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Discussion Starter · #1 ·
I am builder for an upcoming residential job that will have box gutters with concealed (in the exterior wall) leaders to nickel bronze decorative outlets letting out at the bottom of the wall. Box gutters and interior leaders are a detail I have not done before and while I find a number of details for the box gutter, I cannot find a detail for the whole assembly.

I am in climate zone 4, so we get freezing but not like New England. The house will be tightly sealed with closed cell foam and I'm confident that ice dams will not be an issue.

Essentially, I am concerned about clogging & damage over time (decades) of the leaders in the wall and my questions are

(1) what is the best choice of materials. Copper for the box, flashings, and downspout allows it to be soldiered and then the downspout can let into schedule 40 PVC pipe?

(2) The roofs are broken up by dormers and a downspout will be needed between each, so I will have more downspouts then the volume calls for. For instance, one typical roof is 993 ft2 has 2 dormers and is therefore served by 3 downspouts.

So I am thinking of having the inlet at the gutter be 3" going into a 4" leader which will make it hard for the leader to get sticks & leaves that clog even if the screen is missing and the gutters are not maintained.

Good idea or am I better off just having straight 4" all the way?

(3) if I detail it correctly does it still benefit from an electric deice cable?
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