Durability Assessment of Coated Cross-Laminated Timber (CLT) Wall and Slab Panels with and without Weather and Vapor Barriers under Coastal Exposure

Sep 15, 2026

Uploaded by Skyler

This study evaluates how weather and vapor-resistive barriers (WRBs) influence the durability of coated cross-laminated timber (CLT) wall and slab assemblies during coastal exposure. Full-scale mock-ups used lab-fabricated CLT panels finished with a three-coat liquid system, with half of each panel additionally covered by a vapor-permeable WRB for side-by-side comparison. Moisture and temperature sensors measured moisture ingress across shallow, mid, and deep layers over three and a half months, aligned with local weather data and durability/mold thresholds. Results show WRBs reduced surface wetting duration by 26 days and improved recovery timing, while deeper layers stayed within safe service ranges, supporting moisture-protection best practices for coastal CLT construction.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages10

Reading Time25 min

AccessFree to download

Durability Assessment of Coated Cross-Laminated Timber (CLT) Wall and Slab Panels with and without Weather and Vapor Barriers under Coastal Exposure

Introduction

Field Evaluation Setup and Monitoring

Results and Implications

EPiC Series in Built Environment Volume 7, 2026, Pages 1132–1141 Proceedings of Associated Schools of Construction 62nd Annual International Conference Durability Assessment of Coated Cross-Laminated Timber (CLT) Wall and Slab Panels with and without Weather and Vapor Barriers under Coastal Exposure Shaghayegh Kurzinski1, Mia Raley 1, Joel Singley 1, Emily Maines 1 1Roger Williams University Cross-laminated timber (CLT) provides environmental and structural advantages; however, moisture management remains a critical challenge for long-term durability, particularly in humid and coastal climates. While commercial liquid-applied coatings are widely used to protect mass timber, the added performance of weather and vapor-resistive barriers (WRBs) under prolonged outdoor exposure remains insufficiently documented. This study presents a comparative field evaluation of coated CLT wall and slab panels, with and without WRB systems, subjected to summer and early-fall coastal exposure in Bristol, Rhode Island. One full-scale mock-up was assembled using lab-fabricated CLT panels. All faces received a three-coat liquid finish, and half of each panel was additionally covered with a vapor-permeable WRB to enable direct side-by-side comparison. Moisture and temperature sensors were installed at three depths (shallow-, mid-, and deep-depth layer) across all conditions. Data collected over a three-and-a-half-month period were analyzed alongside local weather-station records to assess the extent and depth of moisture ingress, the duration of elevated moisture levels above durability and mold-growth thresholds, and the overall effectiveness of WRB protection relative to coated-only assemblies. Results demonstrated that WRB application reduced surface wetting duration by 26 days (from 46 to 20 days above 16% MC) on horizontal shallow surfaces and shortened recovery times, especially on horizontal elements exposed to direct rainfall and ponding, while deeper layers remained largely within safe service ranges. The findings provide evidence-based guidance for best practices in moisture protection ofCLT systems under coastal exposure and support ongoing efforts to develop standardized durability protocols for mass timber construction. Keywords: Cross-Laminated Timber (CLT), Weather Barriers, Moisture Intrusion, Coastal Exposure, Durability Assessment. Introduction Cross-laminated timber (CLT) is primarily used in residential and commercial construction because it offers many environmental and structural benefits (Cappellazzi et al., 2020; Shams et al., 2024) . However, managing the moisture content (MC) of CLT is a primary concern, especially in humid and coastal environments. Exposure to moisture for prolonged periods of time increases the risks of fungal decay, reduces structural durability, and results in deterioration of materials. Commercial liquid-applied coatings are commonly used to protect mass timber, but the additional use of weather resistant barriers (WRBs) is not well studied. Understanding the effects of using a combination of coatings and WRBs is important to developing long-term durability recommendations for CLT structures under coastal conditions. Previous research has consistently emphasized that mass timber products are highly W. Collins, A. Perrenoud and J. Posillico (eds.), ASC 2026 (EPiC Series in Built Environment, vol. 7), Durability of Coated CLT Wall and Slab Panels Kurzinski et al. susceptible to moisture damage, highlighting that the main durability risks come from moisture exposure. Fungal decay risks in mass timber generally occur around a MC of 30%, with more severe risks happening around MCs of 60-80%. Mass timber is typically manufactured with a MC around 12%, so even short-term exposure to rain can drastically elevate MC levels beyond what is safe, leading to swelling, cracking, and glue-lined failures (Cappellazzi et al., 2020) . Similarly, CLT panels exposed to outdoor conditions in Portugal

FAQs

What materials and protective systems were compared in the study?

The research compared coated CLT wall and slab panels with and without vapor-permeable weather-resistive barrier (WRB) systems during coastal exposure.

How was moisture performance measured during the field evaluation?

Moisture and temperature sensors were installed at three depths (shallow, mid, and deep) across all test conditions and analyzed alongside local weather-station records.

What was the main durability benefit of using a WRB in addition to coatings?

WRB application reduced surface wetting duration by 26 days and shortened recovery times, particularly for horizontal elements exposed to rainfall and ponding.

Sep 15, 2026

Uploaded by Skyler