How Do You Grade for Foundation Drainage?
The ground should drop at least 6 inches over the first 10 feet away from the foundation — roughly a 5 percent slope, and the minimum the residential code requires. Grading is the first and most cost-effective defense against foundation moisture: correcting a negative grade with compacted topsoil runs $500 to $5,000 professionally, or $100 to $300 in materials as a DIY job. Here is how to assess and improve your home’s drainage grade.
The Standard: 6 Inches in 10 Feet
The International Residential Code (IRC Section R401.3) requires that the final grade within 10 feet of the foundation slope away from the structure at a minimum 6-inch drop over 10 feet (roughly a 5 percent slope). This slope ensures rain water flows away from the foundation rather than toward it. In practice: many homes have slopes that have reversed over time as soil settles away from the foundation wall. Assessing your current grade: place a 10-foot board with a level against the foundation wall and measure the elevation difference between the foundation end and the outer end — the outer end should be at least 6 inches lower than the foundation end.
Correcting Negative Grade
When the grade slopes toward the foundation (negative grade): add clean topsoil or crushed stone along the foundation perimeter and compact it to create positive slope. Materials: bagged topsoil ($5 to $10 per 40-lb bag, covering approximately 2 sq ft at 1-inch depth), or bulk delivery from a landscape supplier ($25 to $45 per cubic yard, covering approximately 50 sq ft at 2-inch depth). The new soil must be compacted — uncompacted loose soil will settle and the negative grade will return within 1 to 2 seasons. Compact with a hand tamper or a plate compactor. Grade correction for a typical home’s foundation perimeter: $500 to $5,000 professionally, or $100 to $300 in materials for a DIY correction. This is typically the most cost-effective foundation drainage improvement available.
What Not to Do
Do not add organic material (mulch, compost) against the foundation wall as a grade correction. Organic material holds moisture rather than draining it, provides habitat for termites and wood-boring insects, and can direct moisture into any foundation cracks. The correct material for the area adjacent to the foundation: clean topsoil (for lawn areas) or inorganic crushed stone or gravel (for a planting bed border). Keep all organic mulch and landscape material at least 6 inches away from the foundation wall surface.
Working With a Contractor on This Project
Getting the right outcome on any home services project starts before the work begins. A few consistent practices make the difference between a smooth project and a frustrating one.
Get at least two or three quotes. A single quote gives you no basis for comparison. Two or three quotes reveal the market rate for the work, expose scope differences between bidders, and let you assess contractor communication quality before any commitment is made. The lowest bid is not automatically the best value if the scope is thin or the materials are underspecified.
Ask for licenses and insurance before work starts. Verify current general liability insurance and, for any work involving workers on your property, workers compensation coverage. Licensing requirements vary by state and trade; confirm the specific requirements in your jurisdiction. A licensed contractor who carries appropriate insurance protects both parties if something goes wrong during the project. (For more on this, see Questions to Ask Before Installing a Foundation Drainage System.)
Get the scope in writing. A written proposal that specifies materials, labor scope, timeline, what is included (permits, cleanup, disposal), and warranty terms is the foundation of a professional engagement. Verbal agreements on any of these points invite misunderstanding. For any project over $500, written scope is non-negotiable.
Clarify the payment schedule upfront. A reasonable payment schedule ties major payments to project milestones: a deposit at signing, a payment at material delivery or project start, and a final payment at completion after a walkthrough confirms satisfaction. A contractor who requires full payment upfront before work begins is a red flag in any trade.
Making a Confident Decision
The information in this article is designed to help you ask better questions of the professionals you work with, evaluate their answers with more confidence, and understand the decisions involved in this type of home services project. It is not a substitute for professional assessment of your specific home.
Every home is different. Roof slopes, local weather, tree exposure, soil conditions, and existing system condition all affect what the right solution is for your specific situation. The general principles here apply broadly, but a professional who assesses your home in person will give you guidance that accounts for the details that general articles cannot.
When you are ready to move forward, getting at least two or three quotes from licensed, insured, local contractors is the most important practical step. It lets you compare approaches, assess contractor quality, and confirm that the solution proposed matches your specific situation and budget.
Cost figures on this page were checked against published pricing on September 2, 2026. How we source cost data.
