Dear Guru: What Type of Insulation?

Pole Barn Guru Blog

DEAR POLE BARN GURU: Good morning, Mike … I have a question for you.

I’m trying to decide between a 30×40 barn and a 60×40 barn. It would have a gambrel roof with a loft. 16′ wide sliding door in the center of the short ends.

All other things being equal, what is the cost difference between 30×40 and 60×40?

Or is there a size that’s more economical?

Thanks, Mike T. in Kershaw, SC

DEAR MIKE T.: Having to design the loft to support hay weight is not so much of a challenge as it is expensive. For sake of discussion the comparison was done a full loft, however it may be more practical to only have the loft in the center.

There is an economy of scale with pole buildings. For practical purposes, the price per square foot is going to decrease as the building footprint increases (until clearspans become very wide). I’ve also never had a client tell me their new building is “just too big”!

In your particular case, you could double the size of the building, while increasing the investment by only about 2/3.

Mike the Pole Barn Guru

DEAR POLE BARN GURU: Renovating our pole building arena is an undertaking.  We were quoted $70k (which included windows to replace the plastic) so we are doing it ourselves. I expect materials to run about $25k in the end.  The company that sold me the metal ceiling panels based out of Kentucky told me that people in his area do it all the time and that the best way to go is with blown insulation, as fiberglass batting is a lot more time consuming to install.  I decided against spray foam because it is toxic to begin with and then they put fire retardants in the mix which is even more toxic.  Plus it is expensive.

What will happen if we don’t have a “thermal break” on the underside of the metal roof? There will be a lot of condensation falling on the blown insulation?  We have a roof vent which I guess is correctly installed because we never have water coming in even during the most violent and heavy of rain storms. Isn’t this vent enough to prevent condensation?

If a herd of animals lived in the building, then I would worry about condensation, but there will be maximum 2-4 live beings in there at one time.   Removing the roof to install a reflective radiant barrier is not an option.  How about covering the underside with “Tyvek” the stuff houses are wrapped in?  Are you saying the blown insulation on the ceiling will not do its job without this thermal break on the roof, or is it the condensation you are concerned about?   What does the reflective radiant barrier need to reflect?  Cold coming from outside, or heat coming from outside?

We have blown insulation in our 14 year old house.  I guess it is newspaper.  It works a charm.  We’re on a hill and it can blow out there and we’re cozy inside.  One can buy cellulose from Lowe’s or Home Depot and they lend you a machine to install it.   I was worried that wind from the roof vent would blow it around.  I was also worried critters would nest in it, although we have covered such access with 1/2″ wire mesh.  Nonetheless, critters are very resourceful about getting into things.  I was worried that if it got wet it would get moldy.  My daughter is very sensitive to mold.  Best thing is it stays dry….and like I said, we never had rain come through that vent, although when the conditions were right, we’d get a bit of snow blown in.  We have a lot of snow now, and no snow in the arena.  So it has to be special conditions. I thought of covering the blown insulation with tarps to protect it from wind or moisture.  Is that a good or bad idea?

BTW, we have no intention of heating the arena.  The goal is to have it warmer in there than outside….hopefully a little above freezing.

I guess for the walls we will use fiberglass.  The plastic panels will be replaced with double glazed “picture” windows (they don’t open) and will run the length of about 2/3 of the arena at 2′ high.

A trainer we met from Maine said he insulated his riding arena and it really helped keep out the cold.

I’m wondering what will happen in summer.  Will it keep out the heat, or trap it?

It’s great communicating with someone who knows what they are talking about.  I’d be happy to compensate you for your expertise.

P.S.  Here’s a fiberglass story.  The owner of a horse boarded at our farm had a plumbing leak in her basement.  The plumber came and fixed the leak and left.  Several weeks later she developed itching sores all over her body.  She woke up one morning with arms so swollen she could not bend them and a face twice the size of normal.  She went to the ER and they told her a dust allergy, so she threw out all drapes and mattresses, etc. and cleaned the carpet and whole place.  However, it didn’t help and she landed in the ER again.  Meanwhile they found out that the plumber had pulled away fiberglass insulation from the broken pipe, and because of the leak it was all wet.  He didn’t remove the wet fiberglass and so mold developed, and with the furnace down there blowing hot air (with the mold) all over the living space it made her VERY sick.  She moved out immediately and had to take a lot of nasty drugs, and she is still not well.  Plus, inhaled fiberglass is a known carcinogen, as you probably know.

A GREAT thing to insulate with is wool.  But who can afford it?  They do make wool “bats” for the purpose though.  CINDY

 DEAR CINDY: Without the thermal break under the roof steel, there will be condensation on the underside of the roof steel, which will result in rain upon the attic insulation. Ventilation alone may cure some, but not all of the condensation problems.

The major source of the warm moist air rising is the ground under your building (evapotranspiration). According to www.ScienceDirect.com the average value of the moisture evaporation with uncovered ground is 0.33 to 0.53 gallons per hour per square foot. For a fairly typical 60 by 120 foot riding arena, this could be between 57 and 90 thousand gallons per day!!

Housewraps like Tyvek are not vapor barriers – they are designed to allow moisture to pass through.

Reflective radiant barriers just happens to be a very cost effective thermal break. The aluminum facing on the exterior reflects radiant heat in the summer, keeping the building cooler.

Insulating your building will keep it cooler in the summer, there is no question there. As to the effectiveness for keeping things warmer inside, without a heat source the air inside will be at or near the temperature on the outside.

And thank you very kindly for your offer of compensation. I do my best to provide quality information for the good of the industry as a whole. If you feel I have been of service, please feel free to share the link to this blog with others.

Mike the Pole Barn Guru

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