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

10 pages•Published: June 2, 2026

Shay Kurzinski, Mia Raley, Joel Singley and Emily Maines

Abstract

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 of CLT systems under coastal exposure and support ongoing efforts to develop standardized durability protocols for mass timber construction.

Keyphrases: coastal exposure, cross laminated timber (clt), durability assessment, moisture intrusion, weather barriers

In: Wesley Collins, Anthony Perrenoud and John Posillico (editors). Proceedings of Associated Schools of Construction 62nd Annual International Conference, vol 7, pages 1132-1141.

Links:	https://easychair.org/publications/paper/gnbZ
	https://doi.org/10.29007/5xtt

BibTeX entry

@inproceedings{ASC2026:Durability_Assessment_Coated_Cross,
  author    = {Shay Kurzinski and Mia Raley and Joel Singley and Emily Maines},
  title     = {Durability Assessment of Coated Cross-Laminated Timber (CLT) Wall and Slab Panels with and without Weather and Vapor Barriers under Coastal Exposure},
  booktitle = {Proceedings of Associated Schools of Construction 62nd Annual International Conference},
  editor    = {Wesley Collins and Anthony Perrenoud and John Posillico},
  series    = {EPiC Series in Built Environment},
  volume    = {7},
  publisher = {EasyChair},
  bibsource = {EasyChair, https://easychair.org},
  issn      = {2632-881X},
  url       = {/publications/paper/gnbZ},
  doi       = {10.29007/5xtt},
  pages     = {1132-1141},
  year      = {2026}}

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