--- title: "Understanding Rule 85: Construction Classes" description: Discover how different building construction types impact class ratings and insurance costs in Part II of our series on Understanding Rule 85. image: https://www1.wsrb.com/hubfs/CC%20-%20headewr.jpg --- [![Go to WSRB](https://www1.wsrb.com/hs-fs/hubfs/images/logos/wsrb-logo-white.png?width=120&height=20&name=wsrb-logo-white.png "Go to WSRB")](https://www1.wsrb.com/) [![Go to BuildingMetrix](https://www1.wsrb.com/hs-fs/hubfs/buildingmetrix/logo/inactive-BMI-1.png?width=140&height=23&name=inactive-BMI-1.png "Go to BuildingMetrix")](https://www.buildingmetrix.com/) [![Washington Surveying & Rating Bureau logo](https://www1.wsrb.com/hs-fs/hubfs/images/logos/wsrb-horiz-logo-rgb.png?width=150&height=51&name=wsrb-horiz-logo-rgb.png "Washington Surveying & Rating Bureau logo")](https://www1.wsrb.com/) [![CREATE AN 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and excellent customer service.  #### [Careers](https://www1.wsrb.com/careers) Learn about the benefits of working at WSRB and apply for open positions.   #### [Underwriting Property](https://www1.wsrb.com/resources/underwriting-property-risks) A guide to key risks in Washington state: fire, wildfire, and earthquakes. --- #### [Video Hub](https://www1.wsrb.com/video) Expert webinars, timely discussions, and in-depth conversations with industry leaders..  #### [Commercial Property](https://www1.wsrb.com/risk-assessment-guide) Information on loss costs, policy rating, and assessment tools.   --- #### [Industry Toolkit](https://www1.wsrb.com/resources/industry-toolkit) Links to help you work smarter and serve your customers.   #### [Protection Classes](https://www1.wsrb.com/resources/public-protection) The evaluation process explained from start to finish. --- #### [WSRB Blog](https://www1.wsrb.com/blog) News on emerging risks as well as our latest products.  #### [Library](https://www1.wsrb.com/library) In-depth content on essential insurance topics. --- #### [InsuranceEDGE](https://www1.wsrb.com/insuranceedge) Weekly newsletter covering the P/C industry, curated by our experts.  Search **Search filters** Website pages Blog posts Help Center articles Include results from BuildingMetrix.com [![wsrb_white-logo](https://www1.wsrb.com/hs-fs/hubfs/wsrb_white-logo.png?width=100&height=17&name=wsrb_white-logo.png "wsrb_white-logo")](https://www1.wsrb.com/) ** ** ![](https://www1.wsrb.com/hubfs/CC%20-%20headewr.jpg) [Loss Costs](https://www1.wsrb.com/blog/tag/loss-costs) | [Construction Class](https://www1.wsrb.com/blog/tag/construction-class) | 4 min read # Understanding Rule 85: Construction Classes By [Chris Barclay](https://www1.wsrb.com/blog/author/chris-barclay) September 2, 2025 This is Part II of our [six-part series on Understanding Rule 85](https://help.wsrb.com/understanding-rule-85). In this series, we delve into the intricacies of Rule 85 and its implications for property insurance. In this installment, we will delve into the different construction types, exploring how they are defined, providing examples, and discussing their importance in class ratings. ## Construction classes The construction type of a building plays a crucial role in its class rating, influencing its risk profile and insurance costs. Here, we define and provide examples of the seven primary construction types used in class ratings. #### ![CC-Frame-1](https://www1.wsrb.com/hs-fs/hubfs/CC-Frame-1.jpg?width=2000&height=188&name=CC-Frame-1.jpg) #### CC 1: Frame **Definition:** [Frame construction](https://help.wsrb.com/the-basics-on-construction-classes#frame) buildings have exterior walls made of wood or other combustible materials. Includes structures with a combination of combustible materials and other types, such as brick veneer, stone veneer, or stucco on wood. **Examples:** - Wood-framed houses - Small commercial buildings with wood or metal siding - Residential structures with wooden supports **Importance in class rating:** Frame construction is common in residential properties due to its cost-effectiveness and ease of construction. It generally carries a higher insurance premium due to increased fire risk. #### ![CC-Joisted Masonry](https://www1.wsrb.com/hs-fs/hubfs/CC-Joisted%20Masonry.jpg?width=2000&height=188&name=CC-Joisted%20Masonry.jpg) #### CC 2: Joisted Masonry **Definition:** [Joisted Masonry construction](https://help.wsrb.com/the-basics-on-construction-classes#joisted-masonry) buildings have exterior walls made of masonry materials such as adobe, brick, concrete, gypsum block, stone, or tile, with combustible floors and roofs. **Examples:** - Commercial buildings with brick/stone exteriors and wooden roofs - Apartment complexes with masonry walls - Warehouses with reinforced masonry walls **Importance in class rating:** Joisted Masonry offers better fire resistance than Frame construction, potentially resulting in lower insurance premiums. Its balanced use of materials provides moderate protection against fire. #### ![CC-Non-Combustible-1](https://www1.wsrb.com/hs-fs/hubfs/CC-Non-Combustible-1.jpg?width=2000&height=188&name=CC-Non-Combustible-1.jpg) #### CC 3: Non-Combustible **Definition:** [Non-Combustible construction](https://help.wsrb.com/the-basics-on-construction-classes#noncombustible) buildings have exterior walls, floors, and roofs constructed of and supported by metal, asbestos, gypsum, or other non-combustible materials. **Examples:** - Industrial buildings with steel frames and concrete floors - Commercial structures with metal roofs and walls - Warehouses with reinforced concrete walls **Importance in class rating: **Non-combustible buildings are more favorable in class ratings, potentially reducing insurance costs due to their enhanced fire protection (often used in industrial and commercial applications where fire risk needs to be minimized). ![CC - Masonry Non-Combustible-1](https://www1.wsrb.com/hs-fs/hubfs/CC%20-%20Masonry%20Non-Combustible-1.jpg?width=2000&height=188&name=CC%20-%20Masonry%20Non-Combustible-1.jpg) #### CC 4: Masonry Non-Combustible **Definition:** [Masonry Non-Combustible construction](https://help.wsrb.com/the-basics-on-construction-classes#masonry-noncombustible) buildings have exterior walls constructed of masonry materials, with floors and roofs made of metal or other non-combustible materials. **Examples:** - Factories with brick walls and steel roofs - Schools with concrete block walls and metal flooring - Office buildings with stone exteriors and non-combustible interiors **Importance in class rating:** Masonry Non-Combustible buildings combine the durable masonry with fire resistant non-combustible materials, offering a balance of protection and cost-effectiveness. #### ![CC - Modified Fire-Resistive-1](https://www1.wsrb.com/hs-fs/hubfs/CC%20-%20Modified%20Fire-Resistive-1.jpg?width=2000&height=188&name=CC%20-%20Modified%20Fire-Resistive-1.jpg) #### CC 5: Modified Fire-Resistive **Definition:** [Modified Fire-Resistive construction](https://help.wsrb.com/the-basics-on-construction-classes#modified-fire-resistive) buildings have exterior walls, floors, and roofs constructed of masonry or fire-resistive material with a fire-resistance rating of between one and two hours. **Examples:** - Mid-rise office buildings with reinforced concrete and fireproofing - Retail centers with masonry walls and protected steel structures - Mixed-use buildings with enhanced fire resistance **Importance in class rating:** Modified Fire-Resistive buildings provide a moderate level of fire protection suitable for many commercial applications; often lead to favorable insurance premiums due to enhanced safety features. #### ![CC - Fire-Resistive-1](https://www1.wsrb.com/hs-fs/hubfs/CC%20-%20Fire-Resistive-1.jpg?width=2000&height=188&name=CC%20-%20Fire-Resistive-1.jpg) #### CC 6: Fire-Resistive **Definition:** [Fire-Resistive construction](https://help.wsrb.com/the-basics-on-construction-classes#fire-resistive) buildings have exterior walls, floors, and roofs constructed of masonry or fire-resistive materials with a fire-resistance rating of more than two hours.  **Examples:** - High-rise buildings with reinforced concrete and steel structures - Government and institutional buildings with advanced fireproofing - Hospitals and medical facilities with fire-resistive materials **Importance in class rating:** Fire-Resistive buildings have the highest level of fire protection, often resulting in the lowest insurance premiums. #### ![CC - Mixed-1](https://www1.wsrb.com/hs-fs/hubfs/CC%20-%20Mixed-1.jpg?width=2000&height=188&name=CC%20-%20Mixed-1.jpg) #### Mixed construction **Definition:** [Mixed Construction](https://help.wsrb.com/the-basics-on-construction-classes#mixed-construction) refers to buildings that incorporate elements from several construction classes. Determining the class rating for mixed construction involves assessing the predominant materials and their fire resistance. **Examples:** - Buildings with a combination of masonry and steel in various sections - Complex structures with different floors having different construction classes - Renovated buildings with updated fireproofing and structural materials **Handling mixed construction:** Accurately classifying mixed construction requires a detailed understanding of the building’s design and materials. Insurers may need to consider specific sections individually to determine the overall class rating and insurance premiums. ## Importance of construction type in class ratings Construction type is an important factor for determining a building's class rating, influencing the overall risk assessment and insurance premiums. Here's why: **Risk assessment:** Fire-resistant construction types typically have lower risk profiles, leading to more favorable class ratings. **Insurance premiums:** Buildings with better fire resistance often qualify for lower premiums. **Compliance and safety:** Knowing the construction type helps property owners comply with safety regulations and building codes, reducing legal issues and liabilities.  -- -- -- For more information on construction classes, check out [WSRB's Basics on Construction Classes](https://help.wsrb.com/the-basics-on-construction-classes). Up next is Part III of our Understanding Rule 85; explore the impact of occupancy on class ratings and how it affects insurance policies. Chris Barclay spent 30 years underwriting personal, commercial and agricultural lines in the Western U.S. before joining WSRB to develop innovative, easy-to-use tools that help insurers manage both entire portfolios and individual accounts. Chris lives and works in Spokane, Washington. Connect with me on [LinkedIn](https://www.linkedin.com/in/chris-barclay-cpcu-afis-are-919409a1/) ## You May Also Like These stories on Loss Costs [![](https://www1.wsrb.com/hubfs/85-part-vi-featured.jpg) ](https://www1.wsrb.com/blog/understanding-rule-85-specialized-class-rates) [Loss Costs](https://www1.wsrb.com/blog/tag/loss-costs) ### [Understanding Rule 85: Specialized Class Rates](https://www1.wsrb.com/blog/understanding-rule-85-specialized-class-rates) September 2, 2025 | 2 min read [![](https://www1.wsrb.com/hubfs/ineligible-featured.jpg) ](https://www1.wsrb.com/blog/understanding-rule-85-ineligible-for-class-rates) [Loss Costs](https://www1.wsrb.com/blog/tag/loss-costs) ### [Understanding Rule 85: Ineligible for Class Rates](https://www1.wsrb.com/blog/understanding-rule-85-ineligible-for-class-rates) September 2, 2025 | 4 min read [![](https://www1.wsrb.com/hubfs/85-part-iv-featured.jpg) ](https://www1.wsrb.com/blog/understanding-rule-85-who-is-class-rated) [Loss Costs](https://www1.wsrb.com/blog/tag/loss-costs) ### [Understanding Rule 85: Who is Class Rated?](https://www1.wsrb.com/blog/understanding-rule-85-who-is-class-rated) September 2, 2025 | 2 min read Previous Story [← Understanding Rule 85: What is Class Rated?](https://www1.wsrb.com/blog/understanding-rule-85-what-is-class-rated) [** ](https://www1.wsrb.com/blog) Next Story [Understanding Rule 85: The Rating Process →](https://www1.wsrb.com/blog/understanding-rule-85-rating-process) ![blog listing blog sign up](https://www1.wsrb.com/hubfs/images/website/blog%20listing%20blog%20sign%20up.jpg "blog listing blog sign up") ### Sign up for our blog ![Washington Surveying & Rating Bureau logo](https://www1.wsrb.com/hs-fs/hubfs/wsrb_white-logo.png?width=200&height=34&name=wsrb_white-logo.png "Washington Surveying & Rating Bureau logo") Phone: 206-217-0101 Hours: 7:30 AM - 4:00 PM   [Site Map](https://www1.wsrb.com/vis-sitemap) COMPANY RESOURCES FROM OUR BLOG Copyright © 1911 – 2026 WSRB. 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