Shallow foundations are commonly known as open or spread footings. Open makes reference to the fact that the foundations are constructed by first excavating and removing all the earth until the bottom of the footing is reached, then building the footing itself. During the early work stages, the whole footing is visible at a glance, that’s where the name open foundation comes from. This footing type is designed so that each one takes the overall load of the column and spreads it out over a large surrounding area. The goal is that the actual weight on the terrain does not exceed the land safe weight bearing capacity.

In cold climates, shallow foundations must be protected from freezing. This is because water in the soil around the foundation can freeze and expand, thereby damaging the foundation. These foundations should be built below the frost line, which is the level in the ground above which freezing occurs. If they cannot be built below the frost line, they should be protected by insulation: normally a little heat from the building will permeate into the soil and prevent freezing.

When we consider the system that withstands the weight for houses or commercial buildings, as is in most cases, it begins with the foundation. But you will find out that even a foundations themselves need a foundation to start with. The very first component when preparing the vertical backing scheme is the foundation footer. While not all footings demand iron bar reinforced concrete, we’ll focus on two types that do require it: grade beam and spread footings.

When the building goal includes endurance and long life, then you can’t forgo the investment in a proper foundation, especially in areas frequently assailed by natural forces such as high winds, earthquakes and/or flooding. Together with the footings, building construction foundations also fight against differential settlement, where the building settles at different rates on different points of the building causing it to thwart. In addition to avert cracks and structural destruction that occurs from extreme differential settlement, building foundations also:
Transfer loads to the various footings and/or directly to the earth itself
Anchor the building structure to withstand wind, floods and/or earthquakes Maintain the basement dry with proper sealingDisconnect moisture-averse building materials from the ground Depending on a variety of environmental conditions at the building site, reinforced concrete footings have the capacity to support the foundation with the maximum amount of strength.

Footings offer several essential benefits for foundations as follows:

• They provide a level surface upon which to construct the foundation.
• Also, they offer resistance to the upward-acting forces from the soil opposing the downward-acting forces of the building weight.
• While footings have greater widths than the foundation itself, they serve to distribute the building load to the terrain upon which the building is sustained.
• Footings contribute strength to the foundation system in weak areas of the soils. Shifting soft soils push on foundation walls above the footing vertically and laterally.
• Footings absorb part of the pressure and reinforce the foundation against unstable shifting terrains.
• Footings allow the foundation to sink far enough below grade to avoid frost depths where heaving and thawing cause uneven settlement.

In essence, footings help prevent foundations from sinking or twisting. They also are the primary elements that help the foundation to remain perpendicular to the ground and maintain buildings straight up. Reinforced concrete can underpin the foundation in two different styles from many options for footings. Each of these styles work best for certain environmental conditions. These are Grade Beam and Spread Footings.

Whenever a foundation should extend deep into the earth due to unstable soil or height differential, a grade beam footing may be the best choice. On steep slopes, in shifting soils and where the design calls for a pier or post foundation, grade beams are the perfect application as they span the distance between the load-bearing concrete piers. The grade beam would either rests directly over the soil or it’s accompanied with its own pilings for backing. The grade beam trench is dug and poured with no less than eight inches wide and equal to the depth of the span between the support footings, a continuous grade beam footing will evenly distribute the building load to the ground and/or to its bearing points where their bases distribute the load to the terrain.

Spread footings work best in shallow foundations where the soil is well-compacted, a bedrock is set in place and the soil is stable. These footings are also known as “T” footings (when the T is upside down). Spread footings are set to rest directly on the soil and are wider than the foundation wall by several inches. You can determine the width and thickness of the footing according to the load it will bear above and the type of soil below. These footings are most commonly used in residential applications or one-story commercial buildings. Spread footings often don’t need to be reinforced to meet city code. It is good practice to use nominal reinforcement for flexure preventive measures. The lower the load-bearing capacity of the soil, the wider the spread footing needs to be to prevent erratic settlement. Spread footings are also poured below the frost line. The footers make for a level and smooth line upon which the concrete foundations are then poured to form a continuous wall backing the perimeter of the building.