Hi there! I’m Russell McCarthy, the lead building inspector and founder of WA Building Inspections in Perth. In this article, we’ll explore the critical role of roof pitch in preventing water ingress, drawing on a real-life example from a commercial roof inspection I recently conducted at an aged care home in Joondalup. This case highlights how understanding the nuances of roof pitch can make a significant difference in building maintenance and safety.

Todays commercial building inspection in Perth of an aged care home is where I realised most people, including builders and most building inspectors, have no clue about roof pitch. Why?

Nobody could figure out why this roof was leaking. Until I came along…

What is Roof Pitch?

Roof pitch refers to the angle or slope of a roof, expressed as a ratio of the vertical rise to the horizontal span. It is a crucial factor in determining how effectively a roof can shed water and withstand various weather conditions.

 

 

The Importance of Roof Pitch

The correct roof pitch is essential for:

• Water Drainage: Ensuring water flows off the roof efficiently and doesn’t cause water ingress.
• Structural Integrity: Maintaining the roof’s stability.
• Preventing Leaks: Minimising the risk of water ingress.

Case Study: Aged Care Home in Joondalup

In the video above, I performed a commercial roof inspection on an aged care home in Joondalup. The building had persistent water leaks; it also had serious roof undulation by the way, that previous inspectors couldn’t identify. By examining the roof pitch closely, I was able to pinpoint the problem areas.

Overall Pitch vs. Isolated Pitch

Overall Pitch

Overall pitch refers to the average angle of the entire roof structure. It is typically consistent across the roof and is crucial for overall water drainage.

Isolated Pitch

Isolated pitch refers to the slope of specific sections or elements of the roof. This can vary from the overall pitch due to localized factors, such as sagging tiles or structural modifications.

In the Joondalup building and pest inspection: I found that some roof tiles had sunken, changing their isolated pitch. This alteration allowed water to accumulate and penetrate during heavy rain and wind, leading to leaks inside the building.

Minimum Roof Pitch Requirements

Minimum Pitch for Tiled Roofs

The general guideline for the minimum pitch for tiled roofs is around 15 degrees. This ensures proper water runoff and reduces the risk of leaks.

 

Minimum Pitch for Plain Tiles

Plain tiles typically require a steeper pitch, with a minimum of 35 degrees, to ensure effective water shedding.

 

Clay Tile Minimum Pitch

For clay tiles, the minimum pitch is usually around 15 degrees, providing a balance between durability and water drainage.

 

 

 

Shallowest Pitch for Tiled Roofs

The shallowest pitch for tiled roofs is typically around 12.5 degrees. However, achieving this minimum pitch may require additional waterproofing measures to prevent leaks.

 

 

Factors Affecting Roof Pitch Selection

Climate

In areas with heavy rainfall, a steeper pitch is necessary to ensure efficient water drainage.

 

Aesthetic Preferences

The visual appeal of your roof can be influenced by its pitch, with steeper pitches often providing a more dramatic look.

 

Building Codes

Ensure your roof pitch complies with local building regulations to avoid potential issues.

 

Importance of Accurate Roof Pitch Calculations

Accurate roof pitch calculations are vital for:

• Safety: Ensuring the structural integrity of the roof.
• Longevity: Preventing water damage and prolonging the lifespan of the roof.
• Compliance: Meeting building codes and regulations.

My Final Say

Understanding and selecting the correct roof pitch for your tiled roof is essential for ensuring durability and effectiveness. The commercial roof inspection in Joondalup highlighted how variations in isolated pitch can lead to significant issues, such as water ingress. By addressing these pitch issues, we can enhance the safety and longevity of buildings.

For more insights and professional building inspections, visit our 3 branches across Perth:

1) WA Building Inspections Perth

2) WA Building Inspections Rockingham to Mandurah

3) WA Building Inspections Midland

FAQs

 

What is the minimum pitch for a tiled roof?

The minimum pitch for a tiled roof is generally around 15 degrees, though it can vary based on tile type and local codes.

 

What is the minimum pitch for roof tiles?

The minimum pitch for roof tiles is typically around 15 degrees, depending on the type of tile and local building regulations.

 

What is the lowest pitch for roof tiles?

The lowest pitch for roof tiles is usually 12.5 degrees, but this may require additional waterproofing measures to prevent leaks.

 

What is the minimum pitch for concrete roof tiles?

The minimum pitch for concrete roof tiles is typically around 15 degrees, ensuring proper water runoff and structural integrity.