Last week I posted an update on Diamond Pier footings, and since then I've had a number of people ask me whether or not Diamond Pier footings are approved for use in this city or that city. The best way to get the most accurate, up-to-date answer to that question is to contact the building inspections department for the specific city and ask.
Why can't this information be quickly looked up? Because the Minnesota State Building Code does not specifically allow the use of Diamond Pier footings. There are a bazillion products that the building code doesn't specifically allow. That doesn't mean they can't be used, but the building official needs to give permission to use them. That's why plans need to be submitted to the building official before work is started. Section 1300.0110, Subpart 13 of the Minnesota State Building Code says:
Subp. 13. Alternative materials, design, and methods of construction and equipment.
The code is not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by the code, provided that any alternative has been approved. An alternative material, design, or method of construction shall be approved where the building official finds that the proposed design is satisfactory and complies with the intent of the code, and that the material, method, or work offered is, for the purpose intended, at least the equivalent of that prescribed in the code in quality, strength, effectiveness, fire resistance, durability, and safety. The details of any action granting approval of an alternate shall be recorded and entered in the files of the Department of Building Safety.
So, do Diamond Pier footings comply with the intent of the code? Are they at least the equivalent of that prescribed by the code in quality, strength, effectiveness, etc? For a manufacturer to prove that their product meets the intent of the building code, they get an ICC-ES report. It's a report designed for building code officials to use to help determine if a product meets code, and it tell the building code official exactly how a product is supposed to be installed. In fact, the instructions in the ICC-ES report actually supersede the manufacturer's installation instructions. If you're building a deck, a few components on the deck that may need an ICC-ES report are the composite deck boards, the aluminum guardrails, the structural wood screws used to fasten the ledgerboard to the house, the joist hangers, and the lateral load connectors. Diamond Pier footings have an ICC-ES report too, which can be viewed here: ESR-1895.
As long as the building official determines that Diamond Piers meet the intent of the code, they shall approve their use. So, gettting back to the question at hand: are Diamond Pier footings allowed for decks in <insert city>? I called the building inspections departments at the twenty largest cities in Minnesota to find out. Here's what they said:
|Duluth||no, because "they have not been state approved".|
|Eden Prairie||yes, need to use DP75 footings|
|Golden Valley*||yes… but they require a test hole to be dug first, as well as a site inspection.|
|Rochester||yes, case by case basis|
|St. Louis Park||no|
|*||Not one of the 20 largest cities, but included in this list anyways.|
So there you have it. Of course, by the time you read this, the answers might change. If you have any specific questions about the answers given, contact the building inspections department at that city.
For more information on code approval of Diamond Pier footings in Minnesota, check out Diamond Pier's discussion of this topic on their web site: Code Compliance Information for Diamond Pier® Foundations in the State of Minnesota.