Shielding Multiplier/Factor (Ms)

Overview

The Shielding Multiplier/Factor (Ms) is used to determine the level of shielding at a building site. It directly influences wind load calculations by adjusting for how much protection the building receives from surrounding structures.

Why this is important

• Affects how wind pressure is calculated on the structure

• Ensures buildings are engineered correctly for site-specific conditions

• Helps sales and estimating teams provide accurate quotes and assessments

Shielding categories

There are four standard shielding values used in design:

• 1.00 (None) – Fully exposed site

• 0.95 (Partial) – Some shielding present

• 0.90 (Intermediate) – Moderate surrounding development

• 0.85 (Full) – Fully shielded from all directions

🛈 The green circle used in assessments refers to a 100 m radius around the proposed building.

Key considerations

When determining the appropriate shielding factor, keep in mind these three important rules:

1. Building height requirements

Only buildings with a height equal to or greater than the proposed structure are deemed to provide shielding.

Example:
If the proposed building is 5 m high and a nearby house is only 3 m high, the house does not provide shielding.

2. Sector assessment

Each 45° sector (covering all 8 cardinal directions) must be assessed individually for potential shielding.

3. Vegetation exclusion

Trees or vegetation do not qualify as shielding under the code—only structures do.

Determining shielding

When determining shielding, also consider:

• The current site conditions, as well as

• Any probable future development expected within the next 5 years

Use Questions A and B in the system to document your observations and conclusions.

Tips & best practices

• Evaluate each direction from the proposed site—use a top-down view

• Reassess if the building design or site conditions change

• If unsure, escalate to Engineering via the Request Engineering – Site Check form

Related Resources

Site Specific Engineering

Request Engineering (Site Check)