CAT Rated Sheathing – The Ultimate Resource 2024

cat rated sheathing

CAT (Continuous Annealed Tin) rated sheathing is a specialized type of structural sheathing material commonly used in construction. It consists of plywood or OSB (oriented strand board) panels that have been coated with a layer of continuous annealed tin – hence the name.

What Does it Do Exactly?

CAT rated sheathing plays a crucial role in building structures by providing a reliable barrier against moisture, mold, and corrosion. Its unique construction and protective coating make it particularly suitable for use in environments prone to high humidity or exposure to the elements.

Characteristics of CAT Rated Sheathing


CAT rated sheathing is made from plywood or OSB panels that are treated with a layer of continuous annealed tin. This coating provides additional protection against corrosion, moisture, and other environmental factors, enhancing the durability and longevity of the sheathing material.

Strength and Durability

CAT rated sheathing boasts structural integrity and durability, making it suitable for use in various building applications. The coating provides a high strength-to-weight ratio, contributing to the overall stability and reliability of building structures.

Fire Resistance

The coating provides an additional layer of protection against fire, helping to slow down the spread of flames and reduce the risk of structural damage.

Applications of CAT Rated Sheathing


CAT rated sheathing helps distribute the weight of the roof evenly across the structure, enhancing structural integrity and preventing sagging or deformation. Its protection against moisture infiltration ensures that the roof can outlast a variety of weather conditions.

Wall Sheathing

In wall construction, CAT rated sheathing spreads sideways pressure and blocks moisture, strengthening walls against wind and water damage. It also helps keep the inside temperature stable, making buildings more energy-efficient and comfortable.


CAT rated sheathing is often used in subflooring to make a strong, even surface for flooring. It supports heavy loads, keeps floors from bending too much, and makes it easier to lay flooring materials. It also stops moisture from getting into the floor, lowering the chance of mold and damage.

Benefits and Limitations of CAT Rated Sheathing

Benefit: Strength and Durability

CAT rated sheathing provides excellent structural integrity and durability, making it suitable for supporting heavy loads and withstanding various environmental conditions.

Benefit: Fire Resistance Properties

The coating provides enhanced fire resistance, helping to slow down the spread of flames and reduce the risk of structural damage in the event of a fire.

Limitation: Cost Considerations

CAT rated sheathing costs more than standard sheathing materials such as OSB or plywood. The additional cost may impact overall project budgets, particularly for large-scale construction projects or those with tight financial constraints.

Limitation: Availability in Certain Regions

CAT rated sheathing may not be readily available in all regions or markets. Limited availability can pose challenges for builders and contractors seeking to incorporate CAT rated sheathing into their projects, potentially leading to delays or higher material costs.

Installation Techniques

Roofing Installation

Start by laying the sheathing panels perpendicular to the roof trusses or rafters, staggering the joints for added strength. Use nails or screws, and follow manufacturer recommendations for spacing and placement. Consider using adhesives or sealants to enhance waterproofing and weatherproofing.

Wall Sheathing Installation

Begin by attaching CAT rated sheathing panels vertically or horizontally to the exterior framing members, ensuring a tight fit and proper alignment. Secure the panels with nails or screws. Consider adding additional framing or bracing to improve structural integrity. Seal any gaps or penetrations with flashing tape or sealant to prevent moisture infiltration.

Subflooring Installation

Start by laying the panels perpendicular to the floor joists, with edges supported by framing members. Ensure a tight fit between panels to minimize gaps and prevent squeaking or flexing underfoot. Secure the panels to the joists with nails or screws. Consider adding a layer of moisture barrier or underlayment beneath the sheathing.

Maintenance and Care of CAT Rated Sheathing

Cleaning and Inspection

Regularly clean CAT rated sheathing with a soft brush or mild detergent to remove debris and dirt. Inspect for damage such as cracks or corrosion.

Repairs and Remediation

Should any damage occur, consider patching, sealing, or replacing the affected areas. Seek advice from qualified professionals for appropriate repair techniques and materials.

Preventive Measures

Ensure proper drainage and ventilation around the building envelope to minimize moisture buildup and reduce the risk of mold growth. Apply protective coatings or sealants to vulnerable areas to enhance durability and resistance to environmental factors.

Environmentally Friendly Practices

Recycled Materials

Some CAT rated sheathing products incorporate recycled materials, reducing reliance on new resources and diverting waste from landfills. Look for certifications or endorsements indicating recycled content.

Sustainable Practices

Look for certifications like Forest Stewardship Council (FSC) or Sustainable Forestry Initiative (SFI). Opt for efficient installation techniques to minimize waste, and consider recycling or repurposing old sheathing materials when possible.

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