metalwaterproofing
Is it possible to fuse sheets of the galvanized sheet metal that they sell at the hardware store for roofing together so that it is water tight?
I was thinking that this may be able to be accomplished with the same flux and solder used to fuse copper pipes, but I'm not sure.
The reason I am doing this is that I'm hoping to make some water tight trays that potted plants can be placed in.
Based on questions answered in chat you have a case where the contractor didn't measure the deck properly, and built it too high, could not flash properly under the door frame, and performed a "some genius" move putting a transition strip (meant for interior use) over top of the door frame and the vinyl, with caulk under neath.
Stupid.
Two options: 1 cheap and temporary, 1 expensive and proper.
Cheap: Use proper caulk (props to @tester101)
Option 2 - and the door is old so this isn't actually a terrible idea.
Replace the door. In the process, raise the rough opening of the door frame half an inch or so - however much is necessary to be able to put a proper piece of flashing under the door frame and over the vinyl.
You will probably have to custom order a door to fit your new rough opening, but at least you can seal the door area properly.
And props to @bmitch for pointing out that flashing needs to run the entire width of the deck.
The vendor will be able to give you this information based on the thickness they apply the material and any specs you gave or requested when they quote the job.
Best Answer
You can make watertight trays from flat sheet metal without soldering or riviting.
Take a sheet of metal whose
Fold the sheet so it ends up looking like this:
You can fold up one side at a time using a piece of wood (maybe 1x2), a bit shorter than the length of the side you are working on, as a bending edge.
Work around the piece, clockwise or counterclockwise.
You will have to work the angle fold in the corners as you move to each successive side. The angle corners will point outward initially. Then you bend them inward toward the short end.
All edges will end up at the height of the sides with no seams. The easiest kind of waterproof.