Rules of thumb used for exterior grading and tree and vegetation proximity around a home’s foundation are intended to prevent water and excess moisture from entering the housing space and damaging the foundation or clogging drain piping.
Building materials are porous and can absorb water through capillary action. Foundations containing concrete, wood, brick, stone, and mortar can come into contact with soil and can literally suck water and transport it through building materials. To provide adequate drainage away from the house, the recommended slope for exterior grading is 5%, or roughly 6 inches for the first 10 feet from the house. The EPA also recommends that exterior slabs such as patios, walks, and driveways should have a minimum slope of 1/4 inch per foot with adequate backfill to avoid settling.
In addition, trees and vegetation planted close to the home, such as hardwoods (broad-leafed deciduous trees) and softwoods (connifers with needle-leaves, evergreens), can be a cause for home settlement due to soil shrinkage (from transpiration), creating the loss of moisture to nearby trees and large plants. Generally, large trees between 25 and 50 feet tall should be a minimum of 15 to 20 feet away from your house. Above a height of 25 feet, trees should be at least 10 feet away from the home. Another rule of thumb is that a tree’s proximity to a house should be at least one-half of its maximum tree height. Shrubs and large bushes should be planted a minimum of 6 inches away from the house, but 12 inches is preferred.
Trees with the least invasive roots include Japanese maple, Kousa dogwood, crape myrtle, and eastern redbud. For small yards, good choices that avoid potentially damaging root spreadage are: Royal Star magnolia, Prairifire crabapple, Camellia japonica, and Black Diamond crape myrtle.
Recent Comments