Making a box gutter

[swidders]

Have two adjacent garden cabins with pitched roofs, terminating at the eaves at nearly the same height, approx 300mm between the two. Want to create a box gutter to keep this passageway (4m long) dry. What's the best way of lining it - lead sounds like it's too heavy and slope may be insufficient to prevent 1500mm lengths overlapping from capilliaring water, unless i solder, which seems to defeat allowance for movement/expansion from overlap.

All ideas greatly appreciated.
Thanks

 

[chappers]

lead is your best bet , but should be dressed up under both roof coverings and it shouldnt be too difficult to build a structure sufficient to take it.
Use firring pieces covered by ply to create a fall to the gutter outlet.

 

[swidders]

Thanks for that. Given there will be a small slope (1 in 80??) along its run, do i do an overlap weld or not? Sorry if this sounds daft.

 

[chappers]

Ideally i would try and get a 1in 40 fall but just overlap the lead you can just turn back a small lip on the underneath bit of lead to be on the safe side and maybe join with a bit of roofing mastic if you are overly worried, keep your lead lengths down to about 1500mm in length.

 

[swidders]

Thanks. Code 4 lead?

 

[justlead1]

Hi. If you can discharge gutter at both ends (high point in middle) run away from middle with 1:80 fall, use code 5 sheet lead, put a 50 mm by 100mm across gutter at middle. Dress the code 5 so it has a min 50mm upstand on both sides of the 50 mm x 100 mm and cap same with sheet lead. As for weight this will not be a problem as the structure needs to be able to carry the mass of pedestrian traffic when installing and cleaning gutter. good Luck