What happened

After the first significant storm, water appeared above the head of the new bifold doors on a rear extension. The cavity tray and weep vents above the lintel had been omitted.

How it was discovered

Rainwater ingress, then borescope inspection through a small opening.

The consequences

Brickwork opened up, cavity tray retrofitted, weep vents installed, brickwork rebuilt. Internal redecoration. Two weeks of work — most of it cosmetic.

What homeowners can learn

The detail above an opening is more important than the lintel itself. Photograph cavity trays at construction.