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B6.2 Animals: rats, mice, snakes and birds

Rats, mice and other vermin such as snakes and birds can spoil food, contaminate surfaces in the house, and pollute the water in the rainwater tank or main water supply. As discussed in A1.3 ‘Cabling and wiring’ mice and rats can also cause electrical faults by chewing the protection from cables, particularly in ceiling spaces above bayonet light fittings. Snakes can also lead to direct injuries.

Rats, mice and other vermin can gain access to houses through ventilation panels, cracks in walls, edges of roofs, wall, floor, door and window junctions, or the access points for electrical wiring and plumbing. They may also live and nest in framed walls, sub-floor spaces, ceiling spaces, under stoves, and around hot water systems.

Before commencing design, talk to the residents and housing manager about local vermin and identify appropriate design strategies.

Data from over 7,500 houses show that mice and rats are still a house design issue with 46% of houses reporting the presence of mice or rats during the year (32% of houses) or evidence being found of their presence at the time of survey (14% of houses).  Many household residents (61% of houses) reported no ‘other pests’. ‘Other pests’ are defined as white tail spiders, redback spiders, any type of snake, wild camels, pigs, horses, crocodiles, rabbits, donkeys or ticks. These houses may have had dogs, cats, mice, rats, flies, mosquitoes, ants and cockroaches.

Data shows that most houses (71 per cent) had some type of framed wall construction that without well designed, specified and constructed linings could provide habitat for rats, mice, snakes and other vermin. There was a significant decrease since 2006 in the number of houses with holes or cracks in inside walls, a 4% reduction, and outside walls, a 5% reduction. This reduces the risk of vermin entry, nesting and damage.

The efficient disposal of food scraps and rubbish from the house, particularly the kitchen, can reduce the presence of pests. Only 14% of houses surveyed had a working rubbish bin in or near the kitchen.

Real world examples of problems

Design and Specification

Ensure

  • B6.2 .2.

    walls, eaves and ceiling linings use materials that can resist accidental damage, which could create entry points for vermin

  • B6.2 .3.

    penetrations through bond beams, used with block work walls, for electrical wiring are sealed against vermin entry into block work cores and electrical wiring

  • B6.2 .4.

    any penetrations in walls or floors for drains, electrical cabling and water supply piping are sealed with a solid material to prevent entry by vermin

  • B6.2 .5.

    corrugated metal walls are sealed around the edges using a metal barrier made from similar material to prevent entry by mice and other vermin

  • B6.2 .6.

    ventilation openings are screened to prevent entry by vermin

  • B6.2 .7.

    that any ceiling mounted light fitting, that can be fitted with a heat producing bulb or globe, only be installed if a protective cover over the wiring point of connection in the ceiling space is fitted to avoid mice nesting on the warm fitting and attacking wiring

  • B6.2 .8.

    rainwater tank openings, inlets and overflows, are screened to prevent entry by vermin that drown and pollute the stored water

  • B6.2 .9.

    when using polyethylene (PE) or poly vinyl chloride (PVC) water piping that the pipe is well protected from vermin attack

  • B6.2 .10.

    doors stops are fitted to prevent door handles making holes in walls, which could create entry points for vermin.

Consider

  • using conduits for electrical cables in ceiling spaces
  • using strong internal wall materials up to at least 1800mm from the floor to prevent accidental damage, such as moving furniture or door handles damaging walls, that might enable access by rats, mice and other vermin
  • designing vermin proof pantries or food storage cupboards
  • selecting stoves with a vermin proof shell or vermin proofing kit
  • avoiding the use of standard bayonet-type light fittings on the ceiling to prevent mice nesting in the ceiling space above the fitting
  • specifying solid seals around plumbing, drains and electrical conduits
  • fitting weather strips on all external doors
  • avoiding insulated sandwich panel construction for walls, where bottom wall plates and panel joining strips are subject to water and physical damage, as the insulated core can then harbour rats, mice and other vermin.
  • the use of insulated sandwich panel ceiling systems, with well sealed edges, to prevent mice breeding places in ceilings and provide a good clear working surface for maintenance contractors.

Real world examples of Solutions

    Quality control

    • wall materials and floor to wall detailing inside and outside the house for gaps and voids that may allow rodent entry
      COMPLETED DESIGN & SPECIFICATION
      AT HANDOVER
      FINAL COMPLETION
    • any roof vents, gable end vents, evaporative cooling system ducts, eaves linings and wall to ceiling junctions for rodent entry points
      COMPLETED DESIGN & SPECIFICATION
      AT HANDOVER
      FINAL COMPLETION
    • door stops have been fitted to prevent wall damage from door handles
      COMPLETED DESIGN & SPECIFICATION
      AT HANDOVER
      FINAL COMPLETION
    • weather strips are fitted on external doors, if specified
      COMPLETED DESIGN & SPECIFICATION
      AT HANDOVER
      FINAL COMPLETION
      TRADE TEST
    • metal flashings or cover strips are properly fixed on steel clad houses.
      COMPLETED DESIGN & SPECIFICATION
      DURING CONSTRUCTION
      AT HANDOVER
      FINAL COMPLETION

    Maintenance

    As part of cyclical maintenance:

    • if there is an observed pest problem, establish a pest reduction program carried out by a licensed contractor
      Pest Controller, Housing Management
      6 Months
    • repair holes, cracks or gaps that allow rodent entry
      Carpenter, Local Maintenance Team
      6 Months
    • cut back tree branches that are near to, or touching, the house that may provide vermin entry.
      Local Maintenance Team, Housing Management
      12 Months
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