I have no gutters on my house and my foundation-level garden beds are washed away with each heavy rainstorm. I am considering placing large-sized gravel under the roof line to deflect the splashing runoff. Do you have any other suggestions?
Mary Boyle, Piscataway, NJ
Todd Phillippi, an architect and landscape designer in Langhorne, Pennsylvania, replies: Rather than just placing a layer of gravel under the roof line to deflect the runoff rainwater, establish a series of channels and paths to direct runoff away from the house.
First, dig shallow channels next to the foundation wall that are centered beneath the roof eaves. Then lay a double layer of 6 mil PVC plastic sheeting into each channel right up to the foundation wall. Cover the plastic with a few inches of smooth, decorative gravel. If angular stone is desired for appearance purposes, use a heavier plastic sheet.
These channels should gently slope away from the house into paths located at least 8 feet away from the foundation. Any rainwater collected in the channels will then run into a path and away from the house.
Historically, it was common to dig shallow trenches at the foundation levels of buildings to collect and direct rainwater away. Usually lined with brick and shaped like a gully, this collection system needed to be durable enough to withstand the concentrated force of water falling from a roofline that was one, two, or maybe three stories high. This age-old approach to drainage can be seen in colonial-era Williamsburg, and is still used to some extent today.
When camouflaging this drainage treatment with garden plantings, try to use shrubs that won’t be severely damaged by sheets of water and piles of snow. Also, a metal diverter angle can be installed on the roof in line with the front door entrance to keep the entryway clear of drips.