Copper plate on base of old porch posts and columns

[blueman]

In taking apart my old post, I noticed that the column and posts all had a sheet of copper nailed to the bottom side.

Was this used to prevent rot with the idea being that the natural corrosion of the copper would cause copper ions to leach into the wood thereby protecting it with the natural microbacidal effect of copper?

Just curious to understand how they did it in the old days...

Also, since these old column are still in excellent shape, would it make sense to replace the now corroded sheet with a new one to give it future protection?

Thanks...

[EXT]

It probably helped both with the copper ions, as well as protecting the end grain from being in contact with the wet floor be it wood or concrete, reducing the tendency to wick water up into the post hastening deterioration. I would go with what has worked in the past and replace the copper sheet with new copper.

[Bruce T]

I've never heard of this particular usage, but they used to put copper sheeting on the hulls of wooden ships to eliminate (or vastly reduce) the growth of marine organisms (bottom fouling). Actually, I think they still use copper-containing paint on ships hulls to this day (or at least until recently, perhaps....environmental issues??).

BruceT

[Fred the Red Shirt]

Copper flashing is less toxic and stronger than lead flashing, longer lasting than galvanized steel or aluminum and a century ago was much cheaper than aluminum.

The original dome of the Yerkes Observatory was covered with copper and it lasted about a hundred years.

It probably was there to prevent water from wicking up into the posts and columns. It also could have been there for termite and carpenter ant protection.

Hell yes! It worked fine all these years, right?

[Andy Dingley]

Yes, still done today too. Copper is affordable and very long lasting. Unlike lead, it doesn't corrode preferentially through pinholes.

Best to fold it over and nail through the sides though. You don't want to penetrate it.

[Ian Malcolm]

Cut the corners away so it doesn't trap water or stick it on with Sikaflex. If I was going to caulk ROUND but not right under the post, I'd drill a 1/4" drain hole through the deck under it for good measure.

[Lew Hodgett]

Have you checked the price of copper lately?

Around here, utilities install coppper wire during the day. thieves steal it that night.

Lew .

[Lew Hodgett]

Nice boat.

Lew

[Tim Shoppa]

For longevity measured in centuries in this application, copper is still the metal of choice.

They make galvanized post bases as well (check your lumber store, they come prefabricated for 4x4's etc.), but these are usually gone in a decade or so. A much thinner sheet of copper can last for a hundred years.

Good economics doesn't look at just the price per pound, but also at how many pounds you need and how long it'll last....

Several years ago, when copper wasn't nearly so expensive, the Baltimore subway system had a substantial amount of copper third-rail- electfication-cable, big honking cables to carry thousands of amps at

800V, stolen from an operating line!!!!!! Everyone is astounded at the audacity even today!

Tim.

[Ian Malcolm]

Thanks, I used to have a link to a photo in my sig, but that took the sig over 5 lines. [quick google] Yes its still up on Lee Yeaton's bayguide site:

:-)