Foundation Piers are one of the most important features of most foundation designs. Homes built on soil with a high “PI” (plasticity index) are likely to require piers to avoid foundation problems in the future. A qualified foundation engineer should have reviewed your soil test, structiural plans, site plan, and other documents to determine which foundation type is suitable for your home. Note that some engineers may design your foundation without piers depending on your job specifics. If foundation piers are required by your engineer, they will be sized by your engineer and indications placed on your foundation plan as to their required locations.
In most cities, a pier inspection is required to ensure that the piers are drilled to the proper depth and width. DO NOT POUR YOUR PIERS without the city inspector on-site to approve the piers.
Also, do not pour piers if there is standing water on the ground or if rain is expected. Piers MUST be dry to pass inspection.
OPEN PIERS ARE AN “ATTRACTIVE NUISANCE” and are dangerous to curious children and adults. The builder must take all precautions to prevent someone from falling into open piers! Usually, piers are poured immediately after they are drilled and inspected.
Items that you should check:
- Address is posted
- Pier ‘Spoils’ are Removed From the Building site.
- “Spoils” is what the dirt from the piers is called. This dirt is not acceptable for your foundation and should be removed from the jobsite. Note that in some cases, this dirt may be acceptable as ‘fill dirt’.
- Mark Piers
- If the home is to receive piers, a surveyor or qualified technician should layout the position of each pier. Special attention should be paid to this step as piers go deep into the ground and cannot be moved or removed. Any mistake on piers will be expensive to overcome later.
- City Inspector is On Site to Review the Pier Pour
- The pier holes must be inspected as they are drilled to ensure the proper depth, width and bell size. The inspector will approve each pier individually and watch as the concrete is placed.
- Piers are Drilled to the Depth Stated on the Plan.
- Typically, the piers are uniform in depth. Some engineers may allow for pier depth to vary enough to reach stable soil – check with the engineer.
- Pier Shaft Diameter is Correct
- Pier Shafts are usually uniform in diameter. However, it is not uncommon to see certain piers vary in size to accommodate excessively large foundation loads.
- Ensure that the piers are sized correctly.
- Pier Steel Should be ‘Made-Up” Prior to Placing Concrete in the Piers.
- Typically, pier steel will be 2 to 3 rods of steel at the length specified. The Rebar is placed inside pre-made rebar stirrups in a triangle shape and secured with ‘wire ties’. The stirrups are at regular spacings designed by your engineer – typically 1-2 feet on center.
- Pier Concrete Mix Matches the Engineer’s Design and No Excessive water is added.
- Concrete may be ordered in a wide variety of design strengths and mixes.
- Check delivery tickets against the engineering to make sure the concrete is correct.
- NOTE: Excessive Water WILL WEAKEN your concrete. Concrete should be delivered to your jobsite at the required ‘slump’. If necessary, your engineer may allow a small amount of water to be added to your delivered concrete to make it more workable. 1-gallon-per-cubic yard of concrete is usually all that is allowed.
- Pier Steel is Placed Properly in Each Pier
- Pier steel should be placed squarely in the center of each pier and should not rest on soil. Concrete should be placed on all sides of the steel. Typically, pier steel will stick up above the ground to be tied-in with the foundation steel later.