How To Insulate A Metal Building: New Structures, Retrofitting, Best Types Of Insulation + Recommendations

The number of pre-engineered steel buildings in the US continues to grow and now constitutes 65% of commercial low-rise projects and 95% of industrial new constructions.

This increase means an expanded demand for metal building insulation options.

If you’ve ever spent time in an uninsulated metal building, you’re likely familiar with the extreme temperatures that can result.

Without an insulation barrier, metal buildings can become scorching hot in the summer and blistering cold in the winter.

Insulating your steel building not only provides weather protection, it also offers noise protection, proper ventilation, reduced energy costs and more.

Here, we will provide you with a detailed guide on how to insulate a metal building for both new and existing structures, plus the types of insulation we recommend and tips to keep your steel structure condensation-free.

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How To Insulate A Metal Building: Types Of Insulation

The most common options for metal building insulation include reflective foil, fiberglass, insulated panels, rigid boards and spray foam.

Each type has its advantages and disadvantages, and considerations include budget and performance expectations.

Based on our 18-year technical expertise, we recommend the use of Prodex for your metal building insulation.

Why Prodex?

In contrast to the more traditional insulation options, Prodex is a new generation material that serves as an all-in-one insulation solution.


  • Has a reflective reinforced foil structure with a closed-cell polyethylene FOAM center
  • Prevents radiant heat transfer by up to 97%
  • Blocks condensation
  • Has an R-value that is not affected by humidity or compression
  • Is fire-resistant
  • Has a rippled surface that adds to increased airflow
  • Seals well around nails and does not allow leakage
  • Does not decay over time
  • Acts as a vapor barrier
  • Prevents the nesting of rodents, bugs and birds
  • Prevents the growth of mold and mildew
  • Is eco-friendly

When it comes to metal building insulation, we recommend Prodex 48 Inch, Fast Action, 72 Inch, 10M and White Prodex Total.

Each of these types provide improved tearing resistance, zero-index flame spread and an R-value between 15.3 and 22, while the reflective reinforced foil on each side ranges from 5 mm to 10 mm.

Let’s look at some of characteristics that differ between types.

Prodex 48-Inch and Prodex Fast Action are similar in characteristic features but the latter provides additional adhesive running of 175 ft on one side of the roll to seal the seams. If you opt for Prodex Fast Action, you will not need reflective tape and you will save time and money during the installment.

Prodex Total 10M Plus has cuts at the edge to overlap the rolls. A hot air gun and light hand pressure will ensure the melting of the polyethylene foam and a complete welding process. The result will be waterproof overlapping and a mechanical seal between the installed rolls.

White Prodex Total has an additional UV-resistant white facer and is ideal for applications where white facing is preferred, while Prodex Rustic provides an attractive wood finish.

Should you decide to opt for insulation options other than Prodex, we recommend using Foil Fiberglass Vinyl or Reflective Bubble Reflective. They are suitable for both new installs and existing metal buildings and are durable and affordable.

Foil Fiberglass Vinyl is made of ¼ inch fiberglass encapsulated core in one layer of 99% pure aluminum and an additional layer of durable white scrim-reinforced facing material. It is the preferred option where a white facing effect is desired.

Reflective Bubble Reflective consists of one layer polyethylene bubble pressed between two metalized low emissivity surfaces. It functions as an effective thermal break and reflects up to 96% of radiant heat.

Note that neither Foil Fiberglass Vinyl nor Reflective Bubble Reflective cover all metal building insulation issues the way Prodex does.

Not sure what type of insulation to choose? Contact us!
Not sure what type of insulation to choose? Contact us!

Metal Building Insulation: Equipment Checklist

The installment process with Prodex is fast and easy and does not require many specific tools.

We have prepared a short list of the needed equipment which may vary according to the type of Prodex you choose.

The equipment checklist includes:

  • Reflective tape
  • Double sided tape
  • Super metal sealant
  • A utility knife
  • A screw gun

Reflective tape used to keep the insulation layers in place or patch reflective insulation. It is effective in high and low temperature extremes such as sub-zero cold, dry or tropical temperatures. It creates a vapor barrier and can help improve the effectiveness of insulation. Unlike traditional duct tape, it is UV-resistant, does not delaminate or break down over time, and offers easy application and superior performance.

Double sided tape keeps the insulation from blowing during the installment process and helps attach insulation to the surface and seal seams.

Super Metal Sealant is used to attach insulation to any surface including steel, aluminum, pained metals, galvalume, wood, fiberglass, fiber-reinforced plastic and concrete. It acts immediately to hold insulation up on a vertical surface without the need for fasteners such as nails or staples.

Super metal sealant needs 60 minutes to set up. It improves the R-value of insulation by eliminating holes that may appear as a result of fastener application.

The utility knife is used when you need to cut insulation according to certain measures while the screw gun comes in handy when you deal with fastening, to ensure continuous insulation without leaving any metal part exposed.

How To Insulate A Metal Building: New Install

Below we will share our step-to-step guide on how to insulate your new metal building. Applying Prodex is fast and easy and you will only need your equipment kit and the roll of your chosen type of Prodex.

Use our Insulation Calculator to receive an estimate on the amount of insulation needed for your metal building.

New Install Roof And Wall Insulation Over Purlins

For this purpose, you can choose from our Prodex assortment — Prodex 48 Inch, Fast Action, 72 Inch, 10M, White, Rustic or alternative insulation options such as Reflective Bubble Reflective or Foil Fiberglass Vinyl.

  • Apply double-sided tape on the top of the purlins to prevent insulation from blowing in the wind.
  • Roll the insulation perpendicular to and over the purlins.
  • Allow the insulation to sag at least two inches. This will ensure the trapping of air, which will serve as an additional insulation layer.
  • Use reflective tape to fix the seams. If you are using Prodex Fast Action or 10M, you will not need to do this because of their additional adhesive that performs the same function.
  • Attach your sheeting.

New Install Roof And Wall Insulation Over And Under Purlins

For this purpose, we recommend the use of Prodex 48 Inch, Fast Action, 72 Inch, 10M, White or Rustic.

Steps 1 to 5 remain the same as in the above instructions.

  • Glue a second layer of Prodex to the underside of the purlins using our Super Metal Sealant.
  • Apply the insulation perpendicular to the purlins. If you are using a 48-inch-wide-roll, the width between the purlins will not matter.
  • Reinforce the insulation attachment by banding or screwing every four feet.

How To Insulate A Metal Building: Existing Structure [Retrofitting]

Insulating an existing metal building is known as retrofitting and it can refer to structures with or without prior insulation layers.

You can use Prodex 48 Inch, Fast Action, 72 Inch, 10M, White, Rustic or alternative insulation options such as Reflective Bubble Reflective or Foil Fiberglass Vinyl.

  • Use Super Metal Sealant and double-sided tape to attach the insulation to the purlin underside surface. Run the tape and glue adjacent to each other to ensure short-term and long-term stable hold.
  • Double sided tape
  • Super metal sealant
  • A utility knife
  • A screw gun

An extra tip: Many builders cut 1” x 2” metal pieces and use those to screw through and reinforce the installed insulation.

How To Avoid Condensation In Steel Buildings

In steel buildings, condensation appears when warm air comes into contact with the cold metal surface. Condensation can be visible or concealed.

If visible, it can be seen in the form of water, ice or frost on surfaces, including cooling ducts and cold pipes.

If concealed, it takes longer to notice and eventually it shows in stains and wet spots on ceilings and walls, along with peeling paint or bubbles on surfaces.

Condensation can provoke the growth of mold and mildew, and consequently health issues, along with the nesting of insects, unpleasant odor and structure corrosion.

Here are some tips how to keep your metal building condensation-free:

  • Make sure there is good air circulation at all times. If there are additional sources of moisture such as plants or propane heaters, use fans to facilitate evaporation.
  • Install quality ventilation systems or check yours to ensure they are working properly. Add ceiling vents to lead hot moist air directly outside.
  • Check lighting to ensure it is not generating heat. Heat build-up can lead to additional moisture.
  • Implement an efficient drainage system and lead the water away from rain and melting snow.
  • Use dehumidifiers in areas with moisture concentration.
  • Seal insulation ends and cover joints and seams to block moisture reaching the insulation layers, especially if you use insulation that experiences affected performance when it gets damp (like fiberglass).
  • Always apply insulation in a continuous mode and do not leave metal parts exposed as they will facilitate heat transfer and condensation.
  • Apply insulation on both the walls and roof of your steel building to eliminate vulnerable areas and create an overall healthy environment inside.
  • When possible, use high-quality insulation that simultaneously blocks condensation and serves as an air and vapor barrier. Such insulation options, like Prodex, will ensure the optimum performance of your metal building.
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