls on because of the variations in elevation depending on the location and can require large amounts of leveling materials to maintain truly vertical elements above. You have no idea of the elevation at a point unless you either have an elevation shot or want to rely in a measurement from a known point to use in a calculation based on the slope.
Some types of construction may require a specified distance below grade (as in frost protection) and the footings can be built cheaply, but the walls or elements above the footing can be costly to build and may not perform as expected.
Step footings with level tops and even reasonable flatness are proven and can be the best approach for most structures.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.