Rooftop Equipment Curbs and Supports in Brockton, MA
The leak under a rooftop unit gets blamed on the roof. The roof is fine. The curb is the problem. Mechanical contractors set units, cut openings and leave the flashing to someone else. Years later the roofer is called to fix a leak that started the day the unit went in. Equipment curbs and supports are where a roof meets the building's machinery, and they are a frequent failure point.
Brockton, MA adds load to that detail. About 34 inches of snow a year piles against curbs. A record low of minus 19 degrees Fahrenheit shrinks sealant. Wind averaging 14.3 mph shakes units on their mounts. We treat each curb as a roof component, not a mechanical afterthought.
Check the Curb Corners and the Top Edge
A curb is a box that raises a unit above the roof surface. Membrane flashing runs up its sides and ends at a top termination. Failure starts at two places. Corners open where the membrane folds, and the top edge pulls loose where sealant dries.
We press on every curb. We look for gaps at corners, split flashing and rust on metal curbs. A unit that vibrates loosens the flashing over time. Water runs behind it and into the curb. From there it enters the building through the duct opening. Repair means cutting out the old flashing, cleaning the curb and installing new membrane with a proper termination. We seal the top, then test.
Gaskets and panel seals matter too. An access panel that does not close tight lets rain into the unit cabinet and down the duct. Duct penetrations through the curb need sealing on the inside. We check what we can reach and report what belongs to the mechanical trade. A flashing failure repair at the curb solves only the roof side of the leak, so we trace both.
Look Past the Unit to the Support
When a unit drips, owners call the HVAC contractor. Sometimes it is a condensate line. Often it is roof water entering at the curb and showing up inside the unit or below it. The two look alike. We check the curb and the drain line together.
Supports cause their own trouble. Pipe and conduit rest on blocks or sleepers. A block without a pad rubs through the membrane. A sleeper that is too low traps water. Supports that were set directly on the membrane without protection leave a worn spot under each point. We replace blocks with pads, raise sleepers and spread loads so no single point carries too much.
Condensate lines deserve a note. A line that drips onto the membrane in one spot wears a hole in it. Algae grows, the surface softens and the membrane thins. The fix is a line routed to a drain or a splash block, with a pad under it. It costs little and prevents a repair.
Check Height, Slope and Spacing
A curb works only if it stands high enough above the roof. Water ponds, snow drifts and ice builds. If the top of the flashing sits too low, water reaches it.
- Curb height above the finished roof surface
- Slope of the roof around the curb
- Crickets behind curbs on the uphill side
- Spacing between units and walls for access
- Support spacing for pipes and conduit
- Condensate drain routing away from the membrane
On a crowded roof with many units, there may be no space left for walk routes. Service crews then walk where they can. We lay walk pads on those routes and mark them on the roof plan.
We record each unit on a roof plan with its curb type, size, height and flashing condition. Later visits update the plan. After two or three visits, the plan shows which curbs fail first and why. A roof condition report turns that into a list an owner can budget against.
Brace Units for Wind and Snow
Wind lifts and slides equipment. Brockton is among the windiest cities in the country. Nor'easters add gusts in winter. A unit held only by its weight can shift, and a shifted unit breaks its curb flashing. Units need tie-downs sized for the wind load, and those tie-downs must not puncture the curb flashing.
Snow drifts around units and curbs. Drift loads add weight to supports and hide drains. After a storm, we check for displaced panels, bent condensate lines and ice build-up on exposed lines. Frozen condensate lines can back water into a unit or onto the membrane. Heat trace or rerouting solves that. We coordinate with the mechanical contractor, who handles the equipment itself.
Ice is the other winter risk. Meltwater runs off a unit, hits a cold curb and freezes. The ice sheet lifts flashing and cracks sealant. Curbs on the north side of a roof stay cold longest. We use materials rated for cold, and we avoid details that depend on adhesion alone.
Rebuild the Curb or Replace It
A sound curb with failed flashing needs new flashing. A rotted wood curb or a rusted metal curb needs replacing. A curb that is too low needs raising. Each repair has its own steps, and we price them separately.
When a unit is being replaced, the curb is the chance to fix everything. An adapter curb can match a new unit to an old opening. A new curb can raise the unit above drift height. We coordinate with the contractor, so the roof is open for the shortest time. For full re-flashing, the detail rules match skylight and penetration flashing. A bad curb can also be the leak behind an emergency roof repair call.
Pipe supports follow the same logic. A pipe on a rigid post must stay put while the roof moves under it. Adjustable supports with a pad and a base flashing let the roof and the pipe move apart without tearing. Gas lines and refrigerant lines have their own rules, and the mechanical trade handles those. We make sure the roof under them is protected and flashed.
Count the Units on a Large Roof
Distribution and retail roofs can carry many units. The Avon Industrial Park, with 127 firms on about 500 acres, is the sort of district where a manager may have rooftop equipment to track on several roofs. Every unit is a hole in the roof. Every hole needs a sound curb.
Waiting costs more than fixing. A leaking curb wets insulation, and wet insulation spreads. On a roof with dozens of units, a preventive maintenance plan that checks curbs twice a year keeps small flashing failures from becoming wet-board projects. Managers in Avon, Stoughton and Brockton can set that schedule across all their roofs.
Commercial Roofing Questions
Who is responsible for the curb flashing?
The roofer should flash it, and the mechanical contractor sets the unit. Problems start when the two do not coordinate. We flash curbs and work with the contractor.
Can a curb be raised after installation?
Yes. The unit is lifted, the curb is extended and the flashing is rebuilt. It needs the mechanical contractor and a short outage.
Why does my unit leak only in storms?
Wind-driven rain reaches gaps that normal rain does not. The leak is often at a curb corner or a loose panel.
Do you move or reset units?
We do not handle the equipment. We coordinate with the mechanical contractor, remove nothing live and rebuild the roof side after the unit is reset.
What are walk pads for?
They protect the membrane along routes where technicians walk. They cost little and prevent punctures and scuffing.