# Galvanized Drip Edge Rusting



## finethreads (Mar 21, 2020)

Hi all, my home is 5 years old. Live in Florida just a couple hundred feet away from the Gulf. Lots of humidity and salt in the air. After year two I started battling a rusting drip edge at the corners of my house where the vertical trim boards sit on top of galvanized drip edge. I have tried several times to address this issue.

Last attempt:
Sand paint and rust off down to metal
Coat with Ospho and let it dry
Prime with Sherwin Williams Pro Cryl primer
Top coat with Benjamin Moore Aura Satin

Within a week I have rust bleeding through again.

Any ideas on how I can address this issue?


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## Holland (Feb 18, 2011)

finethreads said:


> Hi all, my home is 5 years old. Live in Florida just a couple hundred feet away from the Gulf. Lots of humidity and salt in the air. After year two I started battling a rusting drip edge at the corners of my house where the vertical trim boards sit on top of galvanized drip edge. I have tried several times to address this issue.
> 
> Last attempt:
> Sand paint and rust off down to metal
> ...


Prime rust spots with oil based primer and re-paint. 

A water-based primer will only promote rust return.


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## finishesbykevyn (Apr 14, 2010)

I never understood why they don't leave a little space between drip edge and trim. Water and junk just gets trapped in there...


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## finethreads (Mar 21, 2020)

Thanks! I will try the oil based primer.


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## Joe67 (Aug 12, 2016)

You do have to get all of the rust out first, but trying to get *anything* to hold up around salt water is ... well a problem. Salt just eats stuff including the zinc coating that goes over steel to make it galvanized. Once you work it again, perhaps just add inspecting and recoating that to your spring & fall maintenance lists (if you do such things).


You very well may be asked to move this question to the associated DIY forum (where many of the pros here also answer).


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## Lightningboy65 (Mar 12, 2018)

I'm not going to sugar coat....that's going to be an ongoing problem, no matter what you do. The problem is in poor design. While the extended water table trim board looks good, the top is a water trap. Aluminum, copper , or lead (depending on time period of construction) edge should have been used. Anything but steel. The building doesn't look that old (less than 50 y maybe?)...they should have used aluminum.


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## finishesbykevyn (Apr 14, 2010)

Lightningboy65 said:


> I'm not going to sugar coat....that's going to be an ongoing problem, no matter what you do. The problem is in poor design. While the extended water table trim board looks good, the top is a water trap. Aluminum, copper , or lead (depending on time period of construction) edge should have been used. Anything but steel. The building doesn't look that old (less than 50 y maybe?)...they should have used aluminum.


 Building looks brand new to me. Still a bad design. Atleast they put a metal flashing on top of the wood. Around here, people use those stupid wooden drip edges with no metal flashing over them. Water sits on it and rotts the whole bottem if the house out. Stop it. Just stop it. Another classic spot is the horizontal trim boards following the roof line and windows with no drip edge. They all rott out. So sad.


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## Holland (Feb 18, 2011)

finishesbykevyn said:


> I never understood why they don't leave a little space between drip edge and trim. Water and junk just gets trapped in there...


Agree. There should be a space between flashing and trim to allow it to dry out. Looks tight.


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## Redux (Oct 27, 2018)

I’m thinking that a conventional oil primer would saponify and quickly fail if in contact with galvanized steel. If the existing paint and rust were removed from the flashing, I’d opt for something such as Corotech ORGANIC ZINC RICH PRIMER V170 and top coat it with an thermoplastic compatible acrylic. The zinc in the primer will provide cathodic protection against rust. The Corotech product is MPI approved for that type of application whereas conventional oil primers aren’t. It is however a bit pricey just for a few flashings.

You could try looking into some of the zinc rich primers or rusty galvanized steel primers on MPI’s approved product list. 

http://www.specifypaint.com/APL/paintinfo_APL_new/ProductIdxByMPInum.asp


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## Holland (Feb 18, 2011)

Redux said:


> I’m thinking that a conventional oil primer would saponify and quickly fail if in contact with galvanized steel. If the existing paint and rust were removed from the flashing, I’d opt for something such as Corotech ORGANIC ZINC RICH PRIMER V170 and top coat it with an thermoplastic compatible acrylic. The zinc in the primer will provide cathodic protection against rust. The Corotech product is MPI approved for that type of application whereas conventional oil primers aren’t. It is however a bit pricey just for a few flashings.
> 
> You could try looking into some of the zinc rich primers or rusty galvanized steel primers on MPI’s approved product list.
> 
> http://www.specifypaint.com/APL/paintinfo_APL_new/ProductIdxByMPInum.asp


If it's rusting, the zink clearly is no longer on the steel. And besides, its already painted. Going over the existing surface should not be a problem.


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## Redux (Oct 27, 2018)

Holland said:


> If it's rusting, the zink clearly is no longer on the steel. And besides, its already painted. Going over the existing surface should not be a problem.


If prepping and exposing steel, coating over zinc with oil can be a problem.

First photo is of a galvanized steel overhead door prepared, spot primed with oil rust inhibitive primer, and refinished. The oil primer saponified within 4 months resulting in rust returning.

2nd photo is of the same galvanized steel door re-prepped, spot priming only bare metal with zinc primer, and refinished 2 years ago. No saponification or rust.

It works..the oil primer didn’t work due to residual zinc..


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## Holland (Feb 18, 2011)

Redux said:


> If prepping and exposing steel, coating over zinc with oil can be a problem.
> 
> First photo is of a galvanized steel overhead door prepared, spot primed with oil rust inhibitive primer, and refinished. The oil primer saponified within 4 months resulting in rust returning.
> 
> ...


Needlessly complicated using an obscure product. 

Prime the rust spots with an oil based primer and re-paint.


*underlying problem (flashing tightly touching trim) will cause routine maintenance no matter what.


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## CApainter (Jun 29, 2007)

I was able to fend off a similar problem in a similar environment after rust converter, oil primer, and oil finish failed . What worked for me was removing as much of the rust scale as possible by grinding, followed by a couple of coats of a high build epoxy (Devoe Bar Rust for example), followed by a couple of coats of an acrylic architectual finish product. 

The key to preventing rust, or existing rust from re-occurring, is to create as thick of a film barrier as possible. Typically, this can only be achieved by amide epoxies. It's a lot of detail to remedy a poor metal material choice to begin with.


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## Brushman4 (Oct 18, 2014)

Lightningboy65 said:


> I'm not going to sugar coat....that's going to be an ongoing problem, no matter what you do. The problem is in poor design. While the extended water table trim board looks good, the top is a water trap. Aluminum, copper , or lead (depending on time period of construction) edge should have been used. Anything but steel. The building doesn't look that old (less than 50 y maybe?)...they should have used aluminum.


Years ago the wife and I went down to the Florida Keys for a 3-week vacation. One night we were out late walking back to our nearby Hotel from a bar on the Overseas Highway. We kept hearing this crackling, sizzling type sound and couldn't figure out what the hell it was. The next morning we went out for breakfast and asked some of the locals where the sound was coming from, they all laughed and said it was the salt in the air burning off of the high tension wires above the roadway.


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## SemiproJohn (Jul 29, 2013)

Brushman4 said:


> Years ago the wife and I went down to the Florida Keys for a 3-week vacation. One night we were out late walking back to our nearby Hotel from a bar on the Overseas Highway. We kept hearing this crackling, sizzling type sound and couldn't figure out what the hell it was. The next morning we went out for breakfast and asked some of the locals where the sound was coming from, they all laughed and said it was the salt in the air burning off of the high tension wires above the roadway.







With a purposeful grimace and a terrible sound
He pulls the spitting high tension wires down


Saltzilla!


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## finishesbykevyn (Apr 14, 2010)

I agree, the only way to truly get the problem under control is to grind all the rust off and prime with proper rust inhibitive primer. This may be hard to do though as the rust may be leaching from behind the trim or from the under side. As it's not in a detremental spot, hence hindering the integrety of the structure, I probably wouldn't put too much effort into it. (like Holland said)I would however trim a 1\2" off those corner trims though for some breathing room..


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## RH (Sep 7, 2010)

Thanks for posting on PaintTalk.com. The Moderators of this forum would prefer that you post Do It Yourself related topics on our sister site.www.DIYChatroom.com 

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