Drain Sumps, Scupper Boxes and Crickets
Water has to leave a low-slope roof by a path that works on its worst day. We cut the sump so the membrane drops into it without a fold, set a clamping ring that grips evenly, and size the strainer so a handful of leaves cannot block it. At the parapet, a scupper box is formed from sheet metal with soldered corners and set into the wall with counterflashing that laps over the base flashing. Behind each drain or scupper we build a cricket, a small sloped saddle of tapered insulation, so water is steered toward the opening rather than sitting beside it.
Done well, roof drains and scuppers need only a seasonal cleaning. Done poorly, they hold water against a seam for months. We mark on a plain drawing where the water goes, so the facilities team knows what to clear and when.
Hand-Formed Metal Where the Roof Meets Masonry
Wherever a membrane roof meets a masonry wall, the sheet metal decides how long the junction lasts. The coping is lapped and hemmed rather than butted, the cleats are fastened at the spacing the metal needs, and the counterflashing is set into a clean reglet cut in the mortar joint. These are hand-formed pieces, and a corner built from a flat pattern fits better than a corner bought off the shelf. If a building here has masonry parapets, we examine the mortar and the reglet before we take a quote any further, because a roof cannot outlast the wall it is attached to.
For longer runs, edge metal and coping work includes expansion joints that allow for the daily swing between a cool night and a hot afternoon. Without them the metal pulls at its fasteners until the joint opens. The fit and finish matter most at those points, and a careful crew spends more time on them than on any field of membrane.
Heat, Embers and the Cool Roof Rule
Thermal cycling works every seam and sealant joint on an exposed roof. We inspect the surface and details directly before selecting a reflective system or recommending repairs. Under California's Energy Code, a new low-slope commercial roof can meet the cool roof rule with an SRI of 75, or with 0.63 reflectance once aged plus 0.75 emittance, and a reroof that covers over 2,000 square feet, or over half the roof if that is smaller, falls under it too. On an older roof, years of that sun show up as heat and UV damage: chalking, blistering and brittle edges that tear when touched.
The Eaton Fire in January 2025 is the other reference point. Before it started, the forecast was for sustained Santa Ana wind in the 30 to 50 mph range and gusts of 60 to 80 mph over a wide area, and wind like that lifts embers and drives them into vents and gutters. We check which fire hazard zone applies to an address before we choose materials, because a Class A assembly is a requirement in the Very High zones and a sensible target beside them.
Condition Records and What Drives Cost
Roof cost on an institutional building is set by access, sequence and protection of the contents, more than by the membrane itself. A crane lift over a garden, tarped staging above an exhibition room and temporary drains all add time. We say so at the start and price each in the written report, so an owner can compare a full replacement with a staged repair. A roof condition report records photographs, moisture readings and remaining service life, and it becomes the file a board or trustee can read when the budget comes up. Owners who also hold buildings in San Gabriel or South Pasadena can have all of those roofs reported the same way.
Preventive work is the quieter half of the plan. A spring and fall visit to clear debris, check seams and re-seal the small gaps is how preventive roof maintenance keeps a good roof good. It is also the least expensive way to avoid a call at midnight after a storm, and our emergency response runs all night, every day of the year, when that call comes anyway.
Commercial Roofing Questions
What makes a roof over stored collections different from an office roof?
Tolerance. An office can live with a stained tile for a week, but a stack room cannot. We lean on moisture mapping, tighter sealing at every lap, and drainage details that clear quickly. The repair priority is the quiet leak, not the dramatic one.
How do tree debris and garden planting change the way a roof is maintained?
They fill the drains. Leaves, seed pods and grit collect in sumps and scupper boxes and keep water on the membrane long after the rain has stopped. The routine becomes frequent: check after leaf drop, check after the first storm, and trim any branch that rests on the roof.
Can a roof be repaired without disturbing what is stored underneath?
Often it can. Work from the top side is staged in small sections, each one sealed watertight at the end of the shift, and we protect the interior path under the area with tarped decking if needed. Noise, dust and vibration are discussed with the building manager before the first day.
Does the January 2025 fire change what a new commercial roof should include?
For addresses inside a Very High zone, yes: a Class A assembly, ember-resistant vents and gutter debris protection are required. Outside the zone these are choices an owner can still make. We check the address against the state map and report the finding before a bid is written.
Who decides when a coating is enough and when a roof needs full replacement?
The moisture readings do. Where the board beneath the old sheet reads dry and the sheet is still bonded, a coating or recover can extend life. If readings show saturation across a wide area, replacement is the right answer, and we show the data so the owner sees why.
