Retrofitting Insulation for a Milking Parlor
Reader CALEB in SLEEPY EYE writes:
“Hello! So many questions! We have a simple 20 by 30 pole shed we are looking to retrofit into a cow milking parlor on one half and a general purpose/milk equipment cleaning area on the other half. We’ll pour concrete, insulate, and then install steel on the entire interior. We’ll also be removing the current sliding doors, framing in those openings, and adding man doors/windows (I’m hoping that will be fine to frame in on the slab and won’t have frost heave issues?) Currently, the exterior is just metal on wood, no WRB, no soffit or gable vents. The rafters do not seem very substantial and about 8 feet apart, so we are hoping to have a local design build figure out how we can beef them up to support insulation and steel ceiling (unless that’s something you guys can do?). My main questions at this point are with the insulation. I realize this is the age old question, but my hours of research have still left questions. I am hoping to insulate without rigid or spray foam because of price and difficulty of future repairs with spray foam. With foam board, there’s no more drying to the exterior and I would prefer that since this will be a substantial amount of humidity produced in this environment during milking equipment cleanings. Without using foam, it seems I would have to remove steel and install WRB if I hope to have a good air seal, correct? Once there’s a WRB, can I then just use 2×6 walls with fiberglass or mineral wool batts, or insulation blankets? Then vapor barrier, and then steel? This seems to still allow drying to the exterior which I would think to be a good thing. On cold days, will moisture that does make its way into the wall cavity still condense on the WRB? Or does it go through the WRB and condense on the back of the steel? I ask this to try and figure out how much it matters if I do fiberglass or mineral wool batts. As for the ceiling, after adding gable vents, would I be fine with just blow in fiberglass on top of the new flat steel ceiling? I am not sure how to address the condensation on the current roof steel without pulling all that up and adding the reflective insulation you mention in other posts, or spray foaming. I suppose all of that above could be summed up in the questions, what would be the best way to insulate a bare bones Minnesota pole shed without foam? And, if you think foam would make more sense to add, what would be the best way?
Thank you.”

By the time you get done retrofitting this building, you could start from scratch and build a new building for less. And – it would be exactly as it should be, not sort of like.
Assuming you are dead set upon utilizing this building….please read on.
Before pouring concrete for your slab, excavate between columns and install minimum R-10 rigid insulation at least two feet down and two feet out around entire perimeter. This will assist in mitigation of potential frost heaves. Under slab should have same insulation from wall-to-wall with a minimum 10mil vapor barrier on top of insulation and beneath concrete.
Walls – remove wall steel and place a well-sealed omni-directional WRB between framing and siding. Add 2×6 girts bookshelf style between columns flush to inside of posts. These girts will both provide an insulation cavity and will also serve as framing to support your interior liner steel panels. Then place R-30 Rockwool batt insulation between wall girts. This wall assembly will dry to building exterior. Moisture passing through your wall, should pass through WRB and may condense on inside of wall steel, leading to it either evaporating or running down inside of wall steel and out through bottom of siding.
At a 20′ span, roof trusses do not have to look very substantial in order to be strong enough to carry a decent amount of load. With specific information on how those trusses are built, we may be able to run them on our truss design software to determine if they would be adequate to support a ceiling load. We would typically have wanted to have raised heel trusses, so full depth of insulation can run from wall-to-wall.
Roof is going to pose some challenges, as there is no provision to prevent condensation from appearing on underside of steel roofing. If it were my own, I would have two inches of closed cell spray foam applied directly to underside of roof steel. Add gable and ridge vents. Then blow in R-60 fiberglass above a steel liner panel ceiling.
You may find it necessary to mechanically dehumidify – there is just no way to guarantee you will not have issues with excess humidity, given how you intend to use building.






DEAR POLE BARN GURU: What is practical priced good ceiling fan for a post frame 36 x 60 work shop, I plan on installing two. What height is good for a Modine hotdawg hanging natural gas heater with building with 14 ft walls? SCOTT in WISCONSIN RAPIDS
DEAR POLE BARN GURU: We have a pole barn it was purposely built to have an apartment upstairs; it originally was a stable below. It’s all living quarters now. We have had issues with the steel roof. We are switching to class 4 shingles. The building has no eaves as it has porches off both sides. We are working with a roofer. They are suggesting we use some ridged vent at the lower edge of the roof, by cutting a notch in the edge and installing it under the shingles and decking. That’s my understanding. Also, it will have a full ridge vent. The steel was applied on decking with tar paper under it. We have had leaking and condensation with it, as it is. Just wondering if you have any other ideas, or if the ridged vent at the lower edge of the roof will be a problem? It has 16″ deep trusses with blown in insulations above the sheet rock ceiling. Thanks for any input or ideas. JENNENE in RAPID CITY
DEAR JUSTIN: In most instances a reflective radiant barrier is a waste of your hard- earned dollars. They can be (when properly sealed) an excellent vapor barrier, however using a perforated product takes away even this as a possible benefit. Walls – from out to in…. Siding, Omnidirectional housewrap over bookshelf wall girts, fill entire cavity with Rockwool insulation batts, well-sealed clear poly vapor barrier, interior finish. Roof – Order raised heel trusses (at least an inch taller heel than depth of blown in fiberglass (not cellulose) insulation). Order roof steel with an Integral Condensation Control factory applied. Vent eaves and ridge in correct proportions. No ceiling vapor barrier.
DEAR POLE BARN GURU: I have an existing pole barn on property that I would like to insulate. I would like to steer away from spray foam but am worried as there is no Tyvek or vapor barrier on external side. What are my best options to void off any moisture issues and create a well insulated wall. JAMES in LAKE VILLAGE 

DEAR ROBERT: All of these recommendations are based upon meeting energy code requirements for conditioned buildings. Washington State will be a stickler for these.
DEAR POLE BARN GURU: What size posts should be used for 30′ x 40′ x 10 with 6/12 pitch in southern lower Michigan??? Storage/ garage / shop. STEVE in MARSHALL
“I read your blog often and I truly appreciate the wealth of knowledge you openly share. I am in the process of starting construction on a hybrid steel shop that will house a small apartment that the wife and I will move into once its finished. We will sell our current home and then build a smaller house adjacent to the shop. 50 X 80 with 24′ wide mezzanine on one end. My questions are centered around wall/roof construction as well as proper insulation. Roof: I plan to install a standing seam roof with ice/water shield over 5/8 plywood. As you are aware, with hybrid steel it is hard to ventilate the roof with this type of construction. This downfall didn’t outweigh some of the benefits so this is what I am stuck with. Would like to understand some insulation options. Note: I do have the building designed to handle the loading of a couple of cupula’s and have considered making these passive and active ventilation points. (Exhaust fans with some louvers that I have yet to get the details figured out on)Walls (2 options): (Note: I prefer not to plan or have to always be fully conditioning the shop to 72 degrees…..I plan to have that ability by mechanical means but I don’t want to consistently have to be conditioning that much space, therefore I think i prefer the building to be able to breath out to the perimeter. I realize this may be tricky between the roof type and wall type)Option 1: metal siding – would like some input on wall and insulation construction based on the above notes of conditioning. Option 2: Hardie board vertical board and batten walls. Same as above, would like your input. There will be components on the first floor and second floor that make up the apartment space. Our approach on insulation and wall construction may change within those enclosed spaces may vary as they will be conditioned separately from the open shop space. Hope you can help shed some light on this approach and again thank you for your time and knowledge. Thanks!”
Thank you for reaching out to us. I also qualify for those senior discounts and fully understand stair issues. When we built our own shouse (shop/house) in Northeast South Dakota 15 years ago we went with two stories and my lovely bride insisted upon having an elevator (we actually now have two of them).
DEAR POLE BARN GURU: When installing horizontal sheeting, does the top sheet always cover the bottom sheet when joined? GARY in EUFAULA
DEAR POLE BARN GURU: 
The structural system of a post-post frame home, its engineered plans and foundation are all going to prove to be less expensive than stick frame. Everything else is going to be pretty much the same – cabinets, fixtures and floor coverings do not suddenly become less expensive just because they were in a post frame building.
DISCLAIMER: This is NOT a Hansen Pole Building
Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays. With many questions to answer, please be patient to watch for yours to come up on a future Monday segment. If you want a quick answer, please be sure to answer with a “reply-able” email address.
TextraFINE® Post Frame insulation is made from inorganic silica sand which is formed into long textile-type glass fibers which are bonded together in random orientation by a stable thermosetting binder. This process produces unusually strong, resilient insulation which will return to full thickness following compression.
Foam board insulation is commonly placed against the steel building siding, between the girts of exterior walls. To prevent air infiltration, place rigid insulation boards tightly together and seal the seams with tape or caulk. This practice may worry some in cold climates since the foam board may act as a second vapor diffusion retarder. Studies have shown, condensation rarely occurs in these areas unless something else is seriously wrong with the wall assembly (like massive uncontrolled air leakage into the walls from the building). If the assembly is constructed correctly, the inside surface of the foam board stays warm enough to keep water vapor in its gaseous state long enough for it to escape.