Leaking zinc gutter pierced by corrosion: why? Emergency repair and what lasting solution?

[Christophe]

I had noticed leakage problems on some of my downhill gutters for a few years now ... in particular more or less significant oozing ... but I had left "pissed" (that's the case to say!) . With the violent storms of the last few days I decided to take a closer look ...

Well I was quite surprised to find that some gutters are pierced with multiple corrosion holes and become so thin that you can go through them and tear the gutter with your fingers !!

I think they are lead and / or tin welded zinc gutters ... they are a little less than 40 years old and the roof is slate with stainless steel hooks. I do not see well the electro chemical incompatibility that it could have? I have very little dirt in this gutter which has never been clogged!

So question: where does this corrosion come from? I don't understand ... Acid rain, poor material quality?

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For the emergency repair part, I cut out the most corroded parts and I plated some old plastic flowerpot as I could (a few necklaces, a little silicone glue). And I covered them with a roof waterproofing adhesive such as scotch Butyl ... it seems to be working pretty well ... for the moment!

For the least impacted holes, I simply put a bead of silicone glue ... it will hold what it will hold ...

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I would especially like to understand where it comes from and see if we can possibly avoid it with a simple tip upstream?

[GuyGadeboisTheBack]

The first thing would be to know what the material of your gutter is.

If it is galvanized steel, it could be injuries to the protective layer of zinc, either during placement or during subsequent interventions, but the zinc degrades to protect the steel, if you say that there are holes, they do not form in a few months, depending on the thickness.

On the other hand if it is zinc, the metal protects itself by creating a layer of oxides (the patina) which is light gray in color and not rust as you point out, the rust comes from an attack of iron or d 'steel.

If your bin is placed on a floor, the contact between the zinc and the points used in its construction (insufficiently pushed in or not protected) creates a galvanic couple which corrodes the zinc.

The rate of degradation depends on the humidity and the aggressiveness of your environment (plants or decaying leaves or others ...)

Good luck

https://gouttiere.ooreka.fr/qr/voir/273 ... s-cheneaux

[Macro]

I have some who are over 100 years old at home… .No this kind of problem… But there may be a way to dig? Roof defoaming products ???

Guy unsheathed faster than my ...

[GuyGadeboisTheBack]

I have some who are over 100 years old at home… .No this kind of problem… But there may be a way to dig? Roof defoaming products ???

Yes, but at home they must be zinc or "hot" galvanized like the 2Cv hoods of the 50s. Nowadays they are just galvanized.

[Ahmed]

Although you exclude this factor, an accumulation of leaves (without your knowledge) in an elbow could, during its decomposition generate enough acidity to explain this phenomenon on this zinc.

[GuyGadeboisTheBack]

Although you exclude this factor, an accumulation of leaves (without your knowledge) in an elbow could, during its decomposition generate enough acidity to explain this phenomenon on this zinc.

Pure zinc (or hot zinc plating) does not suffer from this defect, it produces an oxidized layer which protects it from attack.

[Ahmed]

Yes, this is true with regard to "normal" corrosion, since the oxide layer prevents deep propagation, but it is not sufficient to counter a massive attack such as the one I have described, or again the proximity of an oil stove pipe (sulfuric acid contained in the fumes) ...

[GuyGadeboisTheBack]

This is the very difference that there is between pure zinc which fears little and a symbolic galvanization as is practiced nowadays and which mainly concerns inexpensive imported products.

[Macro]

The gutter to Christophe at 40 years old .... It is possible that it is of low cost materials but ... I doubt it ... With regard to the welds .... In general the elbows and galvanized pipe are not not welded but held by folds ... Personally I really believe in a chemical attack either by the zinc worker with his zin7 or by the roaming demousseur with his chlorine cans ....
To be sure .... Christophe must do a magnet test ...

[GuyGadeboisTheBack]

Yes, maybe 40 years ago we made less crap. Or they are among the first to arrive on the market!