Understanding ICC-ES AC39 for Walking Decks
A clear explanation of what Acceptance Criteria AC39 is, why it matters, and how it affects walking deck waterproofing projects.
What is ICC-ES AC39?
AC39 is an acceptance criteria document published by ICC Evaluation Service (ICC-ES) that establishes standardized evaluation guidelines for walking deck systems. Think of it as the rulebook that determines whether a walking deck meets the requirements needed for use in building construction.
The document covers walking deck products that use cementitious coatings, elastomeric coatings, membrane systems or other components applied over new or existing substrates like plywood, concrete, or other substrates. If a product is evaluated under AC39, it means an independent third party has verified it meets specific performance standards and building code requirements. Architects, contractors, and building officials rely on this verification to ensure the materials used in their projects are safe, durable, and code-compliant.
Where AC39 Fits in Construction Specifications
In the CSI MasterFormat system that architects and contractors use to organize construction documents, walking deck systems fall under Division 07 00 00 – Thermal and Moisture Protection. More specifically, they're classified in Section 07 18 13 – Pedestrian Traffic Coatings.
This classification makes sense because walking decks serve two primary functions: they protect the building structure from water infiltration (moisture protection) and they provide a durable walking surface (pedestrian traffic coating). When architects write project specifications, they reference these section numbers to clearly communicate which products and systems are required. ICC-ES listed products provide the technical documentation needed to meet the requirements specified in Division 07.
Current Version: AC39 was approved June 2017 and editorially revised May 2024.
Why AC39 Matters for Your Project
Building Code Compliance
Most jurisdictions in the United States require building products to comply with the International Building Code (IBC) or International Residential Code (IRC). Products evaluated under AC39 can demonstrate compliance with these codes, making the permitting process smoother.
Code Official Acceptance
When a building inspector reviews your plans, they need to verify that specified materials and building products meet the official building code requirements. An ICC-ES evaluation report based on AC39 provides the documentation code officials need to approve your project's walking deck or roof deck waterproofing system.
Performance Assurance
AC39 evaluation isn't just paperwork. Products must pass rigorous testing for structural capacity, fire resistance, wear resistance, and weatherability. This gives you confidence the system will perform as expected.
Project Risk Reduction
Using ICC-ES listed products reduces the risk of installation delays, permit rejections, or performance failures. For architects, contractors, and property owners, this means fewer headaches and less liability.
Key Requirements Covered by AC39
1. Materials & System Components
AC39 specifies acceptable materials for walking deck systems, including the types of coatings, reinforcement, substrates, and adhesives that can be used. Each component must be identified and tested as part of the complete system.
2. Structural Performance
Systems must demonstrate they can support pedestrian traffic loads without failure. Testing verifies the deck surface won't crack, delaminate, or deteriorate under normal walking loads.
3. Fire Resistance
Products are tested per ASTM E84 to determine flame spread and smoke development characteristics. This ensures the deck surface meets fire safety requirements for Class A or Class B ratings.
4. Impact Resistance
AC39 requires testing to verify the deck system can withstand impact from typical use without cracking, delamination, or damage. This ensures the surface maintains its integrity and waterproofing performance in high-traffic areas and under normal pedestrian loads.
5. Wind Resistance
For roof deck applications, AC39 evaluation includes wind uplift testing to ensure the system remains securely attached under high wind conditions. Products are rated for specific wind speeds and exposure categories based on building height and location.
6. Wear Resistance & Durability
AC39 includes testing for abrasion resistance to ensure the surface can withstand foot traffic over time without excessive wear. This is critical for decks in multi-family housing, commercial buildings, and high-traffic areas.
7. Water Resistance
Since the primary purpose of most deck systems is waterproofing, AC39 requires testing to verify the system prevents water penetration and protects the substrate from moisture damage.
8. Slip Resistance
Walking surfaces must provide adequate slip resistance for pedestrian safety. AC39 evaluates the coefficient of friction to ensure the surface isn't hazardously slippery when wet.
9. Installation Requirements
The criteria specify proper installation procedures, including surface preparation, application methods, curing requirements, and quality control measures. This ensures the system performs as tested.
How Products Get Evaluated Under AC39
Manufacturer Submits Application
The product manufacturer applies to ICC-ES for evaluation and provides complete technical documentation about the system components and intended use.
Independent Laboratory Testing
The product undergoes testing at accredited laboratories following AC39 test protocols. This includes fire testing (ASTM E84), structural testing, wear resistance, water resistance, and other performance criteria.
Technical Review
ICC-ES engineers review test results, manufacturing processes, quality control procedures, and installation requirements to verify everything meets AC39 criteria and applicable building codes.
Evaluation Report Issued
If the product passes all requirements, ICC-ES publishes an Evaluation Service Report (ESR). This document becomes the official reference for code compliance and is recognized by building officials nationwide.
Ongoing Surveillance
ICC-ES conducts regular inspections of manufacturing facilities and requires periodic retesting to ensure the product continues to meet AC39 requirements. ESR reports are renewed annually subject to continued compliance.
Real-World Example: ESR-3672
To see AC39 evaluation in practice, you can review ICC-ES ESR-3672, which covers the Deck Flex W.M. and W.F. waterproofing systems.
This evaluation report shows exactly what information ICC-ES provides:
- Which building code editions the product complies with (IBC 2021, 2018, 2015, etc.)
- Approved substrates (plywood, concrete)
- Fire classification (Class A or Class B)
- Wind resistance ratings (up to 130 mph for specific exposure categories)
- Impact resistance verification for pedestrian traffic
- System components and their specifications
- Installation requirements and limitations
- Inspection and quality control procedures
Building officials reference these details when reviewing project submittals. The ESR provides the technical backup needed for permit approval.
Practical Considerations
When is AC39 Evaluation Required?
Requirements vary by jurisdiction and project type. Multi-family residential buildings, commercial properties, and projects requiring building permits typically need code-compliant products. Single-family residential projects may have more flexibility, but using evaluated products is still good practice.
In California, properties subject to SB721 balcony inspection requirements often benefit from ICC-ES listed systems when repairs or replacements are needed, ensuring long-term code compliance and structural integrity.
Not All Deck Products Are Evaluated
Many decking systems and products on the market have not been evaluated under AC39. This doesn't necessarily mean they're bad products, but it does mean they lack independent third-party verification of code compliance and performance. For projects requiring permits or code compliance documentation, unlisted products create real risks and potential project delays.
Installation Must Match Evaluation
The ESR report specifies exactly how the product must be installed. Using different application methods, substrates, or system components than what's listed in the ESR voids the evaluation. Always follow the manufacturer's published specifications that correspond to their ICC-ES report.
ESR Reports Expire
Evaluation reports are renewed annually. Check that the ESR is current and hasn't expired. Most reports list a "subject to renewal" date. Manufacturers must maintain compliance with AC39 and undergo periodic facility inspections to keep their reports active.
Frequently Asked Questions
What is ICC-ES AC39?
AC39 is an acceptance criteria document published by ICC Evaluation Service (ICC-ES) that establishes standardized evaluation guidelines for walking deck systems. It covers deck systems that use cementitious coatings, elastomeric coatings, membrane systems or other components applied over new or existing substrates like plywood, concrete, or other substrates.
Why is AC39 evaluation important?
Products listed under AC39 can demonstrate compliance with the International Building Code (IBC) and International Residential Code (IRC), making the permitting process smoother. AC39 listing provides the documentation code officials need to approve your project and ensures the product has passed rigorous testing for structural capacity, fire resistance, wear resistance, and weatherability.
What does AC39 testing cover?
AC39 evaluation covers materials and system components, structural performance under pedestrian loads, fire resistance per ASTM E84, impact resistance for high-traffic areas, wind resistance for roof deck applications, wear resistance and durability, water resistance, slip resistance for pedestrian safety, and installation requirements including surface preparation and quality control measures.
How do I know if a product is AC39 listed?
Products that have been listed under AC39 will have an ICC-ES Evaluation Service Report (ESR). This report provides complete documentation of the system's compliance with AC39 criteria, including approved substrates, fire classification, system components, installation requirements, and code compliance information.
When is AC39 evaluation required?
Requirements vary by jurisdiction and project type. Multi-family residential buildings, commercial properties, and projects requiring building permits typically need code-compliant products. Single-family residential projects may have more flexibility, but using evaluated products is still good practice.
Do ESR reports expire?
Yes, evaluation reports are renewed annually. Check that the ESR is current and hasn't expired. Most reports list a "subject to renewal" date. Manufacturers must maintain compliance with AC39 and undergo periodic facility inspections to keep their reports active.
Related Resources
Questions About Code Compliance?
Our technical team can help you understand AC39 requirements for your specific project and provide guidance on product selection and code compliance documentation.