Weep holes are the gaps left between some bricks in external masonry walls. They serve two important purposes:
Ventilation of the internal wall cavity: Without ventilation, mildew, dry rot and damp reduce the life of the internal wall studs and other building materials within the cavity. Inadequate ventilation is the main cause of ‘Leaky Building Syndrome’.
Drainage: Water that enters the cavity due to capillary action, condensation, damage, or accidental flooding needs to escape somewhere. In tropical and sub-tropical areas of Australia it is not unusual to see water flowing from the weep holes on the prevailing side of well constructed houses after a 'gully raker' or monsoonal storm.
Problems with Weep Holes
If weep holes are left unprotected they provide access to the wall cavity for rodents and insects. Swarming bees and European wasps love creating nests in cavities. Field mice make a track through the weep holes looking for warmth. Snakes, cockroaches and spiders find refuge, and food, in the cavity. Downlights, extractor fans and holes for plumbing or electronics become the internal entry point for these unwelcome visitors.
In desperation many occupants resort to blocking weep holes with any number of materials such as silicon sealants, rolled up paper, plastic, scourer pads and steel wool. Unfortunately some manufactured weep hole covers, guards and barriers have also been designed with holes too small to allow adequate ventilation. Weepa's Pest Stoppa and Protector Weep Hole Screen can be easily fitted to keep these pests out whilst maintaining airflow.
'Solutions' that obstruct air-flow to the cavity cause moisture problems. The resulting ‘Leaky Building Syndrome’ can be difficult and very costly to fix later.
Weep Holes and Bushfires
Weep holes provide access for embers during bushfires sometimes with devastating consequences. Sparks enter the wall and roof cavity and the house ignites ‘from the inside’. It’s common to hear stories about firefighters saving houses in the direct path of a bushfire only to find houses further back suddenly bursting into flames.
In Australia the Building Code for bushfire-prone areas (AS3959:2009) has specific requirements for ember screening in weep holes in all houses built in areas of declared bushfire risk including BAL-12.5, BAL-19, BAL-29, BAL-40, BAL-FZ. Our Bushfire Products include metal mesh screens, which prevent the entry of embers and keep the cavity safe.