Job Example of Copper Box Gutter Repair
What We Do
The most durable solution for box gutters, or built-in gutter, on a slate roof is copper lining. This is the more expensive option because of the material but mostly because of the time it takes to install copper lining.
This box gutter was leaking because the previous installers soldered the gutters around the roof together with no expansion joint. Copper gutters need room to expand and contract due to thermal movement over the seasons. The rule of thumb is every 30’ will need room for 1/4” of movement. In this case there was no room for thermal movement and the seams cracked allowing water to leak through the soffit.
Then to make matters worse a band aid repair of silicone was placed on top of the soldered seams which made it impossible for us to re-solder the gutter because of the impurities.
When we took off the old box gutter lining we found rotten decking. We replaced the decking with 1x6 boards and quickly lined the gutters with ice and water shield to protect them from the rain while we worked.
Next we measured the trough sides and calculated a slope towards the downspout at a 1/4” drop every 10’. We fabricated the copper box gutter pans on a sheet metal brake for a custom fit. Before installing the pans, we pre-tinned the back of the pans with solder so we could sweat the solder in-between the copper pans.
Next where the pans overlap we installed rivets in a zig zag fashion every 1” for added strength so the pans wont pull apart. Then, we soldered the pans together using 60/40 tin/lead solder and new metal flux. It is important in this stage to thourougly sweat the copper before stitching. If solder is treated like caulking it wont fuse the metal together.
Lastly, we drop outlets and end caps before putting the synthetic slate tiles back into place using slate hooks.