CROSS LAMINATED TIMBER (CLT) IS A PANELIZED PRODUCT THAT UTILIZES DIMENSIONAL LUMBER GLUED IN AN ORTHOGONAL MANNER TO CREATE MASS TIMBER PANELS THAT CAN BE USED IN HORIZONTAL AS WELL AS VERTICAL MEMBERS IN A BUILDING SYSTEM. CLT ENABLE UTILIZATION OF WOOD IN THE MID-RISE BUILDING MARKET, WHERE TIMBER HISTORICALLY HAS NOT BEEN THE MATERIAL OF CHOICE. SEVERAL BUILDINGS INVOLVING CLT HAVE EITHER BEEN COMPLETED OR BROKEN GROUND, SEVERAL OTHER PROJECTS INVOLVING CLT ARE IN INCEPTION AND DESIGN STAGES. IT IS EVIDENT THAT CLT IS GAINING ACCEPTANCE IN TALL BUILDING APPLICATIONS IN THE US. HOWEVER, THERE ARE KNOWLEDGE GAPS CONCERNING LONG-TERM PERFORMANCE, PARTICULARLY EFFECTS DUE TO MOISTURE INTRUSION AND BIOLOGICAL DECAY IN RELATION TO CONNECTION SYSTEMS. WHILE MOISTURE IS THE ENEMY OF ALL BUILDING MATERIALS, IT CAN BE PARTICULARLY DETRIMENTAL TO WOOD-BASED SYSTEMS BECAUSE IT INTRODUCES THE POSSIBILITY OF BIOLOGICAL DETERIORATION. THE WOOD-BASED COMPOSITES USED IN MASS TIMBER CONSTRUCTION CAN BE EVEN MORE VULNERABLE BECAUSE THE DIMENSIONAL CHANGES ASSOCIATED WITH WETTING LEAD TO PERMANENT LOSSES IN MATERIAL PROPERTIES, WHICH IN TURN HAVE AN ADVERSE EFFECT ON CONNECTION STRENGTH. THIS COULD BE DETRIMENTAL AS CONNECTION PERFORMANCE IS CRITICAL FOR THE INTEGRITY OF ALL CLT STRUCTURES.IN A RISK-AVERSE INDUSTRY, THIS KNOWLEDGE GAP IMPEDES ACCEPTANCE OF CLT. THE OVERALL GOAL OF THE PROJECT IS TO CHARACTERIZE THE EFFECTS OF MOISTURE ACCUMULATION IN MASS TIMBER BUILDINGS ON PROPERTIES OF BUILDING COMPONENTS AND CONNECTIONS. THE PROJECT WILL ASSESS CLT CONNECTORS USING SMALL-SCALE ASSEMBLIES, THEN USE THESE DATA TO DEVELOP PREDICTIVE MODELS THAT WILL BE COMPARED WITH FULL-SCALE TESTS. CONNECTION ASSEMBLIES WILL BE CONSTRUCTED WITH TWO WOOD SPECIES AND EXPOSED TO FIVE MOISTURE/BIOLOGICAL REGIMES. MOISTURE BEHAVIOR IN THE ASSEMBLIES WILL BE CHARACTERIZED USING A COMBINATION OF NON-DESTRUCTIVE TOOLS, SUCH AS ULTRASONIC, WAVE PROPAGATION, CAT-SCAN, AND INFRARED IMAGING. THE DATA GENERATED FROM CYCLIC LOADING TESTS WILL BE USED TO CALIBRATE EXISTING ENGINEERING CONNECTION MODELS. THIS WILL PROVIDE A NOVEL WAY TO ESTIMATE THE EFFECTS OF MOISTURE AND BIOLOGICAL DEGRADATION ON CONNECTIONS. A DELIVERABLE FOR THIS PROJECT IS A DESIGN GUIDELINE FOR ENGINEERS TO ACCOUNT FOR THE EFFECTS OF MOISTURE INTRUSION AND SUBSEQUENT FUNGAL DECAY ON PANEL AND CONNECTION PROPERTIES.