We have these roof valleys, and over the years, they developed rust on the surface due to the dirt and leaves remaining within the valleys. There were no holes in the valleys, and our friend, who is a roofing contractor, suggested painting them instead of a full replacement. Thanks to a previous post, from @EricL and @RipVanCutter, we were able to paint all the valleys. They should last another couple of years before we need to replace them.
Steps
Step 1
Cleaned Surface
Rust removal
The first step is to clean and remove all the surface rust from the valley. Preparation of the surface is critical for the waterproofing and paint to come afterwards. We used the wired brush to remove as much rust as possible. For concentrated rust areas, we used a wired disc attached to the impact.
Tip: Wear some think garden gloves as the tile edges are sharp.
Step 2
Rust converter will cause the affected rust surface to turn black
The next step is to inactivate the rust process. Wear gloves and eyewear when applying the rust converter solution. Using a paintbrush, apply to only the rusted area. If you get some on the bare metal, wipe it off using a damp cloth. Leave to dry for 24 to 48 hrs. The rusted area should turn black after drying.
Step 3
Applying the waterproof paint
The next part involves brushing on the waterproofer agent using a paintbrush. We applied two coats to all the valleys. I would suggest the 2L size as we still had over 50%.
Tip: It was impossible to keep the valley clean during the application. Due to the wind dust and other matter would keep falling into the valleys. Brush off the dirt between each coat.
Step 4
Before application
Waterproofing step
Final two-three coats
In the final step, we applied three coats of the exterior paint. It was more affordable to paint the valleys than to replace all five valleys we had. It took about 2-4 days, and the hardest and longest step was the surface preparation. Once that was done, the other steps were much easier to complete.
