Jan 26 insulating and plasterboarding the garage door house wall main corner unboarded Insulating And Plasterboarding The Garage Door Dad and I worked on insulating and boarding the garage tonight. I had ordered some 50mm celotex boards to insulate the walls. We then plasterboarded over the top. I silicon sealed the gaps in the garage door and then insulated that too. insulating and plasterboarding the garage door