Tag Archives: polyiso

Cold Storage Pole Barns

Post Frame Cold Storage for Fruits and Vegetables

Hansen Pole Buildings’ Designer Rachel passed along this:

“Have a client call in asking if we have experience in designing a building for cold storage.  Confused I said yes, many building are used for cold storage and are not insulated or heated.  He said no I mean COLD storage as in storing fruits and vegetables in 36 or 38 degrees.  He is wondering what we would suggest for insulation and what he should consider when designing the building.”

Detached cold storage buildings are constructed with a sole purpose of producing or storing goods in low temperatures. Think of them as typical heated buildings turned inside out. Instead of keeping heat in during cold weather, they keep heat out during warm weather.

Condensation problems can be huge, if not properly dealt with. Adequate and totally sealed insulation plays a huge part in preventing condensation. Exterior walls should have a Weather Resistant Barrier between framing and wall steel to allow moisture to pass out of wall. Dead attic spaces should be well ventilated with eave air intakes and ridge exhaust vents.

Among most critical consideration for cold storage will be selection of a method for insulating the facility. Effective insulation will minimize cold transfer to exterior and reduce operating costs. Recommended cold storage building envelope (shell) insulation values are R-30 in walls and R-40 for roof. Concrete slab should be insulated to R-20. Recommended method of insulation will be polyisocyanurate (Polyiso). Polyiso has an R value of approximately six to 6.5 per inch of insulation, so a minimum of five inches of Polyiso recommended for walls and 6 ½ to 7” in ceiling. It should be glued on, as through fasteners will transmit heat and condensation could form upon exposed heads. It is essential for joints to be sealed and a vapor barrier should be placed between insulation (insulation goes inside of framing) and wall girts and ceiling joists.

Failure to totally seal interior vapor barrier can result in Polyiso insulation gaining as much as 15 times its own weight from absorbed moisture.

Special consideration needs to be given to site preparation, in order to minimize possibility of frost heave.

Building access should be through a wide 14 foot tall insulated overhead door in each endwall. Industry standard storage bins are four feet square and three feet tall. Bins can be stacked five high, leaving room for mechanical equipment above with a 20 foot interior clear height.


Allowing space for equipment movement and free airflow around each stack of pallet bins approximately 215 pounds of product can be effectively stored for every interior square foot of building.

And there you have it…a cold pole barn!

Safety Concerns from the Heartland

DEAR POLE BARN GURU: Could you give me a cost of installation of spray foam insulation for an indoor horse arena that is 65 by 125 ft in size. 

Wanting to insulate under roof area only.  We are a faith based non profit 501 c 3. JACK in SAVANNAH

DEAR JACK: Thank you very much for your interest. Hansen Pole Buildings is neither a contractor nor an installer. For closed cell spray foam (which is what you want to have), you should expect to pay about a dollar, per square foot, per inch of thickness.

DEAR POLE BARN GURU: I found your web site and wanted to reach out to you. 

I provide free safety consultation services to small employers in Ohio.  I have a small framer who does Pole Barns and he was cited by OSHA.  He needs a written Safety and Health program that addresses all of the applicable topics to this trade (Fall protection, Electrical and Ladder safety, PPE, tool safety, etc.)  I have never written a program for a contractor who does this type of work and was wondering if you could suggest any other links or resources that could help me with putting one together for me.  He is Amish and has no computer resources so I feel I need to do what I can to help.  I especially need some guidance with regards to Fall protection during the building process (tie off points, what can be used as an anchor, truss erection, etc.).  Please provide what you can to me.

Thanks for your help. PAULA in PICKERINGTON

DEAR PAULA: I’d start with www.nfba.org, they are the trade association for the post frame (pole) building industry and should be able to either provide what you are looking for, or get you pointed in the correct direction.

DEAR POLE BARN GURU: Using foil faced polyiso in pole barn do I put shiny Side out or in and can I use it on celling or can I put it on purlins under roof build is already built. JERRY in Onawa

DEAR JERRY: The determination for which side goes in or out will be based upon the goal you are trying to achieve. If you want to reduce heat gain in the summer, then the shiny (aluminum) side will go out, if you are heating the space and want to reflect the heat back into the building, then shiny side in.

Reflective InsulationSome thoughts – whether installed under the purlins or as a ceiling across the roof truss bottom chords, you have created a dead air space above the insulation boards which must be ventilated from eave to ridge or at the gables in order to prevent condensation, mold and mildew issues. In order to function properly, all joints and seams must be sealed tightly.

Before installing any product which will be supported by trusses, confirm they have the load carrying capacity to support it.

Many Building Departments require any foam sheathing to be fire separated from areas where humans will occupy. This could add to your expense.


Reflective Radiant Barrier Wars

Martin Holladay recently wrote an article for GreenBuildingAdvisor.com entitled, “Stay Away from Foil-Faced Bubble Wrap”.

Note that for the purposes of this blog, my comments are heretofore in bold.

I have no issues at all with a Reflective Radiant Barrier, as long as it is sold for what it is, and not wrongly represented. In pole building construction, reflective radiant barriers provides an excellent condensation control, having a very low perm rating, as well as a thermal break created by the air cells sandwiched between the exterior surfaces.

Here are some excerpts from Martin’s article:

Foil-faced bubble wrap is a thin product that comes in a roll.

Its R-value is dismally low.

Reflective Radiant Barrier

Most brands of foil-faced bubble wrap are only 3/8 inch thick or less, and have an R-value of only 1.0 or 1.1. Since the product often costs more per square foot than 1-inch thick rigid foam rated at R-5, why would anyone use bubble wrap as insulation?

The R-value of foil-faced bubble wrap is so low that it has few, if any, advantages over rigid foam. Of course, the product’s foil facing can be used as a radiant barrier — but if you want a radiant barrier, cheaper products are available. (The bubble wrap layer is unnecessary, since it adds cost to the material without adding any useful thermal performance.)

Now (in my humble opinion) Martin apparently does not know much (if anything) about how pole buildings are constructed. When rigid foam is placed between roof purlins and roof steel, the inch or more of thickness of the rigid foam boards creates an area where screw fasteners from the steel roofing can bend, I would not count on the ability of a roof system so constructed to have anything other than minimal diaphragm values.

Exaggerated R-value claims

Since the main benefit from foil-faced bubble wrap is due to its radiant-barrier facing, the product is basically worthless unless it faces an air space. A decade ago, when I was the editor of Energy Design Update, I noticed that many manufacturers of foil-faced bubble wrap were promoting their products for use under concrete slabs on grade. In this application, the shiny foil is clearly not facing an air space, so the exaggerated R-value claims made by bubble-wrap manufacturers were particularly outrageous. My article exposing the bubble-wrap scammers appeared in the September 2003 issue of EDU.

In that article, I reported that one manufacturer, WE International, made absurd claims about a thin (5/16-inch) product called Concrete Barrier rFoil. The manufacturer’s website boasted, “Concrete Barrier can serve three purposes underneath concrete: R-10 insulation, a vapor barrier and a radon barrier. … How does it compare to 2-inch foam board? It works just as well.”

Similarly, Insulation Solutions, the manufacturer of a 3/8-inch thick product called Insul-Tarp, claimed that the flexible tarp has an “R-value equivalent” rating of R-5 to R-10.

After these lies were publicized, three manufacturers wrote letters to EDU apologizing for the “oversights” and “typographical errors” that appeared on their websites.

Blurring the line between product R-values and assembly R-values

Many of the manufacturers and distributors that publish exaggerated R-values deliberately blur the bright legal line that separates product R-values from assembly R-values.

According to federal law, the R-value of an insulation product — for example, a piece of 1-inch thick polyisocyanurate — is the R-value of the insulation alone. That’s the R-value which insulation manufacturers are required to report on their packaging and in their advertising; the requirement is spelled out in the Federal R-Value Rule, a law that applies to manufacturers, retailers, and builders.

The R-value of a building assembly is something different. For example, if you build a wall with a layer of interior polyisocyanurate, followed by horizontal 1×4 strapping and drywall, the air space between the polyiso and the drywall has a measurable R-value. If you want to calculate the R-value of the entire wall assembly, you would need to calculate the R-value of the air space and add that R-value to the R-value of all the other layers. Once you’ve done that, you’ll know your wall assembly R-value.

Here’s the key point: polyiso manufacturers can’t claim the R-value of an air space in their labeling or advertising (unless the advertising makes a very clear distinction between the product R-value and the R-value of a hypothetical building assembly).

Product distributors are violating federal law

Fortunately, most (but not all) manufacturers of foil-faced bubble wrap have removed the blatant lies from their websites. Instead, manufacturers tempt the unwary with vague promises; for example, they claim that their bubble wrap “has a high R-value” or that it “resists the transfer of heat.”

The scoff-law websites with the greatest number of lies about foil-faced bubble wrap are those maintained by distributors — including a few large corporations like Home Depot, Ace Hardware, and Amazon — rather than those maintained by manufacturers.

For example, Amazon claims that a type of foil-faced bubble wrap product manufactured by EcoFoil (“HVAC Duct Wrap Insulation”) has an R-value of R-8. But a careful reading of the manufacturer’s technical data sheet and the referenced ICC-ES Evaluation Report reveals that the R-8 value claim is based on an assembly that includes the R-value of a 2-inch air space.

Similarly, Ace Hardware is advertising Reflectix, an R-1 foil-faced bubble wrap product, with a blurb that claims that the product has “R-values ranging from R-3.7 to R-21.”

(Your author happened to check at AceHardware.com and I can confirm Martin’s findings.)

That’s a little like Starbucks saying that a cup of coffee is a satisfying meal — as long as you remember to accompany the coffee with a 12-inch submarine sandwich (not included).

Yes, a few manufacturers are still lying

Although the major manufacturers of foil-faced bubble wrap have (almost) cleaned up their act, some still include exaggerations on their websites.

One manufacturer that trumpets exaggerated R-values is EcoFoil (a.k.a. rFoil, a.k.a. Covertech Fabricating). The EcoFoil website describes the company’s duct wrap as an R-8 product, even though the R-8 claim is based on an assembly that includes an adjacent air space.  

Considering the Use of a Reflective Radiant Barrier?

If so, invest in it for the things it DOES do well.

When installed with the reflective aluminum side facing outward, it does reduce heat gain from radiant energy.

When overlaps are properly sealed (rolls featuring a tab with adhesive under a pull strip work well for this), it can be an excellent condensation control.

If looking for R-value, consider the assembly. When an adjacent dead air space can be effectively placed in relationship to the location of the reflective radiant barrier, increased R-values can be created.

Another bad apple is Insulation4less, which retails a thin product called Prodex Total. On its website, the company states, “Prodex Total has a nominal thickness of 5 mm (13/64 inch) closed cell polyethylene foam covered on both sides with .0012 (00.03 mm) aluminum foil facing. … R-value R-16 unaffected by humidity.”

Prodex may be unaffected by humidity — but it is seriously affected by gross exaggeration.

These are not examples of victimless crimes; there are victims. One victim is a blogger reports using this sub-slab assembly: “In basement, install Insul-Tarp over crushed rock, single layer of wire mesh, and Wirsbro [hydronic] tubing, pour concrete (pump hose will go through stairwell hole).”

Unfortunately, Insul-Tarp has an R-value of R-2 or less. For years, however, the manufacturer of Insul-Tarp claimed that the product was rated at R-7 or more. The blogger who specified Insul-Tarp believed the false claims, which is why he wrote, “This is what the Insul-Tarp looks like. The exterior is some kind of tough fabric, then there are two layers of thin white foam, then a layer of bubble wrap. Hard to believe this can be equivalent of 2 inches of Styrofoam.”

Indeed, it is hard to believe — so hard, in fact, that the Federal Trade Commission initiated court action that forced Meyer Enterprises, the manufacturer of Insul-Tarp, to stop making false claims. According to the FTC complaint, Meyer Enterprises “claimed Insul-Tarp’s R-value is 7.54, but in reality Insul-Tarp’s R-value could not be more than 2.”

For the most part, I found Martin’s article to be educational, and as stated, you just have to read the fine print and use products appropriately.