1. Article Body
Multifamily roofs fail at the joins. Almost every recurring leak in an apartment building traces to a place where one thing meets another rather than to the middle of a roof area.
Transitions between roof types
Where a low slope roof meets a steep slope section, where a mansard meets a flat deck, where an addition meets the original structure. Two systems, two movement rates, one junction.
These details are hard to build and easy to build badly, and they are the single most common source of persistent multifamily leaks.
Balcony and walkway thresholds
A balcony is a roof over whatever sits below it, and the threshold at the door is the lowest point in the assembly.
Water backs up at a blocked drain, rises above the threshold and enters the unit. Residents describe it as a balcony problem. It is a drainage and flashing problem.
Stair tower and small isolated roofs
Every building has small roof areas nobody walks: stair towers, elevator overruns, trash enclosures, entry canopies.
They have their own drains, their own flashings and their own failures, and they are routinely excluded from both inspections and quotes because they are not the main roof.
Plumbing vent penetrations
Multifamily carries far more penetrations per square foot than comparable commercial buildings, because every unit has a stack.
Pipe boots split under ultraviolet exposure on a predictable cycle. On a building with sixty vents, a five percent failure rate is three active leaks.
Mechanical screens and equipment bases
Screen walls are fastened through the roof. Condenser units sit on sleepers or curbs. Both create penetrations and both are usually installed by trades other than the roofer.
Scuppers and internal drains
Small roof areas often drain through a single scupper. One blockage floods the whole area.
Internal drains in older multifamily buildings frequently pass through occupied space, so a drain failure delivers water into a unit rather than onto the roof.
Foot traffic
Roofs with rooftop equipment get walked by HVAC technicians, cable installers and satellite crews. Membrane damage from traffic concentrates along the informal path between the hatch and the equipment.
Walkway pads cost very little and prevent it.
The maintenance gap
The underlying cause behind most of the above is that nobody owns the roof operationally. Maintenance falls between the onsite manager, the management company and the association board, and the result is that nothing is inspected until something leaks.
Name one person, set two inspections a year, and put the small roofs in the scope in writing.
