How to Build a Pier and Beam Foundation

A pier foundation is frequently used for building homes. A pier foundation comprises concrete piers that are placed deep into the ground to tolerate the weight of the structure.

The concrete and wooden posts are used to cover the concrete piers and along the tops of the posts there are horizontal wooden beams to form a bed on which the structure is constructed.

The pier foundation does not stand directly on the ground but instead normally elevated about 18 inches, developing a crawlspace underneath the home.

The pier foundations can be constructed easily and are inexpensive as compared to other foundation systems. It is best suited for smaller buildings but is not recommended for the homes constructed in earthquake and hurricanes prone areas as pier foundations are not set deep into the earth. Besides, the homes constructed over pier foundations are likely to form sagging and creaking floors.

Large-diameter The bored piles with large diameter are known as drilled piers, drilled shafts, and occasionally drilled caissons.

Types of Drilled Piers: Drilled piers are categorized as four types. The construction method is same for all but the differences are found in their design assumptions and in the mechanism of load transfer to the adjacent earth mass.

• Straight-Shaft End-Bearing Pier
• Straight-Shaft Side wall Shear Pier
• Straight-Shaft Pier With Both Sidewall Shera and End Bearing
• Underreamed or Belled Pier

Straight-Shaft End-Bearing Pier: Straight-shaft end-bearing piers are supported with end-bearing on strong soil, “hardpan” or rock. The overlapped soil is supposed to provide nothing to the support of the load enforced on the pier.

Straight-Shaft Side wall Shear Pier: Straight-shaft sidewall friction piers move across overburden soils that are supposed to bear none of the load and infiltrate far enough into a set bearing stratum to form design load capacity through side-wall friction among the pier and bearing stratum.

Also Read: Benefits of Pier and Beam Foundation

Straight-Shaft Pier With Both Sidewall Shera and End Bearing: The construction process is same for a combined straight shaft side-wall friction and end bearing piers but with both side-wall friction and end bearing assigned a role in bearing the design load.

When transferred into rock, this pier is described as a socketed pier or a “drilled pier with rock socket“.

Underreamed or Belled Pier: Belled or under reamed piers contain a bottom bell or underream figure. The maximum imposed load on the pier top is supposed to be borne by the base.

Benefits Drilled Pier Foundations:

• The piers with different lengths and sizes are built at the construction site.
• The construction process is very fast as the construction equipment is generally mobile.
• Due to the greater diameter of the shafts, proper inspection of drilled holes can be done.
• A single drilled pier foundation can bear very large loads and there is no need to use a pile cap.
• The drilled pier is suitable for different types of soil conditions.
• Modifications are made in the design criteria throughout the progress of a job
• Ground vibration generally found with driven piles does not exist in drilled pier construction
• Bearing strength is raised by underreaming the bottom (in non-caving materials)