The most of the detailers doesn’t know what type of Building they are detailing.
We need to know what type of building we are detailing, which will help our common sense to see if something extraordinary.
Try to visualize the construction sequence, pay attention to construction around your city and try to understand what they are doing.
We start detailing the way construction workers start building. 1st elements to be built has to be the 1st element to be detailed. That helps with the construction schedule as well.
Let's say, a contractor needs to start his 5 story project within a week and he gave you the shop drawings to do. If you start from 5th floor and hoping to finish the project in a week, you are risking the whole project. If you delay everybody will be delayed on the schedule. A concrete contractor will be delayed, and because of the concrete contractor’s delay, the plumber will start his work on a later date, because of a plumber , an electrician will start later, and so on.
So we have to start with footings. 1st element closer to the ground is 1st to detail.
1 - First find out all the bottom of footing elevations. Most of the cases all the footings are level. Find out where footings change elevations, and find the location for step footings. See the example below
And we need to find step footing detail
Now let's do the one at the left side of the column 3, the bottom of footing is changing from -6’-0” to -3’-6”. The difference is 2’-6”, and Max. height on typical step detail is 2’-0” see above.
So we need al least two steps,
Basically we can do any combination we want , but some are practical and some not.
For example, we can do 5 steps at 6”, which would be a lot of work for a concrete contractors. Our aim should be “Min. steps as much as possible”.
So we can do 2’-0”+6” or 6”+2’-0”, most common higher step first,
And show all the elevations for the step.
But there is one more question.
Where should be the location of these steps?
A drawing showing 3 steps, we only needed 2 and where should we place this footing?
Whatever count engineer shows on the plan view is not critical, as long as you follow the typical detail, you can create your own steps. But don’t forget “ Min as possible”.
You can place your steps in any place you want, but as much as closer to the deeper side to minimize excavation. See below picture if you place the steps at column line 4, you will get more excavation as shown in the pink area. More excavation means is more equipment time, more operator time, basically more money.
You can have steps starting right at the edge of column footing or 1’ or 2’ away from column footings. Don’t make it like 3” away or 4 ½” away, try to use 0 ‘ (at the edge of column footing ) or 1’ increments. This way contractors formwork would be a lot easier.