_____________________ Jorge M. Branco ISISE, University of Minho, Civil Engineering Department Campus de Azurém 4800-058 Guimarães, Portugal email: jbranco@civil.uminho.pt Roberto Tomasi University of Trento, Department of Structural and Mechanical Engineering Via Mesiano 70, 38100 Trento, Italy email: roberto.tomasi@ing.unitn.it Wood in Floors and Roofs Jorge M. Branco, Roberto Tomasi Abstract In many countries, traditional construction comprises floors and roofs systems in wood. Current knowledge assumes the need to preserve and to protect existing wood sys- tems with important advantages to the overall behaviour of the building. In this paper, after a description of the most common systems used in traditional wooden floors and roofs, strengthening techniques are presented. For that, the analysis and design of the existing structures is discussed and the effectiveness of the strengthening techniques is evaluated through experimental results obtained in laboratory. Key Words: Floors, Refurbishment, Trusses, Traditional connections, Strengthening.