Timber trusses with punched metal plate fasteners are designed as plane structures loaded only in their plane. Actions applied perpendicularly to the truss plane must be transferred by engineered bracing system. Correct design of the bracing system is considered to be one of the essential conditions providing required reliability of the whole roof structure. The CTU in Prague, Faculty of Civil Engineering, Department of Steel and Timber Structures in cooperation with company Vazníky D.N.K. s.r.o. have performed load tests of three different types of engineered bracing truss structures. The aim of the tests was to describe behaviour of the specimen under horizontal load. Numerical model of two common types of bracing frames and a model of a whole roof consisting of 10 timber trusses was made to verify the results obtained from the experiment.