By Kevin McAlister and Rachel Schmidt, Higgins & Associates
For any homeowner, the prospect of a flood is a daunting one. With Colorado seeing over five inches of rain in both May and June of this year, breaking a hundred-year record, the likelihood of experiencing a flood has been significantly higher than in a ‘normal’ year. While a flood can be equally as devastating as a housefire, flood mitigation precautions are often overlooked due to the arid environment in which we live. While installing smoke alarms and removing potential fuel sources such as pine needles and leaves are fire mitigation measures routinely undertaken by HOAs, there are some equally simple mitigation measures than can be taken to significantly reduce the likelihood of a water intrusion event.
The principal goal of any flood mitigation activity is to direct water away from structures. This is often easier to achieve in single family communities where buildings are further apart than in multi-family communities where the proximity of buildings creates greater challenges to managing water flow. The second objective of flood mitigation is to prevent water from entering a structure if it does get to the property façade. However, as the adage goes, “an ounce of prevention is worth a pound of cure” so keeping water away from structures in the beginning is far more effective than trying to keep it out once it gets there.
Gutters are used to capture the discharge from roof surfaces. During heavy rainfall, this can result in a significant demand being placed on these drainage systems. If the gutters are insufficiently sized for the roof area or not periodically cleared of debris, the water can spill over the sides and may no longer be directed as intended. It is especially important not just to clear the gutter paths, but to also ensure the flow continues unobstructed through the downspout.
Downspouts are critical in flood prevention as their job is to collect concentrated water flow and move it away from the building and protects the building’s foundation. As the flow from downspouts is concentrated, it can cause soil erosion at the point of discharge which will ultimately cause more issues. Downspouts need to be extended to discharge at least 5-feet from any foundation. Every foot beyond that provides a bonus level of flood prevention. At the point of discharge, downspout extensions need a splash block, cobbles, or some other means to dissipate the water without causing erosion. Finally, it is good practice to require that landscapers reposition downspout extensions that are often lifted-up during mowing or other landscaping activities.
Window wells are a common feature of Colorado properties with basements and should include a curb or other enclosure to prevent water from flowing into the well openings. Window well enclosures that have sunk below grade or do not form a continuous barrier with the foundation wall should be modified to ensure that water cannot enter the well from the surrounding grade.
Overwatering and Sprinkler Maintenance
With our dry climate, many communities benefit from irrigation systems to sustain plants and lawns. However, overwatering, especially during wet weather, can result in oversaturation of surrounding soils. This can create excessive run-off, erosion issues, elevated water tables, and significant underground hydrostatic pressure on foundation walls, thus increasing the likelihood of basement water intrusion. Be sure to turn off sprinklers during wet weather and conduct regular maintenance on water lines to prevent leaks damaging nearby foundations. Being knowledgeable about landscaping and areas where communities can opt for more water conscious planting and landscaping also helps prevent overwatering.
Maintaining Grading Slope
Maintaining adequate grading slope away from a building is one of the more important counter-flood measures. The International Building Code requires that a minimum 5-percent slope is maintained away from structures for the first 10-feet to ensure that water is discharged away from foundations. Flat ground or ground that slopes towards a building is one of the most common issues we encounter at buildings with persistent water intrusion issues. Site regrading and ensuring there is an uninterrupted route to discharge water off a site or to a suitable outlet point is often the only way to address this issue.
Through regular inspection and maintenance, homeowners’ associations can reduce the incidence of flooding issues and avoid the resultant property damage and distress of a water intrusion event. If in doubt, we advise that a professional architect, engineer, or licensed contractor be consulted prior to undertaking any work to ensure compliance with code and that any future repairs fully resolve any identified deficiencies.
About the Authors:
Kevin McAlister leads the Construction Consulting group at Higgins & Associates. He has over 30 years of experience as both a contractor and a construction consultant addressing issues in the built environment, especially within the tight confines of multi-family communities. Kevin advises HOAs on suitable property rehabilitation and maintenance approaches including drainage, roofing and grading issues and consults on the cost requirements of these activities.
Rachel leads the Civil Engineering department at Higgins & Associates. She has devoted her career to working with homeowners to assist them in assessing and resolving their civil and structural engineering problems. Rachel has helped many HOAs and property managers to manage the process from determining the cause of an issue, to designing, implementing, and validating the repair. She has experience with all property types from single-family homes to extensive multi-family home developments.