The weep hole was a gap left open on purpose. A small opening at the bottom of a brick wall where the mortar was omitted between two bricks. The gap was the size of a finger. The gap let the water out. The water that got behind the brick facade ran down the back of the brick and collected on the flashing at the bottom and the flashing directed the water to the weep hole and the weep hole let the water exit. The weep hole was the drain. The wall had a drain and nobody knew it was there.

Every third brick at the base course had a weep hole. Every third brick. The spacing was not random. The spacing gave the water enough exits that the water never had to travel more than sixteen inches to find a way out. Sixteen inches was the distance the water would travel before it pooled. Pooled water was damage. Moving water was drainage. The weep hole kept the water moving. The weep hole was a promise that the water would never stay long enough to cause trouble.

The weep hole was counterintuitive. The homeowner saw the gap and thought the mason forgot to fill it. The homeowner filled the weep hole with caulk. The caulk sealed the drain. The water that used to exit through the weep hole now stayed behind the brick. The water froze. The ice expanded. The ice pushed the brick off the wall. The homeowner who sealed the weep hole destroyed the wall by trying to fix what was not broken. The gap was the feature. The gap looked like a mistake. The gap was the most important gap in the wall.

The mason did not explain the weep hole. The mason left the gap and the gap was invisible from ten feet away and the mason moved on to the next course. The weep hole was not in the architectural drawings. The weep hole was in the mason knowledge. The mason knew that brick absorbs water and water needs to leave and the leaving requires an exit and the exit is the weep hole. The knowledge was in the trade. The trade passed the knowledge from mason to mason the way a song passes from singer to singer. Nobody wrote the weep hole down. Everybody who laid brick knew about it.

Modern walls use weep vents. Plastic inserts shaped like a brick that snap into the mortar joint and create a screened opening. The screen keeps the insects out. The plastic keeps the mortar from filling the hole. The weep vent is a manufactured solution to a problem that the mason solved with nothing. The mason solution was absence. Leave the mortar out. The weep vent solution is presence. Put a product in. The absence worked for three hundred years. The product works for ten. Absence is free and permanent. Presence costs money and expires.

See also: Pointing, Tuckpointing