A foundation line that falls too close to the soil grade can increase the risk of basement leakage and creeping damp.

In response to a reader’s question, AskABuilder columnist Tim Carter talks about the dangers of low foundation height, and the methods a builder can use to make their high foundation property appear level.

He uses the construction methods of “houses that were built in the late 1800s or early 1900s” as an example, in which foundations rose 30 inches above the grade and included wood-frame windows at least six inches above soil level. Not only did this allow natural light into basement spaces, but the window height was sufficient to keep out splashing water and creeping damp.

According to Carter, building codes from “not too long ago” require a minimum of least six inches of foundation showing above the soil grade, and at least six inches of fall in the soil in the first ten feet away from the house. Carter recommends building a foundation at least 18 inches higher than the surrounding soil, and using dirt dug from the basement to make a “long gentle slope” away from the foundation.

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