The aim of this investigation was to design and determinate the mechanical properties of innovative, externally invisable joints that can be assembled without the use of tools. The purpose of the paper is to determine the strength, stiffness and modulus of the elasticity of T-type mortise, loose tenon +/ glass fibre reinforced plastic clamping furniture and framing joints under tension, bending and share loads LVS EN 310:2001 [1]and Eurocode 5 [2] for wooden indoor and outdoor structural connections. The samples are made from European spruce (Picea abies Karst.) C 24 class timber LVS EN 14081-2+A1:2016, [3] with relative wood moisture 18%. These samples are assembled with water/ high temperature resistant polyurethane adhesive [4] Kleiberit PUR LVS EN 301:2018 [4]. The European birch (Fagus sylvatica) is used for loose tenon for indoor joints and the Sipo Mahogany (Entandrophragma utile) is used for outdoor joints [ LVS EN 942:2007 [5]. Before gluing and practical tension, bending loads testing the moisture measurement is performed. The total number of samples are 35. The sample width and thickness is 95mm and 45mm. T-type loose tenon +/ glass fibre reinforced plastic clamping furniture joints under tension are 10% stronger than T-type mortise and framing joints but in bending tests were the same results as others joints. The accuracy of the developed strength, stiffness, deformability and elasticity modulus models of the examined joints was verified positively both by experimental studies and numerical calculations.