This was a 4000 sq ft garage with the exiting roof for over 50 years! This one had no life left and was patched a few hundred times. We purchased the building and are in the process of converting it into our Headquarters. It was one original building and had 2 additions over the years. This meant different sag levels and heights we have to accomadate for. So this was a full tear off of existing flat roof and all the layers along with fiber board which became dust! We then mechanically fastened Protectoboard ( a fiber glass sheet dipped in asphalt), we then torch our base sheet onto the mat. Once completed, we stagger our cap sheet and then torch it onto the base sheet. Total thickness approx 1 cm!