Australian bushfires have repeatedly killed many people and caused severe damage. Previous studies have identified direct flame contact and radiant heat as the main cause of fatalities. The role of screens to limit the radiation exposure of an object by a fire on the opposite side of the screen is well-known, but still it has not been experimentally quantified. A screen between a radiation source and an object divides the radiant heat flux (RHF) into two parts. The first part is the direct RHF (DRHF) that passes directly through the screen without any interaction. The second part is indirect RHF (IRHF), which includes both emitted and reflected RHFs by the heated screen. This experimental study deals with the DRHF, which is dependent on the screen porosity and is independent of the material composition or the surface quality of the screen. The experimental results of four square-cell, plain woven screens, with porosities ranging from 41% to 66%, show that the passing ratios (PRs) of DRHF through screens are less than those suggested by their porosity. Four empirical equations have been developed to determine the PR of the direct radiation through screen and the tunnel vision angles of the screens.