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Homeowner’s Guide: Differences Between Trenching & Excavation


During landscaping, building foundations, and repair or installation of new utility lines, professionals use two techniques-trenching and excavation. Most people use these terms interchangeably, but they refer to two different excavation methods, each with pros and cons. As a homeowner, you need to know the differences between the two techniques to help you select the right one for your property and budget. In this guide, we shall explore the trenching and excavation basics, the differences, and how to choose the best technique recognized in all of Vancouver.

What Is Trenching?

In construction, trenching means removing dirt and rock from the ground, creating a narrow hole. In residential construction, trenching builders use it for installing plumbing, heating pipes, or electricity cables. Trenches come in different shapes depending on their purpose.

•   Straight Trenches

A straight trench has parallel sides at right angles to the bed or base. Contractors use linear trenches when they have a limited area to work on, such as near buildings or roadways.

•   Sloped Trenches

Sloped trenches have angled sides to prevent cave-ins. The trench depth, soil type, and sometimes the length you need for the trench determine the slope angle. These trenches are handy during new construction types where surface area is not an issue.

•   Benched Trenches

A benched trench consists of sides cut away to form stair-case-like steps. The type of soil determines the height of the steps or vertical distances.

•   Bell-Bottom Pier Trenches

This trench has a narrow top compared to the bottom, making it bell-shaped. The sides slope inward.


Excavation is the process of removing soil or rock material from the ground to form a cavity or hole. The contractors often excavate via machinery. Typically, excavation uses excavators, loaders, backhoes, tractors, or dozers. Excavation involves much more than scooping out earth or excavating rock and is necessary for a solid foundation of your house. Excavation falls into two categories:

•   Mechanical Excavation

This type of excavation uses heavy machinery that uses hydraulic power, such as backhoes, excavators, or dump trucks. Excavation can also include digging by hand using shovels and axe picks. This method is helpful in large construction sites where there is no danger of damaging underground utilities.

•   Vacuum Excavation

This excavation uses suction and is helpful for small jobs where less material needs moving. Vacuum excavation is an effective and low-impact digging technique called suction excavation or soft dig. This excavation technique breaks up soul and rock via pressurized air and then suctions it to remove it. Vacuum excavation helps clear debris in a home construction site, trench digging, remote excavation, and sewer line repairs in an existing home.

Differences Between Trenching and Excavation

Trenching and excavation have a few differences, such as:

•   Length and Depth

A trench’s depth is greater than the width, not exceeding 4.6 meters or 15 feet at the bottom. Excavations can be of varying lengths and depths depending on the type of construction.

•   Size

A trench cannot exceed 15 feet, but an excavation can be any size and either shallow, deep, wide, or narrow.

•   Safety

In a trench, you need protection measures against cave-ins while working in one. You do not necessarily need protection in an excavation unless it’s over 1.2 meters or 4 feet deep. However, a competent person must gauge the excavation and declare it safe from cave-ins.

Depending on the soil type, some excavations less than 1 meter deep are safe to enter without protection. Some excavations may also pose risks of caving in. The weather and ground conditions or work activities on site also play a part in the safety of the trench or excavation.

How to Decide Whether to Use Trenching or Excavation for Your Project

The soil type matters a lot before you decide between trenching and excavation techniques for your project. A competent and qualified soil technician must check the soil on your site and advise you on the way forward. There are ‌four types of soil:

Type A

This soil is dense and very strong, needing an excavator to penetrate it, and also the most stable. When you excavate this soil, the sides look smooth and shiny with no water seepage. When the soil gets sun exposure, it loses its luster but remains compact.

However, exposure to rain makes the soil crumble along the edges. Examples are the clay, sandy clay, clay loam, and sandy clay. When Type A soil has fissures, water seepage, or has experienced some type of disturbance, it does not fall into the Type A category.

Type B

This soil is very dense and stiff, with medium strength. You can easily penetrate it with a pick axe. Type B soil looks damp after a fresh excavation, and the sides are vertical for a few hours. After some exposure to air, tension cracks appear, with the soil cracking and falling inside the trench. Type B soils include silt loam, silt, angular gravel, or soils that could fall under Type A but have experienced some disturbance, water seepage, or cracks.

Type C

Type C soil is the least stable for trenching and excavation and could be stiff, firm, or compact and have a loose consistency. This soil could be previously disturbed or excavated soil or backfill. You might see signs of water seeping through or the surface cracking. This soil has low strength, and when dry, the trench sides cannot stand vertically but fall into a 45-degree natural slope. With this soil type, the cave-in risk is high, and you must use a protection system. When Type C soil gets wet, it dries fast, with chunks falling into the trench. Examples include sand and gravel.

To avoid legal issues, you must always confirm what the legislation in your area states about which protective systems you should use. Now that you know the differences between the two, it gets easier to decide which of the two constructions to choose for your construction.

More on this topic:

Building a New Home From Scratch – An Overview

Building a New Home From Scratch – An Overview

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