MEMO

To: Interested parties in the application of MN Uniform Plumbing Code (chapter 11) & 2015 MN Residential Code (Section R405)

From: Mike Hogenson, Standard Water Control

Date: 2017.04.20

RE: Clarification of the MN UPC

This report does not cover all concerns regarding the installation of subsoil drains or interior retrofit drain tile. There are other issues that also need to be addressed such as:

Replacement of the floor with regard to thickness

Contractors that remove the footings to force their systems to fit

Not sealing the concrete joint allowing VOC’s, radon, or other soil moisture into the home

This is only a partial list and most of these concerns can be handled with other codes, for example:

Sealing of a gap in the new Radon Code and Energy Code

OSHA Silica rules

OSHA Asbestos rules

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As you may be aware there is some confusion around how to apply both the new MN Uniform Plumbing Code and MN Residential Code as they relate to subsoil drainage systems. Recently we have encountered code interpretations that lead to more questions than answers. Our intent is to discuss the differences and offer a point of view that serves the codes, code officials, contractors, and — most importantly — the people of Minnesota.

Clearly, codes are essential. They firmly establish minimum requirements that all must meet; protecting the people of the state. However, when the interpretation of two different codes are the source of differing (and sometimes conflicting) compliance requirements, it’s time to take a closer look to see if it can be sorted out.

We are wrestling with two primary questions:

The conflict between the MN Uniform Plumbing Code (MN UPC), chapter 11 Storm Drainage, subdivision 1101.5 Subsoil Drains and 2015 MN Residential Code (MN RC), Section R405.

The question of acceptable drainage pipe alternatives.

We hope to compare and contrast the MN UPC and MN RC with the intention of uncovering a clear path to code compliance. We will also consider ways to ensure alternative drainage systems, in fact, meet code as required by the State of Minnesota.

MN UPC – MN RC DISCUSSION

Until now there has been no clear code to cover retrofit subsoil drains. In the absence of a clear code, many code officials try to apply sections of MN RC to retrofit solutions which is confusing due to language that clearly indicates the MN RC is discussing new construction and exterior drainage as opposed to retrofit and interior drain tile.

SECTION R405 – FOUNDATION DRAINAGE

R405.1 Concrete or masonry foundations

Drains shall be provided around all concrete or masonry foundations that retain earth or enclose habitable or usable spaces located below grade. Drainage tiles, gravel or crushed stone drains, perforated pipe or other approved systems or materials shall be installed at or below the area to be protected and shall discharge by gravity or mechanical means into an approved drainage system. Gravel or crushed stone drains shall extend at least one foot (305 mm) beyond the outside edge of the footing and six inches (152 mm) above the top of the footing and be covered with an approved filter membrane material.

Minnesota Administrative Rules make it clear the MN UPC covers retrofit:

1300.0040 SCOPE.

Subpart 1. Applicability. The code applies to the design, construction, addition, alteration, moving, replacement, demolition, repair, equipment, installation, use and occupancy, location, maintenance, and inspection of any building, structure, or building service equipment in a municipality, except work located primarily in a public way, public utility towers and poles, mechanical equipment not specifically regulated in the code, and hydraulic flood control structures.

Also, MN Administrative Rules state:

4714.0101 CONFORMANCE WITH CODE.

Subp. 3. Existing buildings. In existing buildings and premises in which plumbing systems, drainage systems, or other work regulated by this code are to be added, altered, renovated, or replaced, the new materials and work shall meet the provisions of this code.

A few pages from the Uniform Plumbing Code Illustrated Training Manual have been included in this document and clearly show the UPC covers retrofit drainage systems.

 

DRAINAGE PIPE ALTERNATIVES DISCUSSION

Another question arises when discussing acceptable drainage pipe alternatives for 3” pipe as stipulated by the MN UPC, chapter 11 Storm Drainage, subdivision 1101.5 Subsoil Drains. We understand there is a mechanism that allows a code official to accept an alternative method, but how are the alternative methods vetted? If the alternative method is substandard, fails, and a home is damaged who is liable? Is the contractor on the line, or the code official, or the city?

We’ve talked with some code officials who say, if you can show the system will carry the necessary amount of water they’ll accept it. This raises other questions; who makes the determination of how much water should be moving through the pipe at any given time and are there any other standards that apply?
We tested four different types of drainage conduit currently allowed by some code officials and believe there are 3 standards that apply; size of opening, flow rate, and holding capacity. See our results below.

  • 3 inch Corrugated drainage conduit, has an opening of 7.06 square inches, a flow rate of 35 gallons per minute, and the holding capacity of a one foot section is 1 ¾ liters.
  • 3 inch Rigid PVC drainage conduit, also with an opening of 7.06 square inches, has a flow rate of about 44 gallons per minute, and the holding capacity of a one foot section is 1 ½ liters.
  • The In Slab drainage conduit is a proprietary product and has no published flow rate. It’s opening is approximately 5.25 square inches. Because it sits on a footing, which is supposed to be level, it will have a lower flow rate than either 3 inch corrugated or 3 inch rigid PVC drainage conduit. We were told by one of the conduit manufacturers that drainage conduit installed level has a flow rate of zero. The holding capacity is just over 1 liter.
  • The Multi Flow drainage conduit has a published flow rate of 29 gallons per minute.Each of the 5 pipes has an opening of 1 inch giving the product a total opening of 3.927 square inches. It’s important to note that the flow rate figure is arrived at with the pipe under 10 pounds per square inch of pressure, yet the multi flow pipe is not installed as a pressurized system. This product is also intended to be installed level, in order to have access to the clean outs. Once again, drainage conduit installed level has a flow rate of zero. Holding capacity is ½ liter.

After this testing we sent an email (attached) to Jim Peterson, MN Dept. of Labor & Industry informing him of our findings, in particular, of the product consisting of 5 stacked channels of 1” in diameter tile with a combined area of 3.927 inches squared when 4714.1101.5 requires a drain tile pipe not less than 3” diameter or 7.068 inches squared. His response was interesting:

“I am not familiar with this system or its standards, if any, the installation or performance of such product, but from your description, it would appear not to meet the code. It is something that could be reviewed as an Alternate Material or Method under Minnesota rules, Part 4714.301, section 301.2, or section 301.4 Alternate Engineered Design, providing it is shown to provide an equivalent level of performance and protection.”

Further, based on an attorney’s memorandum, the city inspectors office may be subject to liability issues in some circumstances. Also, when a municipal inspector allows an alternative system that does not meet code, without reviewing technical documentation that evidences equivalency, they may be subject to individual liability.

We believe it’s clear to see the new MN Uniform Plumbing Code covers retrofit, interior drain tile installation and there is no need to refer to the 2015 MN Residential Code and continuing to do so leads to confusion and potential liabilities.

We’ve included a number of documents for reference. Please don’t hesitate to contact me with any questions or thoughts.

Thank you for your time.

 

Mike Hogenson, Standard Water Control