Improper Ground Cover Placement and Maintenance Errors Offer Expensive Landscaping Lessons

by John H. zumBrunnen, Founder, zumBrunnen, Inc.

Sometimes, seemingly small errors result in problems that are surprisingly expensive to correct. From our work in conducting thousands of property condition assessments, one of the most common, yet easily-fixed, problems we see is the improper placement of ground covers such as pine straw and mulch.

Pine straw and mulch are used as ground cover around the perimeter of both residential homes and commercial buildings for three main reasons: they are an attractive enhancement to the landscape package, do not require mowing, and most importantly, help retain ground moisture.

As pine straw and mulch help retain moisture, they will create a moisture problem in the building wall when in contact with the buildings’ exterior finish  systems such as brick, stucco, stone, cultured stone, exterior insulation finish systems (EIFS) or siding. Excessive moisture will damage the building wall system causing wood decay, which can lead to structural damage; damage to sheathing, sheet rock and other finishes; promote the growth of mold and mildew; and cause loss of insulation ratings. Significant damage typically occurs well before the problem becomes visible on the interior of the building.

Furthermore, moisture attracts insects, including ants, roaches and termites. These conditions create a pest maintenance issue and damage, and will void pest control and damage warranties.

We often see pine straw and mulch in contact with HVAC pad-mounted air-conditioning compressors (AC).  Contact with the AC unit metal base and frame and fin tube coils results in additional moisture in and around the unit.  This condition will collect dirt, attract insects, promote mold, damage controls, and cause metal components to rust prematurely, thereby reducing operating efficiencies and shortening life and possibly voiding warranties.

Prevent Ground Cover Nightmares with the “6-Inch Rule”

Always keep pine straw, mulch, or other ground cover a minimum of 4-6 inches away from the base of siding, brick, stucco and other exterior finish materials, unless special design accommodations for soil or ground cover contact are implemented.  For example, when materials such as brick must continue below grade (grade refers to the ground level at the outside walls of a building), the brick system will require a flashing just above finish grade (the top surface of lawn, sidewalk, etc.) and ground covers to isolate the below grade brick from the above grade and ensure that the weep holes (small openings in a wall through which water may drain to the exterior) are maintained above grade and ground covers.  The flashing is a thin waterproof material that prevents moisture from migrating up into a wall cavity and allows for proper drainage and ventilation through the weep holes.

Universal building codes require finish systems terminate at 6” above grade to accommodate for ground covers to mitigate moisture issues.   The same applies to the finish elevation for a slab-on-grade.  While code requires a 6” clearance, oftentimes this requirement is violated during original construction and too, over time, soil amendments and landscaping practices can build up a higher base.

To prevent potential problems, it is imperative to remove excess ground cover and if necessary to regrade the soil so that water properly drains away from the building perimeter. However, be cautious about creating a dam around the building that would channel water back.  In such cases where grades cannot be lowered, a French drain system will prove to be a part of the solution.  A French drain consists of a trench filled with loose stones and covered with earth.

We encourage homeowners and commercial building owners to conduct a perimeter check twice a year.  If an outside contractor maintains the grounds, we suggest the owner add language into the landscape service agreement stipulating the provider will “maintain a minimum 6-inch contact clearance around the perimeter of the building and not allow contact with HVAC equipment to prevent problems, or be liable for correcting the damage.”

About the Author:

John zumBrunnen is founder of zumBrunnen, Inc., an independent construction and building consulting firm founded in 1989 with offices in Atlanta, GA and Charlotte, NC. zumBrunnen has a BS in mechanical engineering from the University of North Dakota and completed the US Army Corps of Engineers Training Program in 1972. zumBrunnen is involved with LeadingAge (and various state chapters of the organization). His company is also a member of the Georgia, North Carolina and South Carolina Chapters of the Community Associations Institute (CAI). zumBrunnen has been a faculty member since 2003 for the University of North Texas, Coalition for Leadership in Aging Services (CLAS), a national certification program for aging services professionals (CASP), and authored their “Asset Management” training module. zumBrunnen has 40+ years’ experience in construction, property assessment, development, and reserve budgeting. He is the inventor of the FacilityForecast® software system and a respected industry author and speaker.

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