Cant Strips for Roofing: Essential Guide to Benefits and Installation
Cant strips are vital components in roofing construction, particularly in commercial and flat roofing systems. They serve as transitional pieces between horizontal roofing decks and vertical surfaces like walls or parapets, ensuring smooth water drainage and enhancing overall roof durability. Understanding the function, materials, and correct installation of cant strips is essential for roofing professionals and property owners investing in roof longevity and weatherproofing.
| Aspect | Details |
|---|---|
| Purpose | Provides a smooth transition between roof deck and vertical surfaces |
| Common Materials | Wood, Asphalt-impregnated fiberboard, Foam |
| Benefits | Prevents membrane cracking, improves drainage, increases roof life |
| Typical Locations | Roof edges, parapet walls, curbs, chimneys, skylights |
| Installation Basics | Proper angle formation, secure attachment, compatible with roofing membrane |
What Are Cant Strips in Roofing?
Cant strips are triangular-shaped wedge materials installed at the intersection where the flat roof deck meets a vertical surface. Their primary role is to create a gradual slope, typically at a 45-degree angle, allowing roofing membranes to bend without stress or cracking. Without cant strips, roofing materials can experience premature damage due to sharp bends and water accumulation.
Typically, cant strips are made from different materials like wood, asphalt board, or rigid foam, selected based on the roofing system and environmental exposure. Their size typically ranges to accommodate standard roofing membrane specifications.
Key Benefits of Using Cant Strips in Roofing
- Enhanced Roof Durability: By eliminating sharp angles, cant strips help prevent membrane tears and wear, extending roof life.
- Improved Water Drainage: The angled transition reduces water pooling near vertical surfaces, minimizing leaks and water damage.
- Structural Support: They provide additional support for flashing and membrane attachment, promoting roof integrity.
- Simplified Installation: Cant strips offer a prepared surface for roofers, reducing installation errors and speeding the roofing process.
Materials Commonly Used for Cant Strips
Choosing the right cant strip material depends on roof type, environmental conditions, and budget considerations.
| Material | Pros | Cons |
|---|---|---|
| Wood (Pine or Fir) | Easy to cut and install, inexpensive | Prone to rot and moisture damage if untreated |
| Asphalt-Impregnated Fiberboard | Water resistant, compatible with asphalt roofing systems | Can degrade over time under UV exposure |
| Rigid Foam (Polyisocyanurate, EPS) | Lightweight, excellent insulation, moisture resistance | Higher initial cost, must be covered properly |
Where to Install Cant Strips on a Roof
Cant strips are installed primarily at points where flat or low-slope roofs meet vertical elements:
- Parapet Walls: Creating a smooth angle where the wall meets the roof deck.
- Roof Curbs: Around rooftop equipment bases for waterproofing.
- Chimneys and Skylights: Preventing membrane stress at corners and vertical edges.
- Drainage Fixtures: Assisting water flow near scuppers and internal drains.
Step-by-Step Guide to Installing Cant Strips
Installation accuracy is crucial to maximize cant strip effectiveness:
- Preparation: Clean the roof deck area thoroughly and ensure surfaces are dry.
- Measure and Cut: Cut cant strips to the right length and angle, typically forming a 45-degree bevel.
- Attachment: Secure strips to the roof deck using nails or adhesives suitable for the roofing system.
- Sealing Edges: Ensure overlaps between cant strips and roof membrane are fully sealed to prevent water intrusion.
- Membrane Installation: Carefully apply roofing membranes, allowing the cant strips to guide membrane transitions without wrinkles or air pockets.
Common Mistakes to Avoid When Using Cant Strips
- Ignoring Proper Angles: Using strips without proper bevels can cause membrane stress.
- Improper Securing: Loose cant strips may shift and damage roofing materials.
- Skipping Moisture Barriers: Failure to use compatible waterproof barriers can lead to rot and deterioration.
- Overlooking Roof Design: Not consulting roof plans may result in inappropriate cant strip placement or dimensions.
How Cant Strips Impact Roof Maintenance and Longevity
Properly installed cant strips significantly contribute to minimizing roof maintenance costs and prolonging roof service life. They help prevent common issues such as membrane cracks and water intrusion at critical roof junctions. Regular inspection of cant strips is recommended during roof maintenance checks to ensure they remain intact and effective against weather challenges.
Environmental Considerations and Sustainable Options
With increasing emphasis on sustainability, selecting environmentally friendly cant strip materials is gaining importance. Foam-based strips like polyisocyanurate provide added insulation benefits, contributing to energy efficiency. Meanwhile, treated wood options sourced from sustainable forestry provide eco-friendly choices for buildings prioritizing green construction.
Integration of Cant Strips with Modern Roofing Systems
Modern roofing systems, including Built-Up Roofing (BUR), Modified Bitumen, and Single-Ply Membranes (TPO, EPDM), rely on cant strips for seamless edge transitions and flashing support. Manufacturers often provide guidelines on compatible cant strip materials to ensure optimal adhesion and performance within specific roofing assemblies.
Professional Recommendations for Cant Strip Installation
- Consult local building codes and roofing standards to ensure compliance.
- Use materials compatible with the roofing membrane and environmental conditions.
- Hire experienced roofing contractors for precision installation.
- Schedule periodic inspections focused on cant strip integrity and membrane condition.