Installing a Brand New 2ply Mod Bit Flat Roof at a London, Ontario Residence

This week we were out in the North end of London, Ontario at a beautiful century home. This project is a bit unique, as normally we come out and just do one or two flat roof sections, this residential project has multiple flat roofs for us to replace:

  1. A flat roof over an interior living space
  2. Garage flat roof in the rear of the home
  3. A flat roof section in the back

All of these roofs were at different stages of their life capacity, and rather than coming back for one section at a time, the client wanted to go all out and get all flat roof sections replaced so they are all covered by our warranty.

Each section needed the same amount of work to be done, so we wanted to take a little more time to explain the process of how this all fits together.

First we clean off the roof, and ensure the condition of the roof is ok to roof over. Then we installed a new substrate to provide a secure and level foundation to build the roof on. Depending on the elevation, sometimes we use the substrate to create an angle to control the flow of water and avoid any pooling.

Then we prime the roof. The prime is more like a glue that activates back of the asphalt for the peel and stick membrane so it fixes onto the new substrate. It’s a roll on application with the same type of roller you could get at a paint store, it’s a single use roller. It’s a liquid that you roll on in a thin layer, then you let it flash (which activates the glue) for about 5-10 minutes then you can install the peel and stick membrane.

For the wall flashing detail, we kept them in place on this home as it gave our membrane a solid and strong substrate to adhere to.

Once the membrane is installed, we install metal drip edge flashing around the permitter which envelopes the base sheet so water ice and snow can’t get back up underneath the base sheet waterproof membrane. Then we prime the roof again, and then apply the cap sheet, which gets welded where it overlaps, which is what we call a salvage edge.

The project came out well, with the new metal that matches the existing metal and window colours, with the crisp new grey flat roof which will hold up for years to come and give the homeowner peace of mind. We love the way this project turns out. We certainly think a newly installed flat roof is a beautiful thing!