Phased Industrial Flat Roof Replacement in North York

Phased Replacement Roof for Industrial Site by Elite Roofing and Contractors Limited

Dorplex Logo

Phased Industrial Flat Roof Replacement

Dorplex Industries Limited

Building Address:

100 Norfinch Drive

North York, Ontario


The Ask

Our client, Dorplex Industries Limited in the North York area of Toronto, bought an industrial property in and around 2011. The 66,310 square foot roof was 40 years old and poorly maintained. When our client moved in, they found numerous active leaks that needed extensive repairs and partial replacement. From severe metal deck substrate corrosion to solving active leaks during extreme Canadian winters, Elite found innovative solutions to the various challenges with this phased industrial flat roof replacement.

The Approach

Sometimes, a complex industrial flat roofing project with a large budget calls for a phased approach. After discussing project requirements with our client, we broke the project down into three phases: (1) the production area, (2) the office, manufacturing, and assembly areas, and (3) additional manufacturing and assembly areas, raw materials storage, and shipping and receiving. Each phase, with its challenges and solutions, is described below.


100 Norfinch Dr- Elite Roofing, Toronto, Canada - Phased Industrial Flat Roof Replacement - North York
Aerial Image of the Dorplex Industries Limited Building from 1971


Phase 1—Production Area #1 (2012):

The client advised us that its priority was the production area, where it was installing a paint line complete with new make-up air equipment.  


Planning and Coordination Challenge:

Dorplex Industries wanted to prepare the roof area in their plant before the installation of a paint line complete with a new make up air unit.


The client requested us to have our licensed welder inspect and provide the necessary structural reinforcing for the new make up air unit. Because of additional live load on the building, we coordinated with a high-quality structural engineer to design the necessary supports. The welding work was completed and inspected, followed by our installing the new mechanical equipment working with the client’s HVAC contractor.


Phase 2—Production Area #2 and Office area (2016): 

We did a partial flat roof replacement, which required extensive work to repair the deck substrate. 


 Unforeseen Deck Substrate Challenge:

The section of the roof over the production area had numerous areas of deck corrosion that were not clearly visible in advance.  These were discovered once we removed the old roof to expose the deck substrate. We discussed the options for remedial repair with the client. 


We painted some of the lighter areas of deck corrosion with rust inhibiting paint. In more severely corroded areas we painted the deck substrate with rust inhibiting paint, installed a polyethylene separation sheet, and inlaid new metal deck substrate over top of the original deck substrate. The worst areas of corroded deck substrate were replaced.


Phase 3—Production Area #3 (2022): 

We protected the client’s work area and inventory from damage caused by multiple active leaks during severe winter snow and ice storms, prepared the area, and replaced the flat roof once the weather improved.


Winter Storm Challenge:

The extreme storms of January and February of 2022—with over 18” of snow and subsequent freeze/thaw cycles over next two months—triggered active leaks on the remaining 50-year old roof section. The storms and repeated freeze/thaw cycles prevented us from repairing the leaks until we could start the roof replacement. Meanwhile, the raw material inventory kept below it needed to remain dry. However, the client was reluctant to spend money repairing a roof that was to be scheduled for replacement within 90 days. 

Commercial Phased Industrial Roof Replacement - North York
Daylight is visible from inside the plant at areas of deck substrate corrosion and perforation.


Commercial Phased Flat Replacement Roof, North York, Ontario. This photo show rusted deck corrosion before the flat roof replacement.
Exposed rust perforated metal deck substrate.


As an ingenious stop-gap measure, our service plumber designed, fabricated, and installed water diverter tarps to shed water and direct them into floor drains. After February, we finally got to Phase 3, replacing the last portion of the roof that was 51-years old, double the lifespan of a typical roof!

Coordination Challenge:

The original roof was in very poor condition, with numerous leaks. However, the client was concerned about us creating additional problems as we began roof replacement work. 


We alleviated the client’s concern by minimizing traffic over the old roof area by strategically placing and storing materials. Our plan considered the location of the asphalt kettle, disposal bin, and pile of gravel on the ground.   

Commercial Phased Flat Replacement Roof, North York, Ontario
View inside the plant showing the water diverter tarps that were fabricated and installed.

Abandoned HVAC Equipment Challenge:

There were several pieces of abandoned HVAC equipment that the landlord elected to remove and dispose of.  

Solution: The client’s HVAC contractors disconnected the electrical and gas connections, plus any ductwork below the roof line. Our forces coordinated the hoisting and removal of the equipment off the roof using a boom truck, arranging for the disposal of the scrap and patching the deck substrate at voids with the new metal deck as an infill.


Future Ongoing Maintenance Work

Drainage Challenge: The flat deck substrate commonly used in the 1970s has no positive water drainage in the structure to the existing roof drains/rain water leaders. The resulting ponding water issues were localized and will require attention to avoid any deterioration of the roof membrane.

Solution: While not currently in the budget, we have recommended adding roof drains where required at a future date. When the client is ready, we will work on a solution that meets their budget. We installed drain sumps to improve the catchment area around existing roof drains during the roof replacement.  This assisted with positive drainage.  We also recommended a once per year maintenance inspection and tune up on the building as the section completed in Phase 1 is now over ten-years old.



Sometimes complex jobs are hindered by extreme factors, including unexpected active leaks and weather conditions. When a project extends into three phases, with long lag times in between, unpleasant surprises are not uncommon.

With positive client communication, a priority on safety, and ingenious solutions to unexpected problems, Elite succeed in protecting the client through the storms and providing a long-lasting roof that can withstand our tough Canadian winters.



Building Height: 20 Feet

Total Building Area: 66,310 Square Feet

  • Phase 1: 15,530 Square Feet
  • Phase 2: 22,900 Square Feet 
  • Phase 3: 27,880Square Feet


  • Base layer: 1.5” polyisocyanurate 
  • Cover board: 0.5” perlite 

Membrane Type: 

  • 1 ply #15 perforated organic felt paper 
  • 3 plies Type IV glass felt 

Ballast: ⅜” pea gravel embedded in a hot asphalt pour

Flashings: 2 plies SBS modified bitumen membrane

Metal Copings: Dark brown 26 gauge pre-painted steel


Contact Elite Roofing for your next roofing project!

Elite Roofing prides itself on quality workmanship and exceptional customer service. Here at Elite, we are more than just a roofing company, we are a family. We’re available 24/7 to answer all of your roofing questions. That’s the Elite Advantage.