The most important consideration is getting the water away from the foundation of the house. To do so, local governmental regulations dictate the height of newly constructed house slabs. Once constructed, you should be able to see approximately 4-6 inches of concrete foundation above the surrounding walks, drives, grass, and flowerbeds. From immediately next to the house the ground should slope gradually away from the house, to eliminate any possibility of standing water next to your foundation.
When houses are first constructed the walks, patios and driveways are usually installed 3-4 inches below the top of the foundation. One of the biggest problems comes from planting beds that have been later added against the foundation. These “foundation plantings” are common and sometimes incorporate raised beds that can elevate the top of the bed near to or even above the elevation of the floor slab.
Planting beds should never be higher than the house slab!
No matter how spectacular the landscape design may be, it is critically important the top of the house slab remain above everything around it. When soil, mulch and planting beds get piled up next to an exterior wall above the house slab, there is an unencumbered path for water and insects to enter your house. Water will pass through brick, stucco, and siding (we have an article on that subject) and can have catastrophic consequences.
So, what happens when your house slab is just barely above the ground around it? There are methods for grading the lawn around the house to get the water moving in the right direction – away from the foundation. A civil engineer or professional landscape company can help with the design and execution of any necessary grading and drainage.
