Spray Foam and Rust Issues

Ok, I really don't want to create a mess or open a can of worms here, but I really have some questions on the potential for rust in a steel shed/building when insulating it with CLOSED cell spray foam.

I know a LOT of folks have foamed probably thousand of sheds/buildings. I don't know how many of them have seen any rust issues.

I don't know how long it takes to show up, if it does. 5 to 10 years? 10 to 15 years? Longer?

Are there more problems with open cell foam vs. closed cell foam?

How much is climate/environment a factor. In the south you have constant moisture/humidity. But in the north you have freezing weather and ice, much more contraction/expansion due to temperature extremes. Is this a factor?

Is it due to a chemical reaction? If it is, are the formulations the exact same now as they were?

SHOULD a rust issue develop is it evident from the outside and therefore can be addressed promptly before a major issue develops? It seems using closed cell spray foam (that doesn't readily absorb moisture) would preclude the issue from developing from the inside out?

Of all the folks on here that have had their shed/buildings spray foamed for a decent number of years how many have actually had any issues with rust that could be blamed on the application of the foam itself and not some other factors.

Like I said, I'm not trying to start any flame wars or arguments, but is it possible we can explore the issue a little more?

Thanks,
BobL.

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I had a building spray foamed w closed cell for about 7 years and there was absolutely no rust issues. In fact the mold and mildew growth on the outside of the metal was dramatically reduced. I really had not even heard of a rust issue except it was mentioned somewhere on this forum.

I have been called on two buildings so far with rust issues. One each open and closed cell. Both about eight years ago. Both buildings need to be stripped of all insulation and sheeting. One building needs some girts replaced.
None of the spray foam guys around here will spray directly on sheet metal any more. We note in our contracts that spray foam applied to the metal will void any future warranty.
This is a developing problem and one that is going to be very expensive.

readhead said:

I have been called on two buildings so far with rust issues. One each open and closed cell. Both about eight years ago. Both buildings need to be stripped of all insulation and sheeting. One building needs some girts replaced.
None of the spray foam guys around here will spray directly on sheet metal any more. We note in our contracts that spray foam applied to the metal will void any future warranty.
This is a developing problem and one that is going to be very expensive.

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readhead, thank you for your input. I am not trying to be argumentative here, just a sincere attempt to seek relevant and accurate info to help me make an informed decision. That being said...

Two buildings does not really seem statistically significant considering all the spray foam jobs that have been done. And this was 8 years ago. Have you not seen/heard of any issues since then?

On these two buildings that you have had some level of personal experience with, can you give any details? Like, do you know if the foam was applied to these particular buildings when the buildings were recently constructed or was the foam applied to older structures maybe?

Was there any extenuating circumstances noted or considered?

How long had the foam been applied before the issues occurred?

Is it possible the issues with these buildings was somehow related to the quality of the installation of the spray foam by the insulators?

I sent an inquiry to Carolina Carports asking for recommendations on the best way to insulate my shed. I received a call back and the guy on the phone said spray foam was the best way to go. I asked him if it would void the warranty and he said yes.

Now on the warranty issue. It seems to me that the application of spray foam is really a modification to the structure considering it is sprayed directly on the metal. And with the real issues concerning replacing any metal, should it become necessary for any reason, I would void the warranty too if I were them, potential for rust issues aside.

Again, not looking for an argument, but any additional info you can offer would be very helpful.

Thanks,
BobL.

This was within the last year. The foam was installed eight years ago. They seemed like typical spray foam installations. I suspect that since the buildings were erected without any thermal break between the sheeting and the purlins and girts and these components were not sprayed that condensation may have formed and worked its way to the sheeting. That is only an observation and I can't really say for sure.
Spray foam is a great product and performs very well but this particular application is starting to see problems. A lot of building providers, both pole buildings and metal buildings, are unaware of the problems or don't care. Blanket insulation is still the easiest and least expensive way to go.

A sponge is an example of open cell foam. Open cell foam holds moisture.

Closed cell can be saturated, but that requires that is be exposed to water (not just humidity) for a long period of time. Much less chance of rust.

Of course, all of the metal and all of the fastener should have proper rust proofing (baked enamel paint or powder coat; not dipped galvanized fasteners).

Thanks for the additional info readhead.

BobL.

Closed cell foam is used in industry -- it's applied to metal all the time with no problems.

Foam is not a perfect product -- if not mixed and applied property, voids can occur. A thin layer applied first allows visual inspection and minimizes heat. My guess --- voids .. that's what is happening.

There is only so much you can leave out of a building. I think people take the cost savings too far with pole barns ... if you are not going to have some sheathing layer IMO its best to stick with something that you know will work -- that's why they have the fully enclosed large batts w/ heavy vinyl interiors for pole barns -- they are utility buildings. It also allows for replacement of damaged siding.

IMO those wanting both a pole barn and a foamed conditioned space should have sheathing of some kind.

Closed cell foam is an effective vapor barrier. Open cell foams breathes much better and in your climate could lead to the formation of condensation on the steel. Even closed cell foam could allow condensation to form if it was applied too thin.

If you're worried about rust, you could always spray some type of coating on the steel as a precaution before applying the spray foam.

There are articles on BuildingScience.com or you could visit the Q&A forum at GreenBuildingAdvisor.com to find out how thick the closed cell foam needs to be to avoid condensation issues in your climate and whether or not open cell foam would be okay to use.

In my climate open cell foam would work fine and would be a substantial savings compared to closed cell foam.

DC

This foam subject has been cussed/discussed many times. We will, all of us, believe what we want to believe whether it is based on facts or not. I am of the opinion that rust issues are likely to be more of an issue for/on/in/with buildings that are less-than-perfectly assembled. Of course, I could be wrong as I only have 40 years experience in the construction business and have not been involved in every state in every climatic zone. Use what works in your local environment and ignore info that comes from and works well in tim-buc-too or bum-fuk-Egypt.

Some good reading here: http://www.energsmart.com/spray-foam-insulation/open-vs-closed-cell-foam.html

semi75 said:

I had a building spray foamed w closed cell for about 7 years and there was absolutely no rust issues. In fact the mold and mildew growth on the outside of the metal was dramatically reduced. I really had not even heard of a rust issue except it was mentioned somewhere on this forum.

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Where is the building located?

These threads are worthless unless the members include the location of the buildings they have experience with.

73RR said:

...I am of the opinion that rust issues are likely to be more of an issue for/on/in/with buildings that are less-than-perfectly assembled....

Some good reading here: http://www.energsmart.com/spray-foam-insulation/open-vs-closed-cell-foam.html

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I think this is the key - either you keep all water from getting in or you provide a way to get it out.

Without perfect materials and technique, you're likely to get moisture inside, whether through a leak (construction issue) or by condensation (insulation issue) and then the foam doesn't let it drain or evaporate. You get mold/rot/rust.

Of course you don't know if you have a rust issue because it hasn't come through yet. Or you may not have one at all.
This type of building by it's nature is usually a low cost option and won't see the type of detail that a home would see.

The more you read, the more you will find the best way is to spray foam a pole building is to use OSB or a similar type of sheathing on the outside frame of the building and tape all the joints, then install the steel sheathing. Then when you spray the foam... it's not against the steel.

That's why those big batts of insulation that are made for pole buildings are basically a big poly bag full of insulation. It keeps the insulation off the steel, which allows the insulation to stay dry and provides air space for any moisture infiltration between the steel and the poly to dry.

DC73 said:

..visit the Q&A forum at GreenBuildingAdvisor.com to find out how thick the closed cell foam needs to be to avoid condensation issues in your climate and whether or not open cell foam would be okay to use.

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OP, I would also suggest you visit GreenBuildingAdvisor.com. There is a lot to the science of spray foam. Location and application has everything to do with its success or failure.

Here's an example of the kind of fact based answer you'll get from the GreenBuildingAdvisor.com folks:

"Metal siding is highly vapor retardent, but not air tight, so as long as there is at least SOME cavity between the metal and the rest of the assembly, the assembly will be able to dry toward the exterior.

The coefficient of expansion of metal siding and polyurethane differs by quite a bit, and yes, spraying closed cell directly onto the siding WOULD create warpage that shifts with season & sun.

Packing fiberglass batts directly against the metal is guaranteed to end up with wet spots in the insulation- bad idea, which can only made worse by putting poly on the interior. If you're going to put insulation directly against the metal, use rigid EPS, and don't glue it to the metal- support it by other means. Open cell foam might get you there too, and has more flex than closed cell, but would be somewhat susceptible to moisture from rain at the seams"

Read more: http://www.greenbuildingadvisor.com...trofit-metal-skin-pole-building#ixzz4k6Cp9oR3

To reply to a previous comment regarding location, my install was in KY. A nice humid location with heavy spring rains, storms and quite a few hail storms. I am in VA now and looking back KY was the land of metal pole barns and metal manufacturer's. A few have went out of business in the last 10 to 15 years. I had two pole buildings on the property, one was a 60x140 horse barn that had double bubble on the roof with no other insulation. The other was a 30x40 I built myself. It stayed un-insulated for close to 10 years before spray foam was added in 2010-ish. The metal from the buildings came -from two different manufacturers. One was ABC, the other was Dav-Co. I won't say which was which...

In my experience the large horse barn without spray foam had siding rust issues near the bottom of the sheets and drip edge trim. There was also a little on the roof sheets at the end near the gutter. Was the rust because I let the weeds get a little higher on occasion around the bottom of the sheets? Who knows but there were a few other rust spots that developed in the 17 years since I had it built. The 30x40 had absolutely no visible rust issues before or after the closed cell was applied. In addition to the insulation and structural soundness it added it also virtually eliminated the need to pressure wash the building of mold yearly. The mold growth was due to condensation, humid conditions and the distilleries in the area didn't help. I've also seen the same rust issues develop overtime in other metal building friends and relatives have built where either traditional vinyl backed fiberglass or no insulation at all was used while others looked pretty good 25 years later.

I'm just throwing this out there but frankly I think metal warranty for paint fade, chip and rust is **** at best. The metal manufacturer's remind me of Hardie Board paint warranties, there will always be someone to blame and labor isn't factored in. Of course that isn't true for the big pole barn companies that stand behind their product but I'm referring to a manufacturer warranty only. I can see exactly what redhead is referencing when there is so much extra labor and cost involved in replacing the metal with foam applied there is no room to say for certain hat caused the issue.

This long post is meant only to say... can you really lay the blame on the foam? It's easy for the pole barn builders to say don't use it because it makes our life hell if it needs to be replaced, but its another to prove foam is responsible. Given the qualities I have experienced I just built another pole barn after moving to VA and just had it sprayed last week. After being around metal buildings all of my life I consider them a subpar structure but add closed cell foam and man are they efficient and sound. Traditional insulation in a metal building just doesn't compare, if there is a rust issue down the road I missed I will be kicking myself for using metal not the foam. If I wanted to add the cost of USB before the foam that would also take away a large part of going with a pole barn to begin with.