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Where should aluminum capping stop at the siding edge?
How should aluminum window capping meet the siding without covering an existing drainage path or making the edge difficult to inspect? The right detail may depend on whether the trim is recessed or nearly flush, but I don’t want to assume a bead of caulk is the answer. What clearance or edge detail lets water shed while keeping the window’s existing flashing and drainage functional?
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The key is to keep the cap clear of the window’s actual drainage outlet, not to use one standard setback for every window. With recessed trim, the cap can often return to the siding edge; with nearly flush trim, the termination may need a different profile. In either case, don’t bridge a weep or drainage opening with caulk. First identify where water exits and the path it takes, then leave that route open and visible.