Fire represents a serious challenge for the safety and integrity of building structures, especially timber structures t exposed to high temperatures and intense heat radiation. However, timber does not significantly change its mechanical properties during a fire. The reason for this is that carbon layer forms on the surface of the wood shortly after a fire, which prevents heat from developing into the interior of the element. However, the combustibility of timber is one of the main reasons why regulations strictly limit timber as a building material, especially for the construction of multi-storey buildings. Therefore, the most important requirement for the use of timber in buildings is to ensure adequate fire resistance, through passive and active fire protection measures. In this work, a numerical simulation of the effects of fire loads on CLT as integral component of load-bearing structures, is carried out. A overreview of the state of the research in this field shows that there is a lack of research in the field of numerical (FEM and CFD) simulations of timber structures exposed to fire loads. In this work, the influence of the geometric and material propierties of CLT and fire protection systems on the spread of fire, the charring rate, and ultimately, the fire resistance of timber elements is investigated. In the Republic of Croatia, there are no fire safety requirements that apply specifically to timber structures - all requirements are based on to the structure group defined in the Regulation on Fire Resistance and other requirements that buildings must meet in the event of a fire. The result of such an approach is over dimensioning of building components and very often unnecessary or insufficiently argued fire protection of load-bearing timber structures, which requires high financial investments. In order to avoid unnecessary costs, calculation methods and/or models based on the latest achievements in the field of fire resistance can be used in the design of timber structures, which is also the practical contribution of this work.