Making a strong seam in galvanized sheet?

Naio wrote:
Bobs, your directions are beautifully clear, and I have a hand bender and a sledge! Thank you so much!

You're welcome! :)
Glad to share some if my forty something years of making stuff with metal!
You were fast, you answered while I was editing my post a couple times!

Bobs, your directions are beautifully clear, and I have a hand bender and a sledge! Thank you so much!

I've been in the metal bashing business since I was a puppy. Sunrooms, patio covers, screen rooms and so much more. As such, I have had to get creative and custom fab many things over the years, including stuff similar to what you describe.

Enough about me, now onto you! :B

Do you have access to a brake? (A sheet metal bender) if not, no problem.
You can pick up a small hand held pair of metal benders for fairly inexpensive.

Take the two pieces you want to join together and make a 1/2" or 3/4" hem bend in it.

A hem is a 180 degree overbend in the metal, similar to a hem in a dress or pair of pants.

Bend it about 175 degrees and leave a slight gap in the overbend.
Now cut a piece of the same material in a length equal to 4 times the size of your hem bend. If you do a half inch hem, the you cut your piece about 2 inches.

Make the same hem bend in this piece from both ends so your little overbends, (hems) are close to, but don't touch in the middle. Leave about 1/8" between the two ends you bend over. The end of these two bends will be facing each other. But leave them also at about 175 degrees.
This piece is your joiner strip.

Now take the 2 pieces you want to join together and butt them to each other. Take the little joiner strip you made and you slide it over the pieces to join. You now have both raw ends of the metal inside the hems of the opposing pieces.

Once in place, get a large metal object such as a small sledge hammer or small anvil or any facsimile of one and hold it against the outside that will be seen. Take a regular hammer and hit it from the opposite side, flattening your 4 hems together so they are tight 180 degree bends beat together for a permanent joint.

From the outside, you will now see 2 neat ends of 2 pieces of metal touching each other with no visible fasteners. And it will be every bit as strong as the original piece. And if you want waterproof, apply some butyl or similar caulking inside the joined surfaces prior to assembly.

Really simple and easy to do.
If I could somehow post a diagram here I would.

Does this make sense? It takes very little time to do.

Stainless anything a waste of money. Galvanic protection. #10 sheet metal machine screws. Drill 3/16" hole. Use flat washers both sides. One screw per inch in lightweight sheet.

Trackrig wrote:
the bolts would be fine, but if you don't want them seen, use 5 - 6 pop rivets.

X2. Keep it simple.

fj12ryder wrote:
I think Trackrig has the right idea: 1-2 inch lap seam secured with pop rivets or stainless bolts, using washers to spread the stress.

Definitely no welding galvanizing, very toxic.

Just curious, how do you do that for a round hole/fitting?

I think Trackrig has the right idea: 1-2 inch lap seam secured with pop rivets or stainless bolts, using washers to spread the stress.

Definitely no welding galvanizing, very toxic.

It doesn't need to be even slightly waterproof. It just needs to resist the weight of the soil

No you cannot weld zinc coatings, or should not anyway. The coating need to be removed first. As to your other question, it's hard to say without more details: a drawing and what gauge sheet metal.

Do you mean strong as in physically strong or as in a strong seal?

I'm going to be working on a small project myself where I'm more worried about sealing the two pieces. I think I'm going to have the sheet metal shop fold over the edge on each sheet by 1", then slide the two folds together with a good sealant. I haven't decided on the sealant yet.

Addition - the bolts would be fine, but if you don't want them seen, use 5 - 6 pop rivets.

Bill