case study-removing mold from duradek · 2016-11-15 · house siding, cars, plants, or other...

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Case Study: Diagnosing & Removing Mold from Duradek

Private Residence Fairfax Station, VA In 2009, a family in Fairfax Station, VA had a large addition built on the rear of their home by Sun Design and Remodeling. Part of the design called for Duradek on a 9’x9’ deck over a screened porch. Duradek Ultra Marble Mocha was installed by Duradek of Virginia in November 2009.

Written by: Jaime Kotanko Duradek MidAtlantic April 2013

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Within a year of installation, the home-owners started noticing a lot of dirt and black spots on the Duradek surface. The homeowner was advised to clean the Duradek with Duradek Deck Cleaner. The spots were removed, but with great difficulty and effort (scrubbing on hands and knees for over 6 hours to clean the entire deck). Further, the spots returned within a month or so.



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As a result, Duradek MidAtlantic made the first site visit in May of 2012 to begin inves-tigating what the spots were and the best way to treat them. Unfortunately, the deck had been freshly cleaned at that time and we weren’t able to observe the spots, but were able to observe the surrounding area. We noted that the deck was directly adja-cent to a densely wooded area with many tree branches nearly reaching over the deck. The trees included several oak spe-cies, chestnut, and tulip poplar. We also noted a lot of potted plants on the deck as well as areas landscaped with mulch be-low. We noted many dark, raised spots on the trim and composite deck below the Durad-ek. Upon further research, we determined these spots to be artillery fungus spores.



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Artillery Fungus description from Penn State Col-lege of Agricultural Sciences: They are in the genus Sphaerobolus. These fungi colonize on dung or other organic matter such as wood mulch. The artillery fungi grow on organic matter and create dark brown spore packets, called peridioles, that sit on top of specialized cup-shaped cells. When the cells accumulate enough liquid, the cupped cells invert causing the cells to burst and propel the peridoles up to 6 me-ters high where they adhere to surfaces such as house siding, cars, plants, or other structures.

Based on our research, we thought that this may be the answer. However, after consulting the USA’s leading expert on artillery fungus, Dr. Don-ald Davis of Penn State University, we decided this was not the likely cause. Dr. Davis explained that there would have to be an extraordinarily large amount of artillery fungus in a limited area to pro-duce the number and frequency of spots observed on this deck. Further, Dr. Davis explained that he had never seen the spots ‘melt’ and spread out as seen on this deck. He explained that the spore that is shot out remains a hard raised bump about the size of a pencil tip. We inquired as to whether the plasticizers in the vinyl would cause the spores to ‘melt’ and Dr. Davis said he didn’t believe that was possible. The pictures shown on this page are provided by Penn State College of Agricultural Sciences.

Dr. Davis pointed us in the direction of investigat-ing sooty mold as he believes that was what is shown in the pictures. Further information on artillery fungus can be fount by following this link: http://pubs.cas.psu.edu/freepubs/pdfs/ul201.pdf



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Case Study:

Removing Mold from Duradek The final diagnosis came as a result of researching Dr. Davis’s suggestion of sooty mold. Sooty mold description from the US Department of Agriculture Forest Service: Sooty molds are dark fungi that grow on honeydew excreted by sucking insects or on exudates from leaves of certain plants. Typically, sooty mold growths are composed of fungal complexes made up of asco-mycetes and fungi imperfecti. Some of the common genera of fungi found in sooty mold complexes are Cladosporium, Aureobasidium, Antennariella, Lim-acinula, Scorias, and Capnodium.

The dark color of sooty mold growth is due to the presence of melanoid pigments in the cell walls of the hyphae that make up the sooty mold colonies (fig. 1). Many sooty mold fungi have mucilaginous cell walls that help them adhere to the surfaces on which they grow and also serve to prolong periods of wetness by absorbing moisture for their growth.

The pictures shown on this page are provided by the US Department of Agriculture Forest Service.



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Case Study:

Removing Mold from Duradek Once we felt comfortable with the diagnosis of sooty mold, we had to determine the source and how to get rid of it. According to the US Department of Agricul-ture Forest Service: Honeydew excreted by sucking insects such as scales and aphids (fig. 2) serves as a balanced growth medium for fungi. Insect honeydews contain sugars, amino acids, proteins, minerals, and vitamins. All are re-quired for fungus growth. Sooty molds can also grow on exudates produced by glandu-lar trichomes on leaves of some plants such as Catalpa, Hibiscus, and Juglans species.

According to the Morris Arboretum of the University of Pennsylvania’s Plant Clinic a wide variety of trees and shrubs are suscep-tible to aphid infestation. However, the tulip poplar is very susceptible in this region.

One of the largest trees overhanging the deck is a tulip poplar. Further, the same spots were observed on two other decks re-cently (one in Annapolis, MD and one in Worton, MD) both of which had large tulip poplars in close proximity. The owners of these decks described cleaning issues simi-lar to this homeowners’.

Based this information the issue was diag-nosed as sooty mold growing on honeydew from aphids infesting surrounding plants (especially tulip poplar trees).


Annapolis, MD

Worton, MD


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Case Study:

Removing Mold from Duradek The solution to this issue is two fold: the source of the honeydew must be eliminated and the existing sooty mold completely killed and removed from the Duradek sur-face.

The homeowners contacted an exterminator and had their tulip poplar treated for aphid infestation. They will continue to have to treat the tree on an annual basis.

As for cleaning the deck, Duradek Deck Cleaner only removes the surface mold but does not completely kill the colony or re-move all of the honeydew allowing the spots to come back very soon after cleaning.

After contacting Clorox, we decided to pro-ceed cleaning the deck with a diluted bleach solution. Using Clorox Outdoor Bleach (concentrated), we mixed a solution accord-ing to the directions for cleaning vinyl sur-face at a rate of 6 parts water to 1 part bleach.

The bleach solution was applied to the deck surface using a garden sprayer and allowed to sit on the surface for a minimum of 10 minutes. The solution was re-applied to ar-eas that began to dry during this period.

A soft bristle brush on a stick was used from a standing position over the entire surface. Small spots that remained were addressed with a firmer bristle brush from a standing position. The entire area was then rinsed very thoroughly with a garden hose.

The entire process took less than 45 minutes and the deck looked brand new. This is a much easier method than previous-ly described involving hand scrubbing for several hours.


Before

After


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Case Study:

Removing Mold from Duradek As a final experiment, we want to determine how the homeowner’s deck appearance and cleanability would be affected by sealing and painting it. We wrapped a piece of 3/4” ply-wood completely in Ultra Heritage Sienna. Half of the sample board was sealed with Zinsser BIN and painted with 2 coats of Valspar Porch & Patio paint.

We intend on following up with the homeowner monthly to see how long it takes the spots to come back after the bleach cleaning method versus the prior methods. We will also com-pare the Ultra Marble Mocha on the deck to the Ultra Heritage Sienna and the painted surface as a way to determine the best surface for a deck in this situation.

Our hypothesis is that it will take longer for the spots to return as the colonies of sooty mold should have been completely killed with the bleach. We further hypothesize that the spots may be easier to clean from a sealed and paint-ed surface due to the isolation of the plasticiz-ers. Time will tell whether these hypotheses are correct.


Before

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case study-removing mold from duradek · 2016-11-15 · house siding, cars, plants, or other...

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