London By-law CP-24, s. 2.8(2) — Property Standards By-law

Despite section 4.3, in order to minimize the potential of deterioration of a building, where the exterior doors, windows or other openings are missing, broken, improperly fitted, unsecure or in disrepair, or where the property remains vacant for a period of 30 days or more, the property shall be boarded in compliance with the following requirements:

• a) all boards used in the boarding shall be installed from the exterior and shall be properly fitted in a watertight manner to fit within the side jambs, head jamb and the exterior bottom sill of the door or window so that any exterior trim remains uncovered and undamaged by the boarding;
• b) all boards should be at least 12.7mm (0.5 in.) weatherproofed sheet plywood secured with nails or screws at least 50 millimetres (2 inches) in length and be installed at appropriate intervals on centre;
• c) all boards shall be painted or otherwise treated so that the colour blends with the exterior of the building or structure.