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How to Repair or Replace your own Flat Roof

This week we were at a beautiful heritage home, and we wanted to take some time to show you something a little different at Legacy Flat Roofs. We thought we would show you how you can install a new flat roof at your home.

Many times you’ve seen us install a roof over the top of the existing flat roof because the condition of the roof was good enough to use, as there hadn’t been any perforations in the flat roof, or any water leaks or dampness, so it was safe to go over once the roof has been inspected.

In this case the roof has been completely removed down to the wooden decking. Even some of the flat roof decking has been water logged and was rotting, and needed to be removed.

Because this is a unique heritage home, we want to make sure no water is sitting on the roof. It’s a canopy so the client walks into the house underneath this structure, which you can see when we are at ground level. We are trying to keep the water from going over the edges of the canopy onto the entrances, where water can freeze, or just get the client wet as they come into the home. The client didn’t want an eavestrough, to keep in line with the look of the home.

We always begin with plywood decking installed over the top to provide a solid foundation. Then we add a sopraboard, and what we plan to do with that is create a taper, to not allow any water to pool, but to be forced off the roof to an area where there is no entrance to the canopy. This is Canada, so in January, February, March, there is a lot of snow, ice and water buildup, so controlling the flow of water off the flat roof is important.

One the sopraboard has been installed, a peel and sick base sheet is added, then a metal drip edge is installed over the base sheet, and down the outside of the fascia board. The drip edge has a 45 degree kick on it, to get the water away from the walls and surfaces.

From there we prime the base sheet, and put the membrane down on top of that, with a slight overlap of the edges to create a sealed seam. Then we heat weld the seam to create a great water tight seal.

Then we put metal flashing around the edges along the brick and masonry. This was a tricky area, as we had to be very careful. Because the home is a heritage home, you should avoid trying to tapcon or screw anything into the brick, because the brick is very old and brittle, and can actually explode and be ruined. And it is a very difficult task to replace century home brick, so we used construction adhesive to fix the metal onto the brick, and we used white caulking to seal the edges of the metal.