The International Association of Geodesy (IAG) introduced and defined, in 2015, the International Height Reference System (IHRS) as the conventional reference system for the global physical height determination. Following the conventions for the realisation of the IHRS, i.e. the determination of the International Height Reference Frame (IHRF), we utilize the existing GNSS reference stations in Denmark, The Faroe Islands, and Greenland to determine a local densification of the IHRF in these regions. The physical heights of these Danish, Faroese and Greenlandic GNSS reference stations have been transformed from the local Danish, Faroese, and Greenlandic height systems, DVR90, FVR09 and GVR16, respectively, to geopotential numbers and normal heights referring to the IHRF. The offset to the IHRF is found to be −44.0 ± 1.9 cm, −59.8 ± 5.1 cm and − 54.1 ± 11.3 cm for the DVR90, FVR09 and GVR16, respectively. This transformation relies on the existing precise local (quasi-)geoid models. This contribution describes the applied procedures in the IHRF densification and discusses the quality assessment of the results.