Pin Piles – Deep Foundations

Pin Piles Overview

Pin piles, also known as mini-piles or micro-piles, are narrow driven piles. They consist of a steel pipe casing, steel rebar for added strength, and cement grout. Their diameter differentiates them from pipe piles. Pin piles can range between 2-6 inches in diameter. Pipe piles have a diameter of 8 inches or more. The Seattle Department of Planning and Development has more details here. Depending on the project, pin piles can range from 5 feet to 60 feet long. Pile length is chosen based on how deep the soil is between the soil and harder bedrock.

Pin piles can be used to strengthen foundations in poor soil conditions to prevent settling. They can be used to restore support when a building outlasts its original foundation. They are also used to support structures damaged by soil movement. Some causes of soil movement can be from earthquakes or landslides. Their capacity ranges 2 to 15 tons, based on the diameter of the pile.


Deck supported by pin piles

Deck supported by pin piles

Pin piles are less expensive to install for deep foundations than thicker driven piles or drilled shafts. They can be installed in soils where drilling wider shafts is not feasible. Unlike cast-in-situ piles, they can be driven through soft or wet soils to hit deep layers of rock. Construction sites with limited access aren’t a problem for the smaller machines needed to install pin piles.


Given their small diameter, pin piles are used for smaller projects with lighter loads. Most projects will be for smaller single-family homes or deck support. Pin piles can deform under heavier loads, reducing their strength.  They are driven into the ground using hydraulic impact hammers. These hammers cause some noise and vibration when used.

Call us today! Learn how Pearson Drilling’s pin piling services can suit your project needs.