Thoron isotope has been growing in importance in the last years because, despite of its short half-life, can also contribute in the development of lung cancer. In this work, we assess the thoron massic exhalation rate and emanation factor of some building materials commonly used in the Iberian Peninsula. A continuous thoron monitor was used to measure the thoron activity growth as a function of time. To calculate the emanation factor, the activity of thoron radionuclide mother element (Th-232) by gamma spectrometry was employed. The exhalation rate values range from 0.0007 to 0.040 Bq•kg−1•s−1 for gypsum and Gris Quintana granite, respectively and the emanation factor range from 0.2 to 4.8% for Gran Beige and Gris Quintana granites, respectively. Ranges of results of all these parameters are in good agreement with the values reported by other authors for building materials of different countries.