Stair Stringer Layout: The Golden 7/11 Rule Explained

 

### Understanding Stair Stringer Measurements

When it comes to building a safe and comfortable staircase, precision is everything. A minor mistake in your stair stringer layout can lead to a dangerous and uneven set of stairs. To ensure your construction meets standard building codes, especially in the US and Canada, you must understand the core dimensions: Rise, Run, and Throat Depth.

### The Golden 7/11 Rule

As experienced carpenters always say: "Just remember 7/11." This is the golden standard for residential staircases:

* 7-Inch Rise: The vertical height between each step (tread) should ideally be 7 inches. The absolute maximum allowable rise by most codes is 8 inches.

* 11-Inch Run: The horizontal depth of each step where you place your foot should be 11 inches. The minimum standard run is typically 9 or 9.5 inches.

Following the 7/11 rule ensures that the staircase is neither too steep nor too shallow, providing maximum safety and comfort for daily use.

### Minimum Throat Depth Calculation

The throat depth is the uncut solid portion of the lumber left underneath the notches. Maintaining the right throat depth is crucial for the structural integrity of the stairs so they don't crack under heavy weight.

Here is a quick reference guide based on standard lumber sizes:

* For a 9-1/2" stringer, the minimum throat depth must be 3-1/2".

* For an 11-7/8" stringer, the minimum throat depth must be 5-7/8".

* For a 14" stringer, the minimum throat depth must be 8".

* For a 16" stringer, the minimum throat depth must be 10".

Always use a framing square and stair gauges to mark your lumber accurately before making any cuts.