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3 Tips to Help Prevent Pole Barn Rust

May 2nd, 2017 | 12 min. read

Angie Dobson

Angie Dobson

Angie graduated from Indiana State University with a Bachelor of Science in Interior Design. Prior to joining the FBi team, Angie was a kitchen and bath sales consultant in Lafayette, IN. In 2012, she started with FBi as the Inside Sales/Marketing Assistant. Today she holds the role of Sr. Marketing and Inside Sales Manager. Angie grew up in a farming community and has always enjoyed helping her family on the farm. A past 10-year 4-H Member, her passion for livestock pursued her to take a career in the agriculture field. She and her husband live in Northwest Indiana with their two daughters. In her free time, she enjoys outdoor leisure activities and spending time with friends and family.

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As you pull into the driveway, you can’t help but marvel at your 66' x 120' x 16' farm shop. The overhead and sliding doors make it a breeze to move agricultural equipment in and out. The heated workshop is convenient when servicing your machinery during the slow winter months.

Over the years, you’ve worked hard for your pole barn. As a farmer, it takes sacrifice, blood, sweat, and tears. In return, your post frame building has worked hard for you.

Unfortunately, it’s starting to show its age with a little rust on the steel siding. It's probably the last thing you want to deal with, but if you don't take care of it now, it'll continue to worsen.

Your first reaction is to freak out (and understandably so). As you run your calloused fingers along the tarnish, you can’t help but wonder, “Why does my pole barn rust?”

Despite being one of the most common and useful manufactured materials in the world, steel has one major flaw...it rusts. Why steel products erode in the first place makes for an interesting topic. In this article, we’ll also discuss proactive and reactive steps to handling pole barn rust.

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What is Rust?Pole Barn Rust

Rust is a form of iron oxide, which occurs when iron and oxygen cause corrosion. It appears in a variety of colors, including:

  • Red
  • Brown
  • Orange
  • Yellow
  • Green (Don’t believe us? Google it.)

The different shades reflect various chemical compositions. Rust refers to the oxides on iron and its alloys (e.g., steel).

The main culprit behind rusting is moisture. Although metal looks impermeable to the naked eye, water molecules gain access through microscopic gaps.

This infiltration is the first stage of corrosion. Exposing your post frame structure to carbon dioxide, salt, and sulfur dioxide will speed up the process.

Rust causes the metal to expand, which places a great deal of stress on the building. Meanwhile, the steel sheet is weakened; thus, becoming brittle and flaky. 

As mentioned above, rust feeds off air and water. Any metal layers beneath the tarnish will continue to oxidize.

Pole Barn Repair Quote_FBi Buildings

3 Tips to Help Prevent Pole Barn Rust

Pole barn rust is inevitable, but there are a few preventative measures you can take to postpone corrosion. 


1) Use Rust-Resistant Alloys

Steel Panels_FBi BuildingsPopular examples of rust-resistant materials include galvanized and galvalume steel.

First, galvanized metal is a steel sheet that has been coated with a thin layer of zinc oxide. This chemical element protects the steel from hash components that can cause corrosion. 

Eventually, the zinc layer will fade. Now, you’re probably thinking, “Wait a minute, isn’t that bad?”

Remember, having zinc deteriorate before the metal layer is what protects it from rust. Subsequently, the steel sheet will weaken and break down within 10 to 15 years of direct element exposure.

Secondly, galvalume is a steel sheet coated with aluminum-zinc alloy by a continuous hot-dip process. The coating consists of 55% aluminum and 45% zinc, with a small dose of silicon.

However, the silicon additive has nothing to do with corrosion performance. Instead, it provides adhesion during metalworking.

The alloy coating of aluminum and zinc combines the best properties of both elements. The end result is a coating that’ll last a while. It outranks galvanized steel in terms of comparable thickness and cutting-edge protection (fewer stains).

At FBi Buildings, we use galvalume-coated steel for our post frame buildings (roof and siding). Galvalume battles rust 2x to 4x longer than galvanized steel. If needed, we’ll use galvanized metal, but we’ll use a heavier coating so it’ll last longer.

Overall, galvanized and galvalume metals are a significant investment in delaying pole barn rust.


2) Consider Your Building Design

During the design process, you’ll need to consider building features that’ll control moisture levels.

Condensation occurs when warm, moisture-laden air contacts a cooler surface, such as the underside of your roof steel. Since lower temperature air cannot hold as much moisture as warmer air, the excess humidity turns into water droplets. Then...drip, drip, drip!

Aside from rust, moisture can cause the following damage:

  • Mold growth
  • Lumber decay
  • Poor human/animal health
  • Discoloring of equipment and furniture

There are several ways to reduce condensation risk, and it starts at the beginning of your post frame project. Below, we detail the five components to proactively managing building moisture.


Site Preparation

Site Preparation_Perimeter Access_FBi Buildings copyProper site preparation is the cornerstone of condensation control. The objective is to set your building on a solid surface and to establish the right finished floor elevation (FFE), so your structure stays high and dry.

Typically, the first step in site prep is to remove all humus and sod. If this organic matter is not removed, it will decompose, causing your concrete or asphalt to settle and crack.

Fill should be applied one layer at a time and compacted to ensure a non-settling crowned surface. A layer of coarse stone over the soil base creates a capillary break and helps drain water away.

Poor groundwork can create capillary action and lead to serious moisture problems inside your building.

If fill material was added to your site, it likely contained moisture. The wet fill material can hold up to 15 pounds of water per cubic foot. This can take at least six months or more to dry out completely.

Although site preparation costs a little more upfront, it’ll save you money (and headaches) in the long run. When done right, your building will last longer, need less maintenance, and require less energy to heat/cool.

Site Prep, FBi Buildings


Now that your building is set high and dry, you should consider having gutters and downspouts installed. Most pole barn builders will offer these standard features. 

Proper drainage helps you manage the water flow that’ll come off the roof and send it away from the structure to a location of your choice. Many customers choose to run their downspouts into tiles that drain into remote ditches or ponds. Wherever you go with it, the key is to channel rainwater runoff away from your building.


Other Moisture Surfaces

Other factors that can increase interior humidity, and thus condensation potential, include:

  • Livestock (e.g., horses and manure)
  • Non-vented furnaces
  • Propane heaters
  • Greenhouses
  • Thawing snow from vehicles
  • Water puddling at the exterior perimeter of the building

Always remember that sources of moisture are additive, so even small sources can add up to a problem. Sometimes the source of moisture is inside the building.

The most common, although temporary, the problem is concrete. Freshly poured concrete is 16% water. As it cures, that water is released into the inside air. It does so at a rate of .1 pounds of water per square foot per hour (in an enclosed, wind-free environment).

This rate drops as concrete cures; concrete is substantially cured within one month of being poured.

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Next, ventilation goes a long way towards accomplishing condensation control.

Overhangs with ridge vents at the roof peak pull warm, moist air out of your pole barn and replace it with fresh air, dry air.

Adding a cupola to your structure will allow a way for trapped heat to escape through the fan and side vents. For a personalized touch, you can top it off with a weathervane.

Also, doors and windows provide ventilation, but that requires somebody to monitor the situation and open/close them as needed. 

Mechanical ventilation controls the air movement by using one or more ceiling fans. It isn’t commonly used for post frame buildings because it increases initial, operating, and maintenance costs. 

Depending on the location, site issues, and intended use, ventilation alone may not be enough to keep condensation at acceptable levels.


Barrier Options

OSB with Felt PaperFurthermore, roofing backer options are an additional way to help manage condensation.

It’s important to note that these options are supplemental to other preventative measures discussed above. 

There are five types of barrier options that we recommend for our post frame projects:

  • Thermax Insulation
  • Vinyl-backed Insulation
  • OSB with Felt Paper on Top
  • MoistureLok
  • Bubble Wrap Insulation (also known as Radiant Foil)

Again, these products can condensate, so they should be used in addition to other moisture materials.

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3) Perform Regular Maintenance

Unless you’re going for the “rustic chic” look, regular maintenance is strongly urged to prevent or halt rust formation. 

Power-washing your pole barn to remove dirt or debris will help with rust prevention. Please keep in mind that anything with water retention capabilities will likely cause steel corrosion.

If your storage building is showing signs of decay, it’s crucial that you remove the rust. You can treat the tarnished areas with a traditional sander, wire brush, or chemical remover. The goal is to create a smooth surface.

Don’t forget to remove grime with soap and warm water. Avoid strong solvents on previously painted structures. 

Apply metal primer to the stained spots. After 24-hours, you can paint over it with your desired color. Voila! Your steel siding looks as good as new.


Will You Be Able to Prevent Rust with Your Pole Barn?

As an owner, pole barn rust is a major disappointment. Although corrosive metal is unavoidable, you can utilize different building features to prolong it. Maintaining your steel structure goes a long way too.

In some cases, the damage is already done. Your pole barn looks like a weathered prop from a “wild west” movie set. Don’t panic! Our Repair & Renovation team will be able to restore your post frame building to its pristine condition.

Best of all, it doesn't matter who built the original structure. We'll make it look good as new!

Pole Barn Repair Quote_FBi Buildings

Do you have more questions about pole barn rust that are not covered in this article? If you need help designing and planning, please contact FBi Buildings at 800.552.2981 or click here to email us. If you are ready to get a price, click here to request a quote and a member of our customer engagement team will help you determine the next steps of your project.