Window slopes are one of the most important linear elements of external wall structures with two-dimensional and even three-dimensional temperature field. Thereby, they cause additional risk of non-compliance of sanitary and hygienic requirements. In the proposed work one of the typical designs of window slopes is considered as the object of study, namely the fastening of the window unit with steel fixings to one of the two major layers of the wall – insulation or constructive. Peculiarities of designing two-dimensional stationary temperature field in the structure of the site abutting window units to the aperture of residential and public buildings are considered. Results of calculation of temperature in hazardous adjunction points for the design winter conditions with the help of software that implements the finite element method are presented. The analysis of the obtained data is given and the comparison of the behavior of minimum temperatures in the zone of adjacency of the fill of the lighting aperture with the results of analytical calculation based on the conform transformation for the concave corner is proposed if you move the window block in the cross section of the outer wall. It was discovered that the closer the fill to the outer plane of the facade a minimum of the temperature decreases according to the law which coincides enough closely with the analytical solution. Recommendations on the optimal placement of fill within the structural layer of the wall for the best sanitary-hygienic requirements for outdoor enclosures are confirmed. The presentation is illustrated with examples of temperature fields for the node of adjunction in a residential building on one of the modern projects.