Commercial Roofing
Ice on the underside of a freezer building's roof deck is a roof finding, even though it forms inside, because it means moisture has reached a cold surface and stayed there. Food processing, logistics and warehousing appear among the employers Edinburg, TX lists, and a building that holds product cold belongs to that kind of work. A roof over a freezer or cooler carries a temperature difference that most roofs never see: a warm membrane in the Valley sun above insulation and a deck held far below freezing. Water that gets into that assembly does not just leak, it freezes, expands and stays.
We begin by tracing the moisture path, because a stain below can come from a roof opening, from vapor moving through the assembly or from a refrigeration line. A photo record tied to a roof drawing and readings from inside the building separate those causes.
In a normal roof, wet insulation can dry slowly in both directions. Above a freezer, the cold side pulls moisture inward and the water freezes in place. Frost and ice build up in the insulation, and the insulation loses value as it fills with ice. The deck can corrode, the underside of the roof can drip when the ice melts during a defrost or a power interruption, and the refrigeration load goes up.
We look for frost on the underside of the deck, ice at penetrations, stained or sagging insulation and unusual refrigeration load, along with the usual roof signs. On the roof, we check the membrane and flashings, then the vapor retarder and air barrier details where the roof meets the walls. A small hole in the membrane above a freezer can feed ice for months before it shows. A moisture survey helps find where the insulation has taken on water.
Liquid water enters through openings: split seams, failed flashings, damaged membrane and clogged drains. Vapor enters through gaps in the air and vapor barrier: penetrations through the deck, wall-to-roof joints, door frames and sealant failures. In a cold storage building, both matter. Warm outdoor air that leaks into the assembly meets a cold surface and condenses.
Penetrations are the main places. Refrigeration lines, conduit, ducts and structural members cross the roof assembly, and each crossing has to be sealed on the cold side and flashed on the weather side. When a seal fails at the bottom, warm air flows up the opening and freezes in the insulation. When the flashing fails at the top, rain follows the same opening down. We inspect from both sides where we can and record each penetration with a photograph, a location and a condition. The penetration flashing repair then addresses the weather side, and the interior seal is coordinated with the refrigeration contractor.
A roof over refrigerated space typically uses thick insulation, a vapor retarder placed to suit the temperature difference and a membrane that can accept the conditions at the surface. Design details vary with the temperature of the room, and the right sequence of layers is a design question for the building's engineer. What an inspection can confirm is what is there, how it is holding and where it has moved.
We record the insulation type and thickness if known, any signs of settlement or compression, the condition of the cover board and the type of membrane. Thick insulation means taller curbs and flashings, and heavier loads at edges. When we find wet or iced insulation, it is removed back to dry, sound material, and the vapor retarder is repaired or replaced before new insulation goes in. The cost drivers are the thickness of the insulation, the area that is wet and the need to coordinate with refrigeration. An insulation and cover board scope is written with those factors in view.
May through October is the Valley's heat-safety season, and a dark roof surface runs hot through those months, and the temperature difference between the roof surface and the freezer below is large. That difference drives heat and vapor through any gap, and it works on seams and flashings as the membrane expands and contracts.
Reflective surfaces reduce the heat load on the membrane and on the refrigeration system, and a cool roof installation may be part of a replacement or restoration plan for a cold storage building. The other seasonal factor is tropical weather: gusts from Dolly crossed Hidalgo County, and Hanna left wind and street flooding in Edinburg that July of 2020. After a storm we check edges, flashings and penetrations, since a small opening above a freezer has outsized consequences.
The boundary follows the wet or iced insulation and the damaged vapor retarder. A membrane patch over iced insulation is a temporary measure at best, since the ice will melt and refreeze under it. The repair has to remove the wet material, restore the insulation and the vapor barrier and then close the membrane.
We plan these repairs in stages, because opening a freezer roof exposes the cold deck to warm air. Each section is opened, repaired and sealed on the same day, and the work is coordinated with the refrigeration contractor and the facility director. For large wet areas, a phased replacement is priced next to a series of repairs. The evidence for each route, meaning moisture readings, core samples and photographs, is placed side by side so the decision is based on the roof's condition.
A freezer cannot be shut down for a roof job without risk to the product. We plan so the cold side stays closed: the roof is opened in small sections, the deck is covered immediately and the work window is short. Interior access for the refrigeration contractor is scheduled so that doors are open as briefly as possible. Before the first section is opened, we agree on a stop condition: if the forecast changes, if the deck is colder or wetter than expected or if the refrigeration contractor reports a rising load, the crew closes the opening and the plan is revised in writing.
We also coordinate dock schedules, truck lanes and equipment shutdowns, and we keep tarps and temporary seals on the roof during the storm season, which runs June through October. Nearby owners in Pharr or the McAllen area can bring several buildings to the same planning visit. The related building type distribution center roofing shares the dock and perimeter concerns, and warehouse roofing shares the deck and drainage questions.
The water freezes in the insulation and stays, so the damage builds quietly. By the time it shows inside, a large area may be affected.
Rarely. Iced insulation thaws and refreezes under the patch, so the wet material is removed and the vapor retarder restored.
Sometimes both. We inspect the weather side and, where access allows, the cold side, then trace where moisture entered.
We open small sections, cover the deck at once and coordinate door openings with the refrigeration contractor.
The 2018 building and energy codes the city adopted set the baseline, and on a freezer roof the insulation thickness in the scope is checked against them with the building department before pricing.