Stairs and Stairwells in NEN 2580stairs

Understanding the Role of Stairs and Stairwells in Measurements

When measuring usable floor area in buildings, stairs and stairwells can present some challenges. Under NEN 2580 guidelines, there are specific rules about how these areas should be measured and categorized. These rules ensure consistent and accurate results across all types of buildings.

In this blog, we’ll focus on the rules for stairs, stairwells, and the space underneath them.

---

1. When Do Stairs and Stairwells Count as Usable Area?

Stairs and stairwells are typically included in the usable floor area if they meet the following conditions:

• Within the 4 m² rule: If the stairwell (including the opening in the floor) is less than 4 m², it is counted as part of the usable floor area.
• Functional purpose: The stairwell must connect areas that are part of the usable floor area, such as living spaces or work areas.

Example:

• A staircase inside a house, leading from the living room to an upstairs bedroom, counts as part of the usable floor area because it connects functional residential spaces.

---

2. The 4 m² Threshold: What It Means

A key factor in measuring stairwells is the 4 m² rule:

• Stairwells smaller than 4 m²: These are included in the usable floor area. Measurement is taken along the edges of the opening in the floor.
• Stairwells larger than 4 m²: The portion of the stairwell exceeding 4 m² is excluded from the usable floor area.

This ensures oversized staircases or large open spaces above stairs (e.g., in atriums) don’t inflate the usable area calculation.

Pro Tip: Always measure along the inner edge of the opening for accuracy.

---

3. Spaces Under the Stairs

The rules for the space under the stairs depend on whether you are measuring a ground-level home (a single-family house) or an apartment. Here’s how they differ:

For Ground-Level Homes (Single-Family Houses):

• All space under the stairs is included as usable floor area, regardless of the height. Even areas with a height below 1.5 meters are counted as part of the usable residential area.

For Apartments:

• The space under the stairs is treated differently if the staircase above belongs to another unit (e.g., the upstairs neighbor’s staircase). In this case, the space under the stairs is seen as similar to a “sloping roof” area:
  • Height < 1.5 meters: This portion is excluded from the usable floor area.
  • Height ≥ 1.5 meters: This portion is included as usable floor area if it is accessible and usable.

Why this difference?

In apartments, the staircase above the storage space is not considered part of the same residential unit. This distinction ensures fair classification between shared and private spaces.

---

4. Shared and Private Staircases in Multi-Unit Buildings

In apartment complexes or multi-unit buildings, stairs are measured differently depending on their location and use:

• Shared staircases: Stairs in common areas, such as those connecting multiple apartments, are not included in the usable floor area of any single unit. They are considered shared space.
• Private staircases: Stairs within a single apartment (e.g., in a duplex) are included in the unit’s usable floor area.

---

5. Special Cases: Spiral Stairs and Open Vides

Certain stair types or open spaces around staircases may raise additional questions:

• Spiral staircases: These are measured in the same way as traditional stairs, following the 4 m² rule for the floor opening.
• Open vides: Open spaces above stairwells (commonly seen in modern homes) are excluded if the opening exceeds 4 m².

---

Summary of Measurement Rules

Feature	Ground-Level Homes	Apartments
Stairwell < 4 m²	Included in usable floor area	Included in usable floor area
Stairwell > 4 m²	Only first 4 m² included	Only first 4 m² included
Space under stairs < 1.5 m height	Included in usable area	Excluded from usable area
Space under stairs ≥ 1.5 m height	Included in usable area	Included if accessible and usable
Shared staircases	Not included in usable area	Not included in usable area
Private staircases	Included in usable area	Included in usable area

---

Why Do These Rules Matter?

Understanding how to measure stairs and stairwells ensures accuracy in calculating usable floor areas. These measurements affect:

• Real estate valuations: Correct floor area measurements are essential for buyers and sellers.
• Tax assessments: Accurate calculations ensure fair property tax evaluations.
• Building designs: Architects and developers can optimize functional spaces by understanding these guidelines.

By following NEN 2580, you can ensure that stairs and stairwells are measured consistently and fairly across all projects.

---

Need More Help?

If you’re unsure how to measure stairs, stairwells, or any related areas, consult a professional or refer to the NEN 2580 standard directly. Accurate measurements are essential for valuations, listings, and compliance.

---

Explainer Video: How to Calculate Living Area and Other Areas

Would you like to quickly and easily learn how to calculate the living area and other surface areas of a home? Watch this video!