It was a bright sunny morning in Queensland. The Allison family was getting ready for a regular day at work. Grandpa Allison suddenly noticed a gap in between two bricks. Worried about an insect infestation, Grandpa instantly filled it up with some mud and a lot of dirt from the lawn. He inspected for hollow spaces letting in insects. Satisfied that there are none left, he finally got up to go. Moving on in the same line, he noticed a second one; and then few more of such holes.
Ambivalent on what exactly he is supposed to do, he went and consulted Grandma Allison. Young Sue overheard them and decided to put forth a question at a masonry forum. They redirected her to their Weep Holes page. What they discovered was both amazing and astounding. Though this is a fictitious story, It’s quite common for a Queensland family to find holes in their homes’ external walls.
What is a Weep Hole?
The weep hole is a small opening allowing ventilation and water to drain from a wall cavity. The Australian Building Code states: “Australian Standards 3700 – 2011 Section 4.7.2: Weep holes shall be provided wherever it is necessary to drain moisture from or through masonry construction. Where flashings are incorporated in the masonry, weep holes shall be provided in the masonry course immediately above the flashing, at centers not exceeding 1200mm.”
Why are Weep Holes Important?
- They provide ventilation to the wall cavities, preventing dampness, dry rot and mildew from destroying internal components of your home.
- Weep holes also help a drainage system to allow in water, flooding and condensation to escape the wall cavity.
Can They Become Problematic?
Just the other day, there was a report of a snake slithering in through the weep hole. The terrified lady called us up, thinking we could help. Unfortunately we are not herpetologists. We can though forewarn you of a few other issues that can arise out of weep holes.
Weep holes are usually equivalent to that of a mini-size welcome mat. They are large enough to allow mice, roaches and other pests inside the house. With weep holes, there is nothing standing in the way of critters entering your home.
Another modern day disadvantage of weep holes is that they lack adequate ventilation. Modern homes are built air-tight. In the past, moisture was allowed to freely move from the interior to the exterior of the house and vice-versa. Modern homes have lost this ability and the moisture that enters through the outer masonry wall can actually get trapped in the wall.
As mortar is squeezed out from successive courses of bricks, droppings can fall behind the wall and build up. Signs of termite activity might also be noticed, if looked deep into weep holes.
Should I Cover up All Weep Holes?
Australian Standards 3700-2011 Section 4.7.2 Weep Holes
Weep holes shall be provided wherever it is necessary to drain moisture from or through masonry construction. Where flashings are incorporated in the masonry, weep holes shall be provided in the masonry course immediately above the flashing, at centers not exceeding 1200 mm.
Weep holes must be kept visible at all times to prevent the entry of insects. Property owners have to be careful to clear off all obstructions like foliage, mulch, stones, dirt and timber for at least 75mm below the weep holes. Inspections of all weep holes must be undertaken on a regular basis to check for blockages and signs of termite entry.