IIBEC’s Technical Advisory Committee Encourages Members’ Input And How to Remove Moss From Shingles

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April 16, 2020
By Walt Rossiter

Since its beginnings, the tasks assigned to the IIBEC Technical Advisory Committee (TAC) have focused on two important activities:

  • Identifying technical issues facing the building enclosure community that are of concern to the IIBEC membership, and
  • Developing IIBEC Technical Advisories (TAs) or Position Statements (PSs) that define these issues and provide recommendations to avoid or mitigate them in practice. The IIBEC Board of Directors approves all TAs and PSs before they are released on the association’s website.

At present, IIBEC has issued 19 TAs, with the most recent issued in March as TA-019, titled “Modified-Bitumen Cool Roof Cap Sheets.” TA-020, titled “Roof Covering Systems and New Concrete Roof Decks,” is under development and expected to be available within the coming months. All TAs can be accessed at https://iibec.org/advocacy/technical-advisories/.

The issuance of a TA is the final step in a rather lengthy process. Significant time often elapses as a number of drafts are developed and debated before the TAC approves sending a draft to the board for approval to be released. To initiate the process, the TAC members need to identify and accept topics considered to be worthy candidates for taking an official position or making a recommendation to IIBEC membership via a TA or PS. This is a critical step, not only because TAC members are volunteers and their available time is limited, but also because all topics need to have substantial attraction to the broad spectrum of interests of IIBEC members. Consequently, all topics that come to the TAC’s attention are taken into consideration, but not all are accepted.

There are three main ways of identifying TA topics:

  1. TAC members recognize pending technical issues based on projects that they undertake in their own practices.
  2. The IIBEC Board of Directors requests that a topic be examined.
  3. IIBEC members bring issues to the TAC’s attention, generally in response to the TAC’s periodic placement of a note in IIBEC’s online newsletter, which we call the Newsfeed. Such notes request that IIBEC members inform the TAC of technical issues they have encountered in practice.

This third means is as important as the first two, and is the impetus for this note. If you experience an issue that might be of broad technical concern to the building enclosure community, please inform the TAC. You can do this by writing to TAC Chair Doug Stieve at dstieve@wje.com, or me at wjrossiter@verizon.net. If you send a concern, discussion of its appropriateness will be on the agenda of the next TAC meeting. Based upon the discussion, you may be asked for further information supporting why you consider that the topic raised should be examined by the TAC.


“Moss Covered Roof” by ArtTower on Pixabay

Request Leads to Information About Moss Removal From Shingles

A few months ago, an IIBEC member noted, “We have encountered, along with some of the shingle suppliers that we spec, an issue when demossing asphalt shingles.” The note explained that the issue appeared to be associated with washing the surface of shingles with detergents, and asked that the TAC look into the question.

The proposed issue was of interest to the TAC. The members seriously debated taking on the topic, but in the end, decided that a TA was not needed. It was not that the issue was unimportant. On the contrary, they concluded that the issue belonged in the domain of the Asphalt Roofing Manufacturers Association (ARMA). This position was influenced greatly by ARMA’s already having published a brochure titled “Algae and Moss Prevention and Cleaning for Asphalt Roofing Systems.” So in lieu of developing a TA, the TAC asked that I write a short comment for the Newsfeed to remind IIBEC members of the existence of this ARMA brochure. It is freely available and may be accessed at: http://facilitiesnet.com/emails/Custom/051412_ARMA/default.asp.

The brochure is comprehensive, addressing a number of topics in a succinct package that should be of interest to IIBEC members whose practices include asphalt shingle roofing. Examples include:

  • Background information on algae and moss buildup on asphalt shingles
  • The most effective method of cleaning the algae and moss
  • Other preventive measures, such as zinc and copper strips, and when to use them
  • The consequences of algae and moss buildup
  • Steps for discouraging algae and moss growth

Because the question from the IIBEC member focused on cleaning asphalt shingles, I have included a paragraph from the ARMA brochure that it describes as the “most effective method,” below:

The most effective method of cleaning algae and moss from a roof is with a 50:50 mix of laundry-strength liquid chlorine bleach and water. Apply with a sprayer and allow the solution to dwell on the roof surface for 15 to 20 minutes, and then rinse thoroughly with low pressure water. Extended dwell times may be necessary; however, avoid letting the solution dry completely as this may prevent complete rinsing. Take proper precautions to protect landscaping and surrounding areas from the chlorine bleach solution. Use appropriate personal protective equipment when working with chlorine bleach. Algae will disappear and wash away with subsequent rains. Moss will loosen over time and may be removed with a leaf blower. In severe cases, it may take more than one bleach treatment to kill all of the moss. Never use a pressure washer to clean an asphalt shingle roof as this will cause granule loss and very likely premature failure of the roof system.