Tag Archives: galvanized steel

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.