Why Weep Holes Are Important

When Twinspectors undertake a Building Inspection one of the items we always look at is weep holes.

Weep holes are the small gap left between bricks or blocks in external walls. These small gaps located at the bottom of the walls and their sole purpose is ventilation and drainage. During the Building Inspection we confirm they are of sufficient size to allow airflow or water flow.

In modern brick veneer homes, it is vitally important that the internal wall studs be well ventilated and drained to reduce the opportunity of mildew, wet or dry rot and damp as these reduce the life of the building. These weep holes are an essential part of the drainage allowing water and condensation to escape, ideally without allowing water to enter.


Obstructed Weep Holes

These weep holes allowed ventilation keeping the internal components dry. During a Building Inspection we tried to confirm the location of the weep holes. It Is vitally important they must be above the waterproof membrane and have proper flashing.

During periods of driving rain, water penetrates brick walls as the water enters through the wall it passes down the back and when the weep holes are present and open the water escapes back outside this water gaining entry into the cavity can be visible if you pull back the carpet and may be caused by the driving rain or gutters overflowing all water pooling against the exterior of the house. A Building Inspection is not normally invasive and hence we cannot pull back the carpet to inspect for water entry, though the use of Thermal Cameras and Moisture Metre may indicate water entry during a building inspection.

Some people blame this water ingress on the weep holes and block them generally it is not the weep hole it is to brick itself that causes the water entry. By blocking the weep, I’ll you have defeated the purpose of allowing the water to escape; generally, the weep holes are approximately 1 to 2 inches below the level of the concrete slab or flooring.

Though weep holes may look open they can be blocked or clogged for a number of reasons. The check to see if your weep holes are entirely open insert a piece of wire the width of the brick +25 mm. Sometimes with the rendering of houses, the renderer does not correctly clear the weep holes. Or even worse completely blocks the weep holes with render. The render should be cleared away, ensuring that there are proper ventilation and no damming of water inside. As a Building Inspection is a visual inspection only we can report on only what we locate.

It is not unusual during a Building Inspection we find leaves and other detritus has blocked the weep holes restricting the flow of air and sometimes the outflow of water these should be cleaned out.

Sometimes water gains entry because of rising water levels during times of rain this is best remedied by the installations of new gutters if required additional day on pipes or the installation of drains and contouring of water flow in the yard.

The adding of additional topsoil is and building up around the outside is not recommended as this creates a moisture problem in itself and does not allow adequate ventilation and possibly enabling hidden termite or other pest entry.