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Minnesota Department of Labor and Industry

Opinion: Headlok Foundation System




Headlok Foundation System

Code Reference:

2007 MSBC

Submitted by:

Anchor Block Company

Prepared by:

Structural Technical Opinion Committee

Approved by:

Thomas Anderson, State Building Official

Issue Date:

July 30, 2007


Anchor Block Company is seeking an opinion letter from CCLD regarding code compliance of a newly developed open-cell masonry product/system titled Anchor Headlok Foundation System.


It is the opinion of CCLD that Headlok System, manufactured by Anchor Block Company used for frost footing applications with no differential fill, meets the intent of the 2007 Minnesota State Building Code.

Conditions for use:


Frost-protected foundation wall that is supported continuously by a concrete footing.


Equal backfill conditions


Installation in accordance with the manufacturer's details and requirements.


Shall be capable of accommodating all loads according to 2006 IRC Chapter 3 or 2006 IBC Chapter 16 and transmitting the loads to the supporting soil.


Headlok units meet or exceed ASTM C90.

Background information:

First it needs to be clarified that this division has no authority to approve or certify products as complying with the building code. This is the sole responsibility of the local building official. However, we can certainly review products or methods of construction and offer an opinion as to compliance.

Anchor Block Company has developed a concrete masonry foundation system called Headlok. It is intended for use in Minnesota as a load- bearing, frost-protected foundation wall that is supported by concrete strip footings constructed below the frost line. The Headlok Foundation System incorporates a mechanical tongue and grove interlock configuration at the vertical head joints in lieu of conventionally mortared head joints.

Anchor Block Company retained the services of American Engineering and Testing (ATE) where a generic Headlok foundation wall section was constructed, tested and analyzed for structural integrity and performance. The test results exceeded the test results of a wall section built with conventional concrete masonry units and mortared head joints. Anchor Block Company also has unit testing data which demonstrates the product meets or exceeds ASTM C-90 requirements. Anchor Block Company has provided CCLD a binder for the Headlok Foundation System that details "typical" construction details and requirements as well as ATE's product descriptions, testing data, design and section descriptions.

Anchor Block Company has been selling the Headlok Foundation System in Minnesota for nearly two years by gaining alternate foundation system approvals from some local building officials. Alternate approval requests were necessary because the masonry units Headlok Foundation System are constructed with one open end, the head joint is not mortared, and the head joint is constructed as a mortarless tongue and groove assembly. This mortarless tongue and groove assembly is a direct departure from the 2007 State Building Code in the design, construction, and installation of open cell masonry units.

Mark Joslyn has submitted Anchor Block Company's request for the CCLD's opinion. Mark can be reached at:

Mark Joslyn
Anchor Block Company
2300 McKnight Rd.
North St. Paul, Minnesota 55109
Cell phone (612) 369-2003

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