A 1,742,400 sq. ft. manufacturing facility called us to come inspect their flat roofing system. They asked us to check for deterioration due to the age and present our findings to them. They also inquired about the cost of new skylights.
The first thing we noticed is that the facility roof was divided into over 20 sections. These sections were being reroofed over a period of years. The owners decided over 20 years ago that due to the size of the facility, they would do the roofing in sections. This strategy allows each section to have a lifespan in a different yearly quarter.
After our close visual inspection, we found the section was compromised of an asphalt and gravel built-up roof assembly. It was extremely dry, oxidized, and brittle. Photo-oxidation by the sun, in conjunction with extreme heat and cold, had broken down the waterproofing layer.
Our plan was to remove the old roof assembly down to the deck, removing areas of damaged metal decking. Then we would install a vapor barrier over the metal deck, followed by a new .060 PVC roofing membrane.
During pre-job walkthroughs, we determine what safety measures are needed. We use a system of trash chutes, safety rails, and tie-off equipment for all ladders at our job sites. For this job, we also decided to use interior tarps to protect the inventory, as this was a paramount concern.
Starting the Project
We started the project at the lowest point of the roof by removing the old gravel with a Roof Vac Machine. Once the gravel was removed we removed the old asphalt-based material. We did this by cutting the roof by hand and with a machine. As we progressed to the highest roof point, we tied everything off to ensure dust was kept to a minimum. It also kept the area watertight.
After exposing the metal deck we were able to determine what areas needed to be replaced. When the replacement was complete, we cleaned and primed the metal deck area to prepare for the vapor barrier installation.
Vapor Barrier Protection
Condensation may form when the interior building temperature rises. The heat and moisture are pushed to the ceiling and out of the roof into the insulation, often damaging the new roofing system. A Vapor Barrier between the roof deck and insulation is used to prevent this from occurring.
The new skylights were then installed. We also installed OSHA approved safety cages, used to prevent falling objects to enter the building. Expansion joints were used as tie-offs between the new section and older section.
Next, tapered insulation, tapered edge strip, and Drain Sumps were installed. They direct water flow towards the drains to help reduce ponding water.
We installed insulation in a staggered fashion to move the water away from the skylights and towards the drains. A Tapered Edge strip was installed at the expansion joint to direct water away from this tie off detail.
We also used a Drain Sump below the roofline along with the tapered insulation. This is more effective to help shed water and eliminate water ponding.
Conduit Markings and Counter Flashing
Once the insulation was complete, we marked the location of all the inside conduit lines on the insulation. This helped us not damage the conduit lines as we mechanically fastened the insulation to the roof deck.
Next, we installed counter flashing around the perimeter of all skylights, edges, and expansion joints. This is to prevent interruption of the PVC roofing membrane, allowing a monolithic roofing system.
Upon completion of the new roofing assembly, we used a large magnet to pick up any loose screws or metal shards. We then used forced air to gather and bag up any remaining debris. Everything was then removed from the project site – including trash chutes, ladders, and safety rails.
Inspections come next, by both the roofing manufacturer and Building Department Inspector. The roofing manufacturer checks that the system was installed per their specifications. The Building Department Inspector makes sure we are compliant with all local codes. Once both inspections were complete, we closed out the building permit. Then we could give the Building Owner their manufacturer warranty.
We hope you’ve enjoyed this behind the scenes look into our process of replacing a commercial roof. If you have any questions about replacing your commercial roof, please give us a call today. We will set up a free roof consultation and go over options with you.