Tag Archives: galvanized steel

Fire Separation When Living With Large Animals

Fire Separation When Living With Large Animals

While barndominiums and shop houses have become quite a rage, for years we have been providing fully engineered post frame buildings combining animals (most often horses) with living spaces (usually as a full or partial second floor). Along with this come some perhaps unexpected design considerations.

Reader LISA in SNOHOMISH writes:

“I am finishing a loft apartment above a 6-stall barn in a pole building.  Snohomish County has indicated they want the ceiling of the barn and all posts and beams supporting the loft apartment to be covered in 5/8″ Type X Gypsum for fire protection.  

Gypsum on the ceiling is not a problem but, Gypsum on the posts is as horses will chew anything they can get their teeth on.  Is the requirement for Gypsum on posts and beams in this type of application normal?  Is there another way to fire proof these elements besides wrapping them with Gypsum, cement board, etc. Snohomish County does not seem too familiar with pole building construction and I am hoping there is some other kind of fire proofing (paint on or?) that would satisfy them.

Thank you.”

Mike the Pole Barn Guru responds:

Considering we have probably provided a hundred or so post frame (pole) buildings in Snohomish County, they actually do have more than a passing familiarity with them.

Hansen Buildings Horse BarnBecause you are combining dissimilar uses (large animals and a residence) you are required by Building Code (as well as your safety) to fire separate them. This is just one of many considerations when it comes to living adjacent to or above animals (others include high insurance costs, dust, noise, odors, insects, rodents and in your case having to go up and down stairs). For all of these listed reasons I always encourage those giving this combination consideration to ponder it carefully before moving forward, as well as to budget accordingly.

Most jurisdictions require one-hour (two layers of 5/8″ Type X gypsum wallboard) while I have even seen two-hours in some instances. In two-hour scenarios, any interior stairs must be fire protected from lower areas entirely and exit/entrances must be to the exterior, not to barn areas. 

Given what you have, your best bet will be to wrap members as the county requires, then cover anything within chewing range with galvanized steel or bare aluminum trims. These trims can be bent by either a steel roll former or a sheet metal shop in order to best fit with their field application and installed with screws through to underlying wood members.

Yes this is alot of work! But the main reason is safety, for both you and your horses. What’s that old adage which says, “an ounce of prevention is worth a pound of cure.”

Minimum Steel Substrate Coating

Minimum Steel Substrate Coating for Residential Steel Roof Panels

When it comes to residential buildings – whether your barndominium or shouse (shop/house) is stick frame (stud walls), post frame, PEMB (pre-engineered metal building) or some other structural system with a steel roof, there is one import aspect of this roofing material frequently overlooked.


Most popular metal roofing steel substrates are Galvanized and Galvalume. Galvanized substrates are coated in zinc, while Galvalume substrates are coated with an alloy of zinc plus aluminum. Both Galvalume and Galvanized are good substrates for metal panels. 

With Galvanized substrates, greater zinc amounts mean greater protection against panel corrosion. Two commonly used Galvanized substrates are designated as G100 and G60. These designations relate to the total amount of zinc contained on both sides of panel surfaces. G100 contains 1.0 ounce of zinc for every one square foot of panel while G60 substrates contain 0.6 ounces of zinc. This means a G100 substrate contains 66% more protective zinc than a G60 substrate. This difference will have a direct correlation to panel longevity and long-term aesthetics of your barndominium.

For most applications, a Galvalume substrate offers best long-term solutions, and Galvalume’s superior performance has been field proven. Over four decades of testing has shown Galvalume delivers superior corrosion resistance compared to Galvanized panels. In fact, Galvalume’s construction industry performance  has been so superior, steel mills warranty it against rupture, perforation, or failure due to corrosion. Similar warranties do not exist for Galvanized.

In one test, unpainted Galvalume and Galvanized panels were placed in four different types of outdoor environments, including normal marine and a rural setting. After 23 years of side-by-side comparison in all areas, Galvalume was two to four times more durable than Galvanized.

For extended reading on Galvalume: https://www.hansenpolebuildings.com/2013/04/galvalume/

SO what does all of this have to do with your new barndominium?


Building Codes (IRC – International Residential Code and IBC – International Building Code) address substrate requirements for steel roofing.

IRC Table R905.10.3(2) requires a minimum of AZ 50 for 55% aluminum-zinc-alloy-coated steel (Galvalume) or G-90 for Galvanized steel. These same requirements can be found in IBC Table 1507.4.3(2).

What is absolutely amazing is – America’s largest roll former (at least in terms of quantity of machinery) has this on their website for their 29 gauge panels, “…..perfect for residential roofing….”, however when one digs deeper on this website, this panel has only G-60 galvanization, meaning it cannot be used for roofing on anything other than “U” buildings by Code. Only an upgrade to this manufacturer’s 28 gauge “Pro” product will meet residential Code requirements!

Be an educated buyer – know what you are investing in and be certain it is indeed Code conforming. Chances are your contractor, kit provider or maybe even your roll former is unaware.

Best Barndominium Steel Roofing and Siding in Coastal Areas

If you are one of many looking to install steel roofing and/or siding on your new barndominium, shouse (shop/house) or post frame home, understanding differences between galvanized and galvalume is essential to getting top performance you expect from your new steel roofing or siding..

In most residential steel roofing applications including near-coastal areas — beach homes located near shore, and even homes located in the middle of heavy salt-spray — severe marine environments, Galvalume steel will be a better and more corrosion-resistant option than galvanized steel.

Read more about Galvalume at https://www.hansenpolebuildings.com/2013/04/galvalume/

Galvalume steel should not be used in contact with concrete or mortar, as both are highly alkaline environments. Bare Galvalume steel and painted Galvalume sheets will suffer rapid corrosion when in contact with mortar and concrete.

Bare Galvanized steel and painted Galvanized steel perform better in this type of environment.

Now, because aluminum, one of two metals in Galvalume coating, provides a barrier protection for steel, instead of galvanic or self-healing protection in galvanized steel, scratches and cut edges in Galvalume are less protected.

Galvalume steel is best for use in prefabricated metal wall panels and standing seam metal roof applications with concealed fasteners.

Normally, Galvalume is offered in both bare and pre-coated (pre-painted) versions. Most residential-grade Galvalume metal roofing products – like galvanized steel – are coated with Kynar 500 or Hylar 5000 paint finishes. (For extended reading on Kynar: https://www.hansenpolebuildings.com/2014/05/kynar/ )

Galvalume has an excellent performance lifespan in bare exposures (unpainted panels) as well. Both galvanized steel and Galvalume weigh 100 to 150 pounds per 100 square feet and contain about 35% recycled steel post-consumer content.

Galvalume is similar in investment to galvanized steel.

In the early 1800s galvanized steel was invented and developed for commercial use, so it has nearly 200 years of proven track record. Carbon sheet steel is dipped in molten zinc. It’s more than a coating, however. A chemical bond occurs and produces telltale “spangles,” a crystalline surface pattern found on galvanized steel.

Bethlehem Steel developed galvalume introducing it to the world in 1972, so it’s been in use nearly 60 years. Similar to galvanized steel, Galvalume is produced by a hot-dip process. Instead of 100% zinc, this dip is 55% aluminum, 43.5% zinc and 1.5% silicon.

  • Zinc bonds with a steel surface to create a barrier to corrosion-causing moisture
  • Aluminum naturally resists corrosion and reflects heat too
  • Silicon enhances coating adhesion coating, keeping it in place when steel is rolled, stamped or bent

How Corrosion Occurs in Each

Unpainted Galvalume vs. galvanized steel exposure over time.

Death of metal roofing, as we all know, is corrosion. Galvalume and galvanized steel roofing are affected differently by corrosion.

Galvalume: Aluminum has tremendous corrosion resistance, so it will generally corrode more slowly than galvanized steel. One exception is when coating is penetrated – scratched or chipped by falling or blowing debris, for example.

This exposed sheet metal beneath the coating will quickly corrode. However, aluminum coating will prevent corrosion from spreading; it will be contained.

Galvanized steel: More than just coating steel, galvanizing steel produces a chemical bond resistant to corrosion, scratches and nicks. Galvanized steel will self-heal for small scratches and along cut-edges.

Over-time, when galvanization layer in galvanized steel panels wears down or is penetrated, corrosion will begin to spread.

Uncoated/Unpainted Galvanized Steel vs. Galvalume Wear: 10, 15, 20 Years and Beyond

To illustrate differences in performance between galvanized and Galvalume steel, let’s consider how these two kinds of steel would perform in an uncoated/unpainted steel roofing application.

Note: With a quality paint finish such as Kynar 500, both G-90 galvanized steel and Galvalume steel should provide consistent, rust-free performance for 30 plus years when used in accordance with manufacturers’ specifications.

With unpainted steel galvanized steel often holds its rust-free good looks longer than Galvalume thanks to self-healing properties of zinc.

5 to 10 Years: A galvanized roof will look “perfect” except for some corrosion beginning where fasteners penetrated steel during installation. Galvalume roofing may show corrosion at nicks and scratches and around field-installed fastener holes.

10 to 15 years: Galvalume roofing will look about the same, but with a few more nicks producing isolated spots and lines of corrosion. Galvanized steel roofing will start showing its age. Corrosion has continued to spread outward from its starting point.

20 years: Changes in Galvalume roofing are slow and imperceptible, though if you compared a picture of the roof when new to its current state, nicks and scratches would be visible. You might also notice a slight patina common to ageing aluminum.

Galvanized roof, depending on climatic factors, might show a light rust hue. This is a result of the zinc layer wearing away, leaving steel substrate exposed.

Beyond 20 years: Lifespan for unpainted galvanized roofing is 15-25 years depending on climate, less where oceanic salt spray is common. Unpainted Galvalume has a lifespan up to 40 years. Once corrosion has penetrated any steel roofing substrate, steel integrity will suffer and your steel roof will begin to fall apart.

For maintaining good looks and longevity in coastal applications Kynar paint over galvalume is a winning combination!

Spray Foam Insulation, Steel Roofing and Corrosion

Hansen Pole Buildings’ Designer Rachel recently had an interesting discussion with a client. The gist of the discussion was the client had heard spray foam insulation will corrode the steel and void the warranty of the steel.

Rachel did some research and found this article: https://www.greenhomeguide.com/askapro/question/can-i-apply-spray-foam-insulation-directly-to-the-underside-of-a-metal-roof.

When I added the external elevator shaft to the rear of our steel covered post frame home, my choice of insulation was closed cell spray foam. Although I knew it was going to be more expensive than other choices of insulation, I was (and remain) convinced of it being a superior R-value, as well as completely sealing the system. In the case of our addition, the steel roofing was applied directly over the wood roof purlins, without any solid sheathing or other barrier.

So, will spray foam insulation actually corrode the steel?

Highly unlikely, as from the research I have been doing there appear to be no chemicals in the spray foam which would react with the steel or the galvanized or galvalume protective layer over the bare material. Most steel roofing is factory finish painted, which adds yet another barrier surface in the interior primer paint coat which further isolates the steel from the spray foam.

There are some cases where I could see some challenges.

One would be if someone went on the cheap and used open cell spray foam, rather than closed cell. In this case moisture could get through the open cells and be in contact with the underside of the roof steel.

The other could occur if there was a leak in the roofing or the ridge cap which would allow moisture to get trapped between the roof steel and closed cell foam.

As to the warranty discussions – steel warranties primarily cover fade and chalking of the exterior finish of the steel. Personally I am hard pressed to see how it is the application of closed cell spray foam insulation on the interior of the steel roofing, would influence the life of coatings on the exterior.

Of course everyone looks for an “out” when it comes to warranties, and the reality is a good warranty protects the seller/manufacturer far more than it protects the consumer.

If I had it to do all over again, I would still closed cell spray foam my own steel roofed building. Check back with me in another thirty or forty years and see if my opinion is yet the same.

Buying a Used Pole Building

40’ x 60’ Used Pole Building – $14000 (Silverton)  SERIOUSLY?

The following ad appeared in the Salem, Oregon Craigslist December 6, 2016 in for sale > farm & garden – by owner:

“I have a nice fully enclosed 14 foot tall pole building. It is fully disassembled and ready for transport. All the metal is fully galvanized. The building has a clear span with 4 double trusses and framed ends.”

Now, the ten top reasons why buying this used pole building would be so wrong:

#10 It is all galvanized steel – generally most folks do not find this to be aesthetically pleasing!

#9 You are going to have to pick it up and transport it – plan on a semi pulling at least a 40 foot long trailer, because those trusses are 40 feet long! Might be handy to have either a boom truck or a forklift there to hoist everything onto the trailer;

#8 And unload it when it gets to your site – some offloading equipment could be handy here;

#7 It isn’t designed to current Building Codes – so you cannot get a permit to erect it – Oregon DOES have an agricultural exemption which you might qualify for. Don’t even consider putting it up without a permit unless you are 100% certain it is exempt;

#6 The wall girts flat to the wind on the outside of the columns – they will overly deflect (again not meeting the Building Code);

#5 Plywood gussets on the trusses – even if your seller has the engineered drawings for them, they are not going to meet the current Building Code;

#4 There is no lateral truss bracing – as the trusses are on each side of the columns are acting as single trusses. At a bare minimum, they will need a row of 2×4 “T” bracing no more than 10 feet on center;

#3 The wood framed sliding door is going to be heavy – and it probably has square barn door tracks. You may want to replace it with a steel framed sliding door and a round track so it is light enough and easy enough to roll open and closed;

#2 Sure hope you can get all of the steel back in the exact same places – because if you are unable to, there is a good chance you will experience roof leaks;

And the #1 reason – For about $3,000 more, you could get a brand new post frame building designed to meet the building code, with all new materials, delivered to your site, with all colored steel roofing and siding PLUS engineered plans!

Is Galvanized Steel Siding an Eyesore?

Like many things, beauty is in the eye of the beholder. I recently saw a photo of a McMansion in Florida, valued at eight figures, with a galvanized steel roof. Personally, I thought it looked pretty darn nice (as did the architect, builder and home owner apparently).

What got me going on this subject was a recent blog posting in the “Ask The Mayor” column of the Aberdeen (South Dakota) News:

Galvanized Steel Screws“Q. What can we do about a home in our neighborhood that is a disgrace? There are no gutters, the deck fell off and now we hear the owner plans to put up ugly galvanized steel siding just like on a pole barn.

 Is there an ordinance that will prevent this owner from doing something that will be an eyesore for the whole neighborhood? Are there rules about what kind of siding can be used?

A. When the building permit is applied for prior to starting a siding job, the applicant has wide latitude in the choice of type, color and design of the siding. There is no specific prohibition of this particular siding choice in the building code.

 Why not? As has been noted before in this column, the city building codes consider property rights as a major consideration when balancing aesthetics with freedom of action.

 That leaves it open, for example, for a person to paint their house any bizarre color. Home designs have great latitude to be wildly unconventional as long as they stay within the safety and minimum construction standards.

 Does that leave neighbors with any alternative? One possible avenue is the city nuisance code, which lists things which are prohibited because they are contrary to the general welfare.

 Among those nuisances is listing number three in section 28-118 of the city ordinance book:

 No person shall do something which “Does or tends to lower the value of adjacent real estate because of unsightliness.”

 If you are living next door and having to look at what you consider an eyesore every day, this language appears to be definitive and easily applied. But, it isn’t an easy determination to make; it’s hard to prove and could be challenged by the property owner. It is more typical for these disputes to be resolved by civil court action (or threat of action) rather than by government imposition.

 An issue regarding unsightly, galvanized siding in residential areas has not come up, probably because it is contrary to an owner’s interest and would lower the value of their own property. Now that this project is apparently a looming threat to this neighborhood, neighbors can ask for an evaluation as to whether the nuisance code application is justifiable.

 The question sent in did not specify the exact address in question. If the property owners in the area feel compelled to take action to stop that siding project, they should contact the city planning and zoning department, make their concern known, and file their complaint.” 

There are many architectural instances where galvanized steel siding (“just like on a pole barn”), is not only used, but is specified by the architect. I’ve supplied 22 gauge 2-1/2 inch corrugated galvanized steel for a mansard facing of a downtown hotel in a major metropolitan city. The hotel was considered a historic building and the refurbishing had to be done, to essentially match what had been on the structure for nearly a century.

Personally, I feel the mayor’s opinions are spot on!

Galvalume ®

Galvalume SteelMy first exposure to Galvalume ® was when ASC Pacific introduced “twice-the-life” Zincalume in the 1980s. They were marketing the product in its bare (unpainted) form as an alternative to the more familiar bare galvanized sheet steel. It looks similar to galvanized steel, but the visible crystals (or spangle) are smaller and close together, giving it a smoother appearance.  The combination of zinc and aluminum enhances both the positive and negative effects of aluminum.

Because aluminum is corrosion-resistant, Galvalume is more corrosion-resistant than galvanized steel, but because aluminum provides barrier protection instead of galvanic protection, scratches and cut edges are less protected.
Most consumers are familiar with old barn with bare galvanized steel panels which rusts (oxidizes) red. Bare Galvalume steel panels are not bright and shiny when new, unlike galvanized panels. As Galvalume ages, it oxidizes white. One prolific builder in the Pacific Northwest was actually even selling the product as a white roof!

Galvalume is a sheet steel with a hot dip applied alloy coating of about 55% aluminum 45% zinc. It is manufactured and sold as a trademarked product by companies such as Bethlehem Steel and National Steel.

I did find out, (the hard way) there are some limitations to uses of bare Galvalume steel panels. When the product first came on the market, we provided it as roofing for a building which later became a hog confinement barn (unbeknownst to us). The client called within two years of the roofing being installed, to complain about fist sized holes developing in his roofing. According to the roll former, It turns out the Galvalume coating had a chemical reaction to the confined urea, which basically “ate” holes in the steel. For this reason, Galvalume is best not used in animal confinement buildings.

Prepainted Galvalume roofing and siding panels are now used on buildings everywhere. It combines well with most other building materials and treatments. As such its versatility allows it to be used almost anywhere on building exteriors. Its excellent corrosion resistance has been proven by field performance on buildings for decades. An estimated 40 billion square feet of prepainted Galvalume sheeting covers buildings in all kinds of climates and environments in North America, Europe, Asia and Australia. The combination of long-lived Galvalume sheet with a wide range of modern high-performance paint systems results in a functional, durable, eye-appealing building product.