4. (1) This section applies to, (a) every room that is used for the housing of animals in a research facility or supply facility or for surgical, experimental or testing procedures involving animals; and (b) every room that is used for storing feed, bedding or waste or for the preparation of food in a research facility or supply facility.  R.R.O. 1990, Reg. 24, s. 4 (1). (2) Floors shall be, (a) soundly constructed of hard, durable material; (b) impervious to water; (c) constructed of a material that may be readily sanitized; and (d) maintained in a good state of repair, free from cracks, holes and other damage.  R.R.O. 1990, Reg. 24, s. 4 (2). (3) Where there are floor drains, (a) a floor drain and any trench installed in connection therewith that is used for waste disposal shall be flushed at such intervals as may be necessary to prevent any accumulation of waste that might impair the health or welfare of any animal in the room; (b) the floor shall be so constructed and maintained that surface liquids thereon will drain into the drain; and (c) the operator of a research facility or supply facility shall cause the drains to be examined as often as is necessary to ensure that they are functioning properly, have an adequate water seal and are not harbouring vermin.  R.R.O. 1990, Reg. 24, s. 4 (3). (4) Walls shall be, (a) soundly constructed of hard, durable material; (b) impervious to water to a height adequate for sanitary maintenance; (c) constructed of a material that may be readily sanitized; and (d) maintained in a good state of repair free from cracks, holes and other damage.  R.R.O. 1990, Reg. 24, s. 4 (4). (5) Where there is a door, (a) every frame or moulding around the door opening shall be so constructed and maintained that it has no space or spaces capable of harbouring vermin; and (b) the door shall be maintained in a good state of repair free from cracks, holes and other damage.  R.R.O. 1990, Reg. 24, s. 4 (5). (6) Where it is not practicable to sanitize any equipment that is in the room unless it is removed from the room, the opening of at least one door in the room shall be of sufficient size to permit the removal of the equipment from the room.  R.R.O. 1990, Reg. 24, s. 4 (6). (7) Where there is a window, (a) every frame or moulding around the window opening shall be so constructed and maintained that it has no space or spaces capable of harbouring vermin; (b) means shall be provided to prevent the effects of direct sunlight through the window; (c) the window shall be so constructed and maintained as to prevent the entrance of vermin through the window; and (d) the window shall be maintained in a good state of repair free from cracks, holes and other damage.  R.R.O. 1990, Reg. 24, s. 4 (7). (8) Roofs and ceilings shall be, (a) soundly constructed; and (b) maintained in a good state of repair free from cracks, holes and other damage.  R.R.O. 1990, Reg. 24, s. 4 (8). (9) Light fixtures shall be so constructed and maintained as to be readily sanitized.  R.R.O. 1990, Reg. 24, s. 4 (9). (10) Where any pipe, drain, conduit or other service facility is installed through any floor, wall or ceiling, the place where the pipe, drain, conduit or other service facility enters or leaves the room shall be so sealed as to prevent the entrance of vermin into the room.  R.R.O. 1990, Reg. 24, s. 4 (10). (11) Alleyways and service aisles between cages or pens shall be of sufficient width to permit the safe and efficient movement of persons and equipment and shall not be used for storage or accumulation of materials or equipment of any kind.  R.R.O. 1990, Reg. 24, s. 4 (11). (12) Every room in a research facility or supply facility shall be maintained in a clean condition.  R.R.O. 1990, Reg. 24, s. 4 (12). (13) The operator of every research facility or supply facility shall take all reasonable steps to prevent the spread of and to destroy vermin and invertebrates that may be harmful to the health, comfort or welfare of any animal in the research facility or supply facility except only that such steps need not be taken to the extent that the presence of such vermin or invertebrates forms a necessary element in any research.  R.R.O. 1990, Reg. 24, s. 4 (13).