Thanks to Grant Kirker for writing this article spotlighting how homeowner’s can better maintain their wood decks. Kirker is a Research Forest Products Technologist at FPL in the Durability and Wood Protection Research unit.
Benjamin Franklin is credited with the saying “an ounce of prevention is worth a pound of cure”, which suggests that taking steps to avert a problem before it starts is far better than taking corrective steps after the problem arises. Forest Products Laboratory (FPL) Wood Durability and Protection researchers, in collaboration with research partners at Oregon State University, attempted to apply this concept to a situation close to home for many homeowners—the wooden deck.
The global wooden decking market in 2020 was valued at $15 billion USD, of which the North American markets made up about 35%, or $5.25 billion USD1. In a 2019 National Association of Homebuilders (NAHB) survey2, 20.3% of all new houses included decks. Although this estimate is lower than historical averages, the global pandemic has led to an increasing interest in outdoor living spaces, which will likely cause this market to increase. Wood is an excellent building material for outdoor decking because of its reasonable cost and low maintenance requirements; if properly installed and maintained, a wood deck can provide a long-lasting benefit to the homeowner.
However, some periodic maintenance is an important component of owning a wood deck. Over time, organic detritus, most commonly leaf litter, accumulates and settles into cracks and crevices and can cause situations that closely resemble ground contact due to excess moisture, nutrients, and fungal material. This research, published in the journal Microorganisms, examined the role of accumulated leaf litter on material performance and wood durability in aboveground exposure.
Simulated deck microcosms were constructed to mimic worst-case situations for wood rot in aboveground exposure and were installed outdoors at two locations in South central Wisconsin. Untreated pine was exposed to both fresh and aged leaf litter to determine if decay capacity of leaf litter increases as it ages. Moisture readings of the wood were collected over time along with visual decay ratings at 4, 13, 24, and 41 months. Wood sawdust and leaf litter samples were taken at 25 and 41 months of exposure, and DNA was extracted and analyzed using amplicon-based sequencing to identify fungal inhabitants.
Results showed that moisture and resultant decay were accelerated in the presence of leaf litter and that onset of wood decay happened most rapidly where aged leaf litter was present. Analysis of the fungal sequencing data showed that leaf litter contains a significant number of fungal species that are available to inhabit and decay the wood and that the species composition shifts over time to include more basidiomycete fungi, which are primarily responsible for wood decay.
Some overlap was seen between those species found in the leaf litter and wood, but wood with leaf litter absent showed dissimilar fungal communities. These results highlight the importance of incorporating a maintenance schedule that minimizes accumulation of leaf litter to prolong the service life of the wood. The published results from this study are for untreated wood only, but analyses of samples from preservative-treated wood are currently underway.
An ounce of prevention goes a long way for wood to have a more robust service life. For more on leaf litter and its role in wood decay, read the entire journal article: “Role of Leaf Litter in Above-Ground Wood Decay.”
Contact us about this research or any of our other incredible projects at https://www.fpl.fs.fed.us/news/mediacontacts/index.php
To find out more about the extraordinary contributions our researchers are making to the world of wood science, please visit the Forest Products Laboratory at https://www.fpl.fs.fed.us/