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The most comprehensive review by independent engineers of the current state of the practice related to the protection of plumbing from expansive soils under foundations was presented at the Building Professional Institute ( by 3 engineers (1 geotechnical, 1 mechanical and 1 structural) with each one having over 40 years of experience with expansive soils in their respective disciplines.  Below are the slides from their 3 hour presentation.  In their presentation, they refer to major litigation arising from failures of non-isolated plumbing under isolated slabs and the recommend Mechanical Engineers “immediately cease and desist the practice of permitting Non-Isolated Plumbing (Buried Plumbing or Non-Isolated Void Systems) under Slab-On-Voidwork foundations…”.  


A review of the above Building Professional Institute presentation was presented by another set of 3 engineers (another 1 geotechnical, 1 mechanical and 1 structural) from 3 different engineering firms to the Dallas Chapter of the Structural Engineers Association of Texas in November 2022.  All 3 of the SEAoT Dallas presenters stated, "All 3 presenters of this SEAoT Dallas presentation today agree with the content and recommendations presented at the North Texas BPI Presentation by those 3 engineers."  Below is the SEAoT Dallas presentation.


Current codes require protection of plumbing from expansive soil under foundations.

Under isolated slabs, plumbing is effectively protected only if the plumbing is isolated.

The Mudskipper System is the most cost effective way to isolate plumbing.

No other products isolate plumbing under slabs poured on carton void forms.

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