Cypress Knees Under a House: Removal and Management

What Are Cypress Knees?

Knees are woody root projections that emerge above waterlogged soil, primarily on bald cypress (Taxodium distichum). They function in gas exchange but their exact role is debated. Size correlates with water level—typically 5–12 inches, up to 36 inches in constantly flooded conditions.

Management Options

If Keeping the Tree

• Cut knees at ground level—does not harm the tree.
• Repeat every few years as new knees emerge.
• No chemical treatment needed or effective.

If Removing the Tree

• Cut knees and immediately paint fresh cuts with undiluted Roundup (glyphosate) using a brush.
• Herbicide translocates to main roots and trunk, killing the entire tree.
• Dispose of brush after use.

Important Notes

• Knees only form in prolonged saturated/wet conditions.
• Removal has no proven negative effect on tree health.
• New knees will appear in other locations over time—monitor periodically.

For structural protection under a house, regular cutting at ground level is the only practical long-term solution if the tree stays.