Photograph of a pre cast concrete and wood modular foundation Pre-Cast Foundation defects of occurrence: damaged pre-fab building foundations

  • CONCRETE PRE-CAST FOUNDATION DEFECTS - CONTENTS: Pre-Cast Concrete Foundation Defects listed, described & explained. Foundation defects of occurrence: things that happen that cause damage to building foundation walls or slabs. Photographs of pre-fab or pre-cast foundation damage patterns and types
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Pre-cast concrete foundations:

This article explains How to Inspect & Diagnose Problems in Pre-Cast Concrete (Modular) Foundations - pre-fab foundation wall sections such as pre-cast "superior wall" foundations, precast concrete walls, how they are placed, how pre-cast concrete foundation walls are sealed, footing alternatives for pre-cast or modular foundations, and concerns for proper caulking or sealing between precast concrete foundation or wall sections.

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Examples of structural & other failures in Pre-Cast Concrete (Modular) Foundations

Photograph of a pre cast concrete and wood modular foundation Photograph of a pre cast concrete and wood modular foundation

Pre-cast foundation walls such as the Superior Walls R-5 ™ or Xi ™ (extra insulation) systems provide sections of concrete foundation walls which are lifted into place and bolted together, often sitting on a simple gravel footing-base, or properly installed, on crushed stone footings [2009 IRC section 403.4.1].

Superior Walls technical director Robert Hare points out that Superior Walls panels use specially formulated polyurethane sealant to seal these joints.

From some manufacturers, (not Superior Walls) the wall sections are sealed, typically with gaskets or caulk or both.

These are excellent building products with a proven track record, but as with any building material or procedure it's important that the precast concrete wall sections are properly transported, stored, installed, connected, and sealed, and that they are supported properly on footings or gravel properly prepared.

The defects we've observed were in pre-cast concrete foundation wall installation and did not involve evidence of structural failures.

  • Incomplete sealing between foundation sections, leading to later basement leaks and water entry
  • Poor modular foundation section alignment, poor sealing between sections, particularly at building corners, resulting in foundation leakage
  • Inadequate footing drains around the pre-cast concrete foundation (or none), and/or inadequate roof drainage system installation (gutters and leaders) resulting in flooding the foundation and water entry passing under the wall bottom and up over the basement slab at the slab/wall joint. Foundation leaks are not a product defect it's a poor installation practice. Some builders look at the pre-cast concrete wall sections as a waterproof material, forgetting that water can enter under a foundation or between improperly sealed foundation sections.
  • Excessive spanning of areas by pre-cast concrete foundation sections with no fill and no footing at all (shown in photo above) may lead to future water entry, floor slab settlement, or in severe cases, foundation movement. Spans over five feet would violate a Superior Walls guideline and other spans may be improper depending on the product and the engineering design for the project.

    Clarification from Superior Walls,
    Builder Guideline Booklet MAN 42-9000(June 2010) page 11 Figure 4 indicates that the maximum allowable over dig for a Superior Walls product is 5’-0”.  Inspectors observing large open spans of foundation walls should refer their clients to the original project engineer and the engineering drawings to check compliance.

    Note:  Superior Walls of America considers quality installations very important to our process, that is why every Superior Walls project is installed by a trained certified installer and Superior Walls panels are not by the builder or general contractor.
  • Basement water entry and leak problems require adaptation of common internal trench and drain systems, as cutting the slab to excavate for an internal drainage trench exposes the gravel footings. Inspectors should look closely at the connections and sealant between wall sections and look for evidence of leakage. While some manufacturers do not require sealing the inside bottom of the footer beam, as we note below, inspectors of existing structures are certainly expected to examine all foundation areas, corners, joints, footings, for indications of a history of water entry.

    Clarification from Superior Walls:
    It is certainly important that the joints are sealed properly to prevent possible water leaks.  However, when sealing Superior Walls panels it is not necessary to seal the inside bottom of the “Footer Beam”.  Therefore, we believe the picture that depicts the sealant not being  applied to the vertical section of the footer beam is not  a good example of “Incomplete Sealing”.

Special basement waterproofing system details are needed if a basement de-watering system is installed after construction of a building with precast concrete foundations or walls. Foundation waterproofing companies such as B-Dri ™ who are asked to address water entry in homes built with these systems have to use modified intercept drain materials because the absence of poured footings under the walls gives less depth for an in-basement trench.

Reputable manufacturers of precast foundation wall products, including Superior Walls of America, supply their customers with site prep and construction details and that these are a great resource for inspectors.  Superior Walls provides these details in Builder Guideline Booklet MAN 42-9000 [local copy] which is available on-line, free of charge.  This booklet includes a series of checklists, including one for Code Inspectors.


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