# Foundations: what happens before framing starts

> Soil, rock and water decide the first months of a build. Here is the sequence from survey to slab.

This is the plain-text version of https://blackstone.build/residential/journal/foundations-what-happens-before-framing. To cite or link, use that page.

How a home is built. July 28, 2026.

## The short answer

Before framing, the site is surveyed and cleared, the soil is tested, footings and foundation walls are poured, the walls are waterproofed and drained, and plumbing is placed under the slab. On Birmingham’s hills this stage often takes longer than owners expect, because rock and slope are not fully known until digging starts.

## What is learned from the soil?

A geotechnical engineer drills or digs test holes and reports what the ground can carry. The structural engineer designs the footings from that report.

It will not find every pocket of rock, so a foundation budget should carry an allowance for what the excavation uncovers.

## How is the foundation built?

Surveyors stake the house. The excavator cuts the pad and the footing trenches. Footings are formed, reinforced, inspected and poured, and the foundation walls rise from them.

On a slope, part of the foundation becomes a basement or a walk-out level, and the walls that hold back earth are engineered for that load.

Photo: Mixer trucks and a pump on a foundation pour at first light.

## How is water kept out?

Walls below ground are waterproofed on the outside and drained at the base with pipe and gravel that carry water away from the house.

This work is buried for good. It is inexpensive to do well and very expensive to repair.

## What goes under the slab?

Drain lines, water lines and any floor outlets or conduits are set before concrete is poured. That is why the plumbing fixture locations have to be settled this early.

Photo: The pad and first slab on a wooded lot.

## Common questions

### Why does the foundation take so long?

Weather, inspections and concrete curing each add time, and rock or poor soil can add more. Nothing above can start until it is right.

### What happens if rock is found?

It is removed by hammering or, where permitted, blasting, or the design is adjusted to work with it. A rock allowance in the budget covers the usual cases.

### Do I need a soil test for a house?

For a custom home on a sloping or filled lot, yes. It is a small cost compared with the foundation it informs.

From the [Residential Journal](https://blackstone.build/text/residential/journal).