Limiting the fire spread through lightweight framed construction is a well established method of providing fire resistance. The objective is for the barrier to provide fire resistance for the required time, even if at the end of that time it has to be demolished, because of internal damage. This report describes a software tool for predicting the likely fire resistance performance of a non-loadbearing or loadbearing wall subjected to a standard fire resistance test, or when subjected to real fire conditions. Prediction of the performance of fire barriers in this study employed finite difference techniques for heat conduction within linings and also for convection and radiation on the boundaries and cavity. A user-friendly interface was developed for input of the parameters from the lining properties and dimensions, stud sizes, wall height and whether the studs are timber or steel. A choice of fire exposure is also permitted so that 'a standard ISO curve' or 'real fire with a decay period' may be input by the user. Algorithms for the charring of timber and reduction of steel strength and stiffness at elevated temperatures are included to determine a structural failure condition for the studs.