What are signs of good building site drainage?

Assessing Site Topography

When evaluating a building site’s drainage, it’s essential to assess the topography. A site with a gentle slope of 1-2% (1-2 feet of fall per 100 feet of horizontal distance) is ideal. This allows for easy water flow away from the building without creating erosion issues. To determine the site’s slope, use a transit or a smartphone app that utilizes augmented reality to measure distances and angles.

Identifying Water Flow Paths

Once the site’s topography is understood, identify the natural water flow paths. These are areas where water tends to collect and flow, often along natural ridges or swales. The goal is to direct water flow away from the building by creating a swale or a shallow ditch that captures and redirects water. A typical swale is 2-3 feet deep and 4-6 feet wide, with a gentle slope of 1-2% to ensure water flows freely.

Creating a Drainage Plan

To create an effective drainage plan, consider the following techniques:

• Install a French drain: a trench filled with gravel and a perforated pipe that directs water away from the building.
• Use a rain garden: a shallow depression that captures and filters rainwater, allowing it to infiltrate the soil.
• Implement a gutter system: a network of gutters and downspouts that direct water away from the building and its foundation. By incorporating these techniques, you can ensure a well-drained building site that protects your off-grid cabin from water damage and erosion.