The entry of soil gas pollutants into buildings has been the subject of many studies and some analytical airflow models have been developed to estimate this entry into buildings. The existing airflow models do not include the sub-slab gravel layer that can influence significantly the airflow from soil into buildings. In this paper, an analytical airflow model, which considers this sub-slab gravel layer has been developed. Moreover, a 2D finite-element model has been used for numerical comparison. This comparison gave a satisfactory agreement with the analytical model. The airflow model is presented as flow-pressure equation and can be integrated easily in vapour intrusion models or ventilation models to enable the quantification of the impact of these pollutants on indoor air quality.