# Gravity load path: slab to foundation

> Follow one gravity load from the slab through the beam, column and footing to the soil. Here is each handoff in the load path and why tracing it prevents errors.

**Category:** Load paths  
**Author:** Elena Marchetti (Structural engineer · Founder)  
**Published:** 2026-05-18

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The gravity load path is the route a load takes from the slab to the ground: slab to beam or wall, beam to column, column to footing, footing to soil. At each handoff the load changes form, from an area load to a line load to a point load to a bearing pressure, while the total force is conserved. Tracing the path is the step before a takedown adds the load up, and StructLoads makes the path visible by showing the load at each element.

## What the load path is

A [structural load](https://en.wikipedia.org/wiki/Structural_load) does not vanish; it travels to the ground along a path of elements, each handing it to the next. Understanding that chain is the foundation of [structural principles](https://www.designingbuildings.co.uk/wiki/Structural_principles): if you can name where a load goes at every step, you can size every element and spot any that has no route down. The load path is the map; the takedown is the arithmetic along it.

## The handoffs, stage by stage

The load changes form at each handoff, but the total is preserved.

| Stage | Element | Load form |
| --- | --- | --- |
| Floor | Slab | Area load, kN per square metre |
| Slab to support | Beam or wall | Line load, kN per metre |
| Beam to column | Column | Point load, kN |
| Column to ground | Footing | Bearing pressure, kN per square metre |

A floor pressure becomes a beam line load, which becomes a column point reaction, which spreads back into a bearing pressure under the [footing](https://en.wikipedia.org/wiki/Shallow_foundation). The load concentrates as it moves down through the framing, then spreads out again at the soil.

## Slab to beam or wall

The slab spans onto the beams or walls at its edges and delivers its load to them, as a uniform strip for one-way action or as triangles and trapezoids for two-way action. This first handoff is set out in [how loads transfer from a slab to beams](/blogs/how-loads-transfer-from-a-slab-to-beams). A bearing wall takes the load as a line reaction per metre instead of a beam.

## Beam to column, column to footing

The beam carries its line load to its end supports and delivers a point reaction to each column. Two beams framing into one column add their reactions to the column's own tributary load, and the column carries the running total down. At the base, the column reaction lands on a footing, which spreads it into the soil, the destination computed in [how to calculate footing loads](/blogs/how-to-calculate-footing-loads). The accumulation along the way is the [structural load takedown](/blogs/how-to-do-a-structural-load-takedown).

## Why tracing the path prevents errors

The path exposes problems a takedown alone can hide. A beam that frames into nothing, a column that lands on a slab instead of a footing, or a support with no route to the ground all show up when you trace the path, before the numbers are added. The same discipline drives post-disaster guidance: [FEMA's wind retrofit guide, P-804](https://www.wbdg.org/FFC/DHS/fema_p_804.pdf), is organised around verifying a continuous load path from roof to foundation, because wind damage assessments keep finding that failures start at whichever link in the path is missing or weakest. The path also shows where load concentrates, such as a transfer beam carrying a column, so you know where to look hardest. Force conservation gives a built-in check: the total at the ground should equal the total applied on the floors.

## When the path bends

The simple straight-down path assumes each column continues to the foundation. Where a column lands on a transfer beam, the path bends sideways before going down; where a podium gathers many columns onto fewer, it redistributes. Lateral wind and seismic loads add paths that are not vertical at all. Those cases go beyond a gravity takedown and need fuller analysis, but the gravity path is still the backbone you trace first.

## Key takeaways: the gravity load path

Load travels slab to beam to column to footing to soil, changing form at each handoff while the total is conserved. Trace the path before the takedown to see where load goes and to catch any element with no route to the ground. StructLoads shows the load at each stage as a preliminary model; transfers and lateral loads need full analysis, and a qualified engineer confirms the design.

## Quick answers

### What is the gravity load path in a building?
The gravity load path is the route a vertical load follows from where it is applied to the ground: slab to the beams or walls that support it, beam to column, column to footing, and footing to the soil. At each handoff the load changes form, from an area load to a line load to a point load to a bearing pressure.

### How does load change form along the path?
It changes at every handoff. A floor pressure on the slab in kN per square metre becomes a line load in kN per metre on a beam, which becomes a point reaction in kN on a column, which becomes a bearing pressure under the footing. The total force is conserved; only its distribution changes as it concentrates and then spreads.

### Why trace the load path before a takedown?
Because the path tells you where load goes, and a takedown only adds it up. Tracing the path first reveals any element with no route to the ground, such as a beam that frames into nothing or a column that lands on a slab. It also shows where load concentrates, like transfer beams, so you know where to look carefully.

### When is the load path not a simple line down?
When a column does not continue straight to the foundation. A transfer beam carries an upper column sideways onto other columns, so the path bends; a podium redistributes many columns onto fewer below. Lateral wind and seismic loads also add paths that are not vertical. Those cases need fuller analysis than a straight gravity takedown.