What is the minimum depth of footings?

Author: Mittie Prohaska  |  Last update: Friday, October 3, 2025

A minimum of 12”inches deep for all footings and the width will be determined by the amount of stories, 12” inches for a single story, 15” inches for a two story and 23” inches for a three story. This is based on a soil bearing capacity of 1500(psf).

What is the minimum thickness of footing?

In reinforced and plain concrete footings, the thickness at the edge shall be not less than 150 mm for footings on soils.

What is the rule of thumb for concrete footings?

For every 2 feet of adjustment to the width of the house, add or subtract 2 inches of footing width and 1 inch of footing thickness (but not less than 6 inches thick).

How deep are normal footings?

Footings need to be 600mm wide x 1m deep minimum,in some cases depending on ground quality/type,proximity of large trees footings are required to be up to 2m deep.

How far do you dig down for footings?

Depending on your local building code and whether you have a basement, that might be 5-10 feet below grade. Footings are required to be built on undisturbed soil.

How Deep Do Foundations Need To Be For An Extension?

How do I know if my footings are deep enough?

The footing depth, on the other hand, is typically determined by the soil type and the extent to which you must dig before striking undisturbed soil. Still, we recommend that the depth of the footing extends to a minimum of 12 inches after you've hit undisturbed soil.

What is the minimum depth of a footing?

The minimum depth of footings below the surface of undisturbed soil, compacted fill material or controlled low strength material (CLSM) shall be 12 inches (305 mm). Where applicable, the requirements of CBC Section 1809.5 shall also be satisfied. The minimum width of footings shall be 12 inches (305 mm).

What should be the depth of footing?

All foundations shall extend to a depth of at least 50 cm below the natural ground level. The minimum depth of footing on sandy soil is 0.8 - 1 m, for rocky soil, it is 0.05 - 0.5 m and for clayey soil, it is 0.9 - 1.6 m. The minimum depth of foundation for the load-bearing wall is 900 mm.

How close can you dig next to house footings?

Can I excavate near my neighbour? Excavate within 6 metres of a neighbouring owner's building or structure where that work will cut a line drawn downwards at 45 degrees from the bottom of the neighbour's foundations.

What is the frost depth for footings?

❖ Footings are required to extend below the ground surface a minimum of 12 inches (305 mm). This is considered a minimum depth to protect the footing from movement of the soil caused by freezing and thawing in mild climate areas.

Do you pour footings and slab at same time?

Between your foundation walls and resting on top of the footings lies your foundation slab: the giant piece of concrete which makes up your basement floor or subfloor. Each of these pieces must be poured and cure one at a time: a process that can take up to a week for each step.

What is the minimum concrete for footing?

For masonry or concrete construction, the minimum foundation wall will be 6 inches. The minimum reinforced concrete footing thickness will be 6 inches or 1-1/2 times the length of the footing projection from the foundation wall, whichever is greater.

What is the difference between a footing and a foundation?

The footing is what's actually in contact with the ground, while the foundation is the structure that transfers the load to the earth. A simple way to visualize the difference when comparing it to the human body would be to view the footing as the actual feet of the legs and the foundation being the legs themselves.

How deep do footings need to be for a garage?

What type of foundations do you specify? We show standard strip foundations with all our plans. The depth of the foundations are a minimum of 750mm deep but the actual depth is determined on site depending on the soil conditions. The local Building Control officer will advise when he is satisfied with the depth.

How deep should a footing be poured?

A minimum of 12”inches deep for all footings and the width will be determined by the amount of stories, 12” inches for a single story, 15” inches for a two story and 23” inches for a three story. This is based on a soil bearing capacity of 1500(psf).

What is the minimum depth and width of wall footing?

Strip Wall Footings are constructed with typical slab depths between 6”-8” (15-20 cm), footing widths of 12”-24” (30-61 cm), and lengths that vary as needed. Strip Wall Footings are commonly paired with column widths of 6”, 8”, 10” (15, 20, 25 cm).

What is the mix for concrete footings?

A concrete mix of 1 part cement : 2 parts sand : 4 parts coarse aggregate (by volume) should be used for footings. Concrete must be placed within half an hour of mixing. Brickwork – Place your concrete into your trench. Work the concrete into awkward places and corners using a shovel.

What is the minimum depth of footing?

Depth of footing above bottom reinforcement shall not be less than 150 mm for footings on soil, nor less than 300 mm for footings on piles.

How thick do footings have to be?

Required Footing Sizes

In most cases, a house should have a minimum footing of 12 inches wide by 12 inches deep, with foundations that are 8 to 10 inches thick. This should be enough to support house weight and resist lateral soil and water pressure.

Can footings be too deep?

First off: Why you need accurate footings calculations

If you make your foundations too shallow or too deep, there is a risk to the integrity of the build, and a danger that any reinforcement, be it mesh panels or rebar rods, is positioned incorrectly, leading to reduced tensile strength and load-bearing capacity.

What is the thumb rule for foundation depth?

Even if the load is less (for example only 20 tonnes) then also the minimum is 3x3 and depth of footing should be atleast 4 below ground level if not more Reinforcing bar details (minimum) 1. Columns: 4 bars of 12mm steel rods FE 415 2. Beams: 2 bars of 12 mm in the bottom and 2 bars of 10 mm on the top.

What is considered a shallow footing?

Shallow foundations, often called footings, are situated beneath the lowest part of the structure. A footing is the first constructed element of a structure which is built after excavating the ground. In general, the depth of a shallow foundation is less than its width.

How to decide the depth of footing?

The depth of a foundation depends on several factors, such as the type of soil, the type of structure, the design loads, the groundwater level, the seismic risk, and the environmental conditions.

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