Metal Roofing in Salt Spray Applications
![](https://secure.gravatar.com/avatar/c3ce3e6b1c9b20f2509f22f805f4c540?s=52&d=https%3A%2F%2Fimages.finehomebuilding.com%2Fapp%2Favatars%2F200x200%2Fc.png&r=g)
I’m currently contemplating metal roofing material choices for an existing over (salt) water house here in the northwest. I’ve contacted a few panel manufacturers, suppliers and installers but have not been able to find information regarding the durability of Acrylic Coated Galvalume material for my application. I have installed this material, in 24 gauge, in a non-saltwater application and like it very much.
I have heard that Incralac is a good coating to apply after installation, but, cannot seem to purchase Galvalume with a “clear” coating which would provide protection similar to Kynar coating or similar coating systems.
The acrylic coating, according to one technical contact at a panel manufacture, should not be expected to last long.
Has anyone out there installed Galvalumne in saltwater applications and had a chance to assess the long term durability?
Any ideas regarding durability after Incralac coating? The new water based formula?Recommended?
Any experience or data on long term performance or any metal roof system in saltwater applications?
Thank you for any input, insight, information, or links.
Chris.
Replies
chris.. i live on an island in Narragansett Bay... i've always been trying to find a mfr who would warrant their product for installation here.. but so far i've found none..
don't get me wrong.. there are lots of metal roofs here.. but i don't think they have a warranty..
the problem is field cuts.. the factory finish stands up well.. but there are always field cuts and scratches.
i'd be curious to find what others have actually experienced .. with say, a 10 year track record in salt-spray / salt water enviornment
Mike, I meant to ask you when I saw you: Do they use much copper in your neck of the woods? I've noticed you use aluminum for flashing. How would a copper roof hold up there?Birth, school, work, death.....................
copper is traditional.. and lead-coat copper is preferred...
Barry was my copper guy.. copper here is usually reserved for big bucks,, or small areas..
the salt spray in the air in big storms means that the lead-coat copper is much preferred..
the painted aluminum coil stock that we use stnds up very well, about on a par with the copper...
we've only used the painted stuff since the mid-'80's. before that , the mill finish roll aluminum was the standard for everyone.. and that stuff never did hold up very well..
we also used a lot of roll lead flashing.... but i've noticed that that doesn't do well either, especially on the south exposures.... too much expansion/contraction leading to early failure from metal fatigue
and insights ?Mike Smith Rhode Island : Design / Build / Repair / Restore
We often get sideways blowing saltwater here (the Tacoma Narrows) and so far many painted metal roofs have held up well so far. In fact I know of no gross coating failures. Field cuts and scratches should corrode as they expose the carbon steel substrate as you said.
I'm not worried at all about warranty...just performance (as in climbing gear, who cares if it has a warranty if it breaks in the field!).
I just had a 4x8 foot standing seam copper roof put on a little wood shed to see how it weathers. Already it is bronze with a few blue spots. I'm hoping to put it on all of the pop outs on the house. Should be interesting. Lead coated copper huh? Fish and Wild Life probably would harpoon me if i put that up. What lifetime are you seeing with regular 16oz copper?
But I think I should be able to get decent performance out of Galvalume if i can get it factory coated, at least as good painted metal...just can't find a supplier. Or an experience base for the Incralac (brushed on) coating or untreated galvalume.
I did figure out how to search the archives here, but, nothing on saltwater exposure or comparison of galvalume and kynar coated materials...
Mike, why not light gage stainless steel flashing? It's not too expensive, even custom made. It's easy to handle, form, and cut....
how about aluminum roofing?
Mike,
Any thoughts on using saltwater to preserve your untreated wood deck material? Some have suggested that saltwater rinse every month or so will actually preserve the wood.
Chris.
Severe Environments:For corrosive environments, AEP SPan offers DuraTech¯hb high build primer, and DuraTech¯ tf thick film coating using G-90 substrate which provide for superior performance in severe marine, industrial and chemical environments. Please contact your AEP Span representative for details.
Check it out. I think it comes with a 20 year warranty.
thanks... couldn't find the spec for treating field cuts .. did you see anything about it
also... they're in Dallas, TX.. kinda far to ship to New England.. area distributors ?Mike Smith Rhode Island : Design / Build / Repair / Restore
I think you just pay more freight, but, for a warranty and product made for salt spray, it might be worth it, not sure. i understand you need to order somewhere around 3000 square feet before it is cost effective regardless of your location.
Field cuts may be better dealt with by hooking and hemming. my limited experience with the stuff is that you order the pieces to length which are run off coil. you then hem and hook so that none of the (factory) edges are exposed directly to the elements. check out the AEP SPan installation instructions.
http://www.aepspan.com/cadd/ARCH/DESIGN_SPAN/DesignSpan_DI.PDF
i haven't given up on coated aluminum and stainless steel. i'm within weeks of needing to get the stuff ordered for my next project.
This is kindof irrelevant, but I will post it anyway.
There is one island in the Inland Sea of Japan that gets a fierce blown salt spray, so fierce that it devours automobiles. Cars on the island last an average of about a year and a half before the bodies rot out. As a result, nobody buys new cars, just old used cars with only a couple year life left in them.
I saw this spray in action one time when crossing the big bridge at Akashi in a light drizzle. When I got to the other side the car was coated with white, as though it had been sprayed with milk. Salt spray.
Scary stuff.
Perfectly relevant!
aluminum pits fast in the environment here. I have an older furling deck shade that, has such bad pitting and general corrosion that it can no longer be unfurled. i'm certain there are marine grade aluminum materials out there, but, they are not readily available in roofing sheet stock locally. Asthetics do count even though this is the Northwest. Galvalume is not too shiny. Perhaps that is a good pointer though, and i should push my local sheet metal company to try harder to get a marine grade aluminum (but i'm learning not to ask for non standard materials as i'm not gold).
You guys plus some archival posts are making me think that the Galvalume is should be considered a "weathering" material subject to long term maintenance.
i'm installing a few small glass roll up garage doors, and will probably get alunimum anyhow. Powder coating is anotherr 50% in cost and i don't mind the pitted look, so, will probably go with it since they will not lose functionality in the near future as they pit....and there is the question of waterbase Incralac..,
Thanks for the chatter.