Why Is My Metal Building So Hot or Cold? A Complete Guide to Fixing Temperature Problems

 Enter an uninsulated steel building in July and you know you've walked into an oven. Enter the same building in January and you've entered a freezer with dripping water on your head. Steel is exceptional as a building material in that it is strong, quick to erect, doesn't decay, and is uninhabitable to termites. It is terrible in its abilities as a thermal barrier. The metal building pulls in the heat when the sun beats down on it and dumps it out the minute the evening chill sets in.

This problem is why so many people have regretted investing in a bare metal shell, saving the cash for the next fifteen years only to spend it on heating and cooling their warehouse or farm. Metal building insulation is what turns a steel box into a place of work, storage, or habitation. Without it, you are simply paying to heat the outdoors.

Shops where the workers wore coats indoors during winter were common places where the winter propane bill ran into thousands of dollars. The inconvenience is not a small matter. Metal building insulation can help address the insulation and thermal performance issues that affect steel buildings.

What Exactly Does Insulation Do Inside of a Steel Structure?

Insulation slows the movement of heat. In short, that is its entire function. Heat will always look to move from warm areas to cooler areas and insulative materials make this process occur at a slower rate.

In the winter, this slows the loss of your heated air. In the summer, it slows the infiltration of solar heat into your building. With steel, a second major concern is addressed by insulative materials and that is moisture control. Warm, moist air contacting a cold surface will always cause condensation. Much like a cold glass of lemonade sweating on a porch table, this causes moisture to collect on the interior of a steel building. This indoor "sweat" can ruin equipment, soak stored goods, rust fasteners, and promote mold growth. An effective vapor barrier or facing on your insulation for metal building projects keeps this warm, moist air from ever reaching the cold metal.

You get temperature control, moisture control, and some noise dampening as well with proper insulation for a steel building. Rain on a bare metal roof sounds like someone emptying a bag of gravel over a drum, while insulated reduces this to a dull slap.

What Types of Insulation Are Actually Effective for Metal Buildings?

There are several options and they are not all created equal. Fiberglass blanket, the old standby, is available in a rolled form with a vapor barrier facing of vinyl or foil. Its installation is simple and it is an economical choice. This type can sag, become compressed, and if the facing is compromised offer no moisture protection. It is everywhere for good reason.

Spray foam, the other popular choice, adheres to the underside of the steel, sealing gaps, adding rigidity, and offering a high R value per thickness. It is a more expensive option with no room for negotiation. Open cell is lighter and cheaper but differs in its reaction to moisture, making it less desirable for use on steel panels. Rigid foam boards, reflective radiant barriers, and insulated metal panels which contain the foam within are other options.

Radiant barriers are an interesting choice in hot climates as they reflect solar heat rather than resisting its transfer. They offer little benefit in colder climates such as Minnesota, and no benefit at all in subzero weather. The climate a building is located in is an important consideration when choosing between products, and anyone claiming one product is superior in all climates is likely trying to sell something.

How Do You Calculate the Correct R-Value?

R-Value is simply a representation of a material's resistance to heat flow and is measured in numbers with higher being better. Beyond a certain point, increasing the thickness offers diminishing returns while also increasing the cost exponentially.

The climate the building occupies dictates most of what you need to know. A structure in southern Arizona has vastly different needs than one in northern Montana. Roofs take a higher priority as a surface exposed to the sun and will typically have a higher R-Value than walls. Typical values range from R-19 to R-30 for roofs and R-13 to R-19 for walls, but local codes may dictate otherwise. Always check with your authority before purchasing insulation material.

The use of the building also informs the choice. A barn meant for storing hay has vastly different requirements than a heated workshop, gym, or office. Consider the building's future use as well as its immediate future, as ripping out insulation is a hassle no one looks forward to.

What Does Metal Building Insulation Cost and Is It Worth It?

Prices vary wildly, fiberglass blankets installed can range from about one to two dollars per square foot. Spray foam ranges from two to five or more depending on thickness and contractors. Insulation for metal building is the most expensive but come with the wall system as well, so they aren't truly comparable.

Generally speaking, properly installed insulation reduces heating and cooling costs by a large margin, up to fifty percent in some cases. Doing the math on a building which costs several hundred dollars per month to condition can show a payback period of only a few years. Protection of inventory is another factor, as is the prevention of the slow, costly decay process caused by condensation within the building.

One note of caution, do not fall for the cheapest installers. The quality of an installation done on the cheap with large gaps and torn vapor barriers is exponentially worse than one done properly at a higher price. I would choose a mid-range installer who does a competent job over a budget one who shortcuts the job any day.

Should You Install It Yourself or Hire a Pro?

It depends on what you buy and what you are willing to do. A fiberglass blanket over purlins is an easy weekend project for a couple of people. It is itchy work and not particularly easy at height, but the seams must be taped or the vapor barrier is compromised entirely. If not experienced, watch a couple of installations before attempting it yourself. The promotional videos on the manufacturer's website rarely resemble the project at hand.

Spray foam should be left to the professionals, it's far too dangerous for an untrained worker. The products need to be mixed at a ratio that cannot happen without the proper mixing equipment, incorrect ratios can cause failure, odor issues, or poor adhesion. It also requires proper safety equipment, and ventilation in order for the job to be done right, something an amateur could have trouble with. Avoid purchasing the DIY spray foam kit for a large job.

Whatever method is chosen, vapor barriers should be planned with care. Their location, sealing, and taping at edges and penetrations is vital to an effective job. Small leaks around doors, vents, or eave struts allow air in or out and undo much of the effort.

What Are the Most Common Mistakes People Make?

Failure to use or install a vapor barrier, assuming that any insulation is adequate, and leaving it hanging loose are rookie errors. Condensation will always seek out a place to occur, and having a warm, moist area with a cold surface nearby is an open invitation to water damage. Sagging or compressed fiberglass loses much of its effectiveness and is a waste of material and money.

Failure to ventilate a conditioned or heated space is another common oversight. An insulated building which is home to vehicles, animals, humid processes, or people still requires some form of ventilation to remove excess moisture from the air.

Doing the roof but not the walls and slab edges is another frequent error. Heat escapes through every weak point, and doors, overhead doors, windows, and slab edges are all weak points. Sealing and insulating the entire building envelope is critical to getting the most out of the job. Thermal bridging, the conduction of heat through steel framing, is also a factor. Thermal breaks or interrupted layers of insulation are solutions.

How Do You Maintain It So It Lasts?

There is not much to it, really, but nothing is a good idea. Annually check the insulation for sagging, moisture and torn vapor barriers. Mice have a way of nesting in the fiberglass insulation and that should be taken care of as soon as it's noticed. Wet insulation should have the source of the leak located and repaired as soon as possible due to the fact that it's effectiveness is greatly reduced and that it encourages the growth of unwanted and hazardous materials.

Leaky roof areas and flashing should be checked and repaired. Faulty screw gaskets can saturate an area of blanket insulation in just a matter of hours. Remove and replace that affected area before it becomes a big problem.

Good insulation for metal buildings should last twenty-five years or more if it's installed correctly and kept dry. Spray foam in particular can outlast the roof panels. The real work is in the installation and a good job from the start prevents the need for future maintenance.

Conclusion

Steel buildings are incredibly useful structures that can withstand much abuse. The right plan using the right material, R-Value, vapor barrier, and ventilation yields exceptional comfort, decreased utility costs, and increased life of the building. Metal building insulation is not a luxury addition but a fundamental part of constructing a steel building. Those not sure what to do or who can do it right should begin the conversation with Metal guard once. It is the right investment to make once and be done with it for years to come. 

FAQs

What is the best insulation for a metal building?

It depends on the climate and use and budget. Fiberglass blanket offers economy, closed cell spray foam offers performance, and insulated panels offer both.

How do I stop condensation in my steel building?

Use a sealed vapor barrier with fully insulated walls and roof. Spray foam placed on the underside of the panels also prevents the "cold spot" needed for condensation to occur.

What R-value do I need for insulation for metal building roofs?

The majority are between R-19 and R-30, though colder climates may need more. Check with your local code officials.

Can I insulate an existing metal building?

Yes, spray foam can be applied directly to metal surfaces. Blanket or rigid insulation can often be retrofitted with some framing as well. It isn't nearly as difficult as you might think.

How much does it cost to insulate a steel building?

It can range from about one to five dollars per square foot, depending on materials and thickness.

Is spray foam better than fiberglass for metal buildings?

Spray foam tends to be better as it seals gaps and adheres to the metal, preventing the usual problems with fiberglass. Fiberglass is lower cost but should be installed with great care to the vapor barrier.

How long does insulation last in a metal building?

Properly installed and maintained, it can easily last twenty-five years or longer.