Home >> monolithic slab

Tag Archives: monolithic slab

A Radiant Barrier Issue, Venting in Humidity, and Frost Walls

This week the Pole Barn Guru answers reader questions about insulating a building that already has reflective foil radian barrier, if one needs vents or exhaust fan in the gable ends of the roof with the high heat/humidity of Alabama, and requirements for frost wall or slab for frost heave.

DEAR POLE BARN GURU: I recently moved into a house with a 40×30 pole barn (wood post and wood trusses) with a metal exterior. The building has a reflective foil radiant barrier between the metal and wood structure. It is extremely hot in the summer and cold in the winter. I want to insulate and cannot afford spray foam. I also don’t have the ability to remove the walls to remove the foil barrier that way. I do have some Silvercote insulation that has an attached vapor barrier. It is just a fiberglass roll insulation that has an attached vapor barrier to it. It is sold around here for use as insulation in metal buildings. I was given enough to insulate the whole shop from someone that had left overs. I would like to install this insulation to help with temps in the shop. I have tried to research to get an answer on the best way to go about this. The shop builder said just put it up but I feel that would create a double vapor barrier. Is my best route to cut the foil radiant barrier out and then install the fiberglass insulation with vapor barrier facing the interior of the building? This would basically take the foil barrier out and install the fiberglass against the metal with the attached face vapor barrier to the inside of the building. I want to make sure I do it right. Thank you. DAVID in OKLAHOMA CITY

DEAR DAVID: If you are dead set on using this Silvercote insulation then you should cut out any foil radiant barrier. You never want to have a double vapor barrier situation as any trapped moisture will have no method of escaping. Downside of this is you do not have a Weather Resistant Barrier (aka housewrap) between framing and siding. An option to consider would be to resell your metal building insulation, then use unfaced Rockwool batt insulation, as it is unaffected by moisture.

DEAR POLE BARN GURU: I plan to build a 28×48 metal pole barn, concrete floor, 12′ eave with 8/12 pitch. Barn will have 6 3×4 windows, and two 10×10 roll doors, one roll door on each gable end. For now, the roof will be insulated with 3in closed cell foam. I plan to insulate the walls down the road with rigid foam board. The building will not have A/C. Question: Do I need vents or exhaust fan in the gable ends of the roof with the high heat/humidity of Alabama? There will be no ridge vent or soffit vents. I may not have the building open every day, either. Thank you. JASON in MONTGOMERY

DEAR JASON: While placing permanent vents might alleviate your possible mold/mildew/condensation issues, they will defeat your insulation investment. In reality, you should look to a qualified local HVAC provider to provide mechanical dehumidification, else you will have regrets forever. Make sure to have a vapor barrier under your concrete floor, to help reduce interior moisture gain.

DEAR POLE BARN GURU: FROST HEAVE, 44′ deep by 64 long pole barn 20 ceiling height, Tenant build, will be insulated but NO HVAC initially. However, is some type of concrete frost wall (downturn?) via monolithic slab required? Dimensions? MIKE in CINCINNATI

DEAR MIKE: Your slab on grade can be poured to a consistent thickness throughout and all you need to do is properly insulate your slab edge to meet IECC (International Energy Conservation Code) requirements.

This entry was posted in Pole Barn Questions, Pole Barn Planning, Pole Barn Heating, Barndominium, Building Interior, Budget, Pole Barn Homes, Insulation and tagged humidity, insulation, reflective radiant barrier, frost heave, Ventilation, rock wool, monolithic slab, exhaust fans, gable vents, frost wall, moisture barrier on July 9, 2025 by Rick Ochs.

Monolithic Slab, Column Spacing and Girt Sizes, and Building Costs

This Wednesday the Pole Barn Guru answers reader questions about pouring a monolithic slab in Iowa, a question about columns spacing and girts sizing, and what the costs to build a garage with living quarters above might be.

DEAR POLE BARN GURU: I’m building a barndominium in Iowa and I wonder if I can do a monolithic slab in a freezing area where the typical frost footing is 42″? Thank you. DAVID in KALONA

DEAR DAVID: Yes you can, by attaching rigid insulation boards vertically to inside of pressure preservative treated splash plank, with top of insulation at top of slab. Extend insulation boards down 42 inches, or down and then out to follow Frost-Protected Shallow Foundation requirements. Read more about Frost-Protected Shallow Foundations here: https://www.hansenpolebuildings.com/2016/11/frost-protected-shallow-foundations/

DEAR POLE BARN GURU: I’m looking at a pole barn design that I’d like to do, but I’m considering 10′ OC or 9′ OC post spacing rather than 8′ I’ve run the numbers for the roof and the posts, but I wanted to know if the wall girts could handle that span? Looking at 2×6 girts, any advice on how to make sure they stayed within reasonable deflection limits? Also this pole barn has interior walls, as it’s a “barndominium” so we’re looking at doing residential grade, pulling permits etc. on this project. ALAN in ST. GEORGE

DEAR ALAN: We actually provide enclosed buildings with columns as distant as every 16 foot on center. Our 3000f glulaminated columns allow us to minimize worst part of post frame construction – having to dig holes. By use of bookshelf wall girts, we can engineer to handle wind loads of 140 miles per hour or greater and wind Exposure C (far greater than most locations will ever require). We provide a plethora of residential post frame buildings every year, so are well versed with IRC structural requirements. Read more about bookshelf girts here: https://www.hansenpolebuildings.com/2011/09/commercial-girts-what-are-they/

DEAR POLE BARN GURU: How much does it cost to get a pole barn one car garage with living quarters above fully finished out on my own property. JENNIFER in GRANDVIEW

DEAR JENNIFER: Fully engineered post frame, modest tastes, DIY, budget roughly $75-85 per square foot for conditioned spaces, $35 for all others. Does not include land, site prep, utilities, permits.

This entry was posted in Pole Barn Homes, Pole Barn Design, Pole Building How To Guides, Barndominium, Pole Barn Planning, Shouse, Shouse, Building Interior, floorplans, Budget, Columns, Lofts, Pole Barn Questions and tagged DIY, frost depth, bookshelf girts, monolithic slab, girt sizes, girts spacing, garage with living quarters, column spacing on January 29, 2025 by Rick Ochs.

Rafter Size, Lean-to on Slab, and “Barndominium?”

This Wednesday the Pole Barn Guru tackles questions regarding rafter size for a lean-to addition, adding a Lean-to to an existing building on a monolithic slab, and “the difference between a pole barn home and a barndominium?”

DEAR POLE BARN GURU: I am building a lean-to on an existing pole barn. It is 32′ long and it will be 14′ wide on a 3/12 pitch The posts are 8 ft on center. My question is what size rafter do I need to span 14′ at 8′ on center with 2×4 purlins on edge? Thanks. MICHAEL in LIZTON

DEAR MICHAEL: A caution – if your shed roof ties in at any height other than exactly at eave, or is not at same slope as existing roof, you have a snow slide off/drift load to contend with and are best to engage an engineer to account for this extra loading. An exception would be if you have a snow retention system on your existing roof. Assuming above is not an issue, please read on. As I do not know your loads, you can fill in blanks in this formula to find out: (roof live load + roof dead load) x spacing (in your instance 96″) x span in feet squared (14′ squared for you). Divide this answer by: 8 x Rafter Section Modulus x Fb (fiberstress in bending of lumber proposed to be used) x 1.15 (duration of load for snow) If your result is 1.0 or less, then you are golden. Section Modulus is depth of member squared x width of member divided by 6 Example : 2×12 = 11.25″^2 x 1.5″ / 6 = 31.64 Fb for #2 grade Southern Pine will be 2×8 = 925; 2×10 = 800; 2×12 = 750

DEAR POLE BARN GURU: Can I build a pole lean-to and attach it to my shop that is built on a monolithic slab? I did not intent to put a concrete floor in the lean-to. Can I do this without pouring a foundation for the lean-to? The Lean-To will be 50′ by 16′ with metal sides and roof. Thank you. GLEN in HYSHAM

DEAR GLEN: Maybe, provided your existing building footings are adequate to support weight you will be adding. Easiest and safest way is to set a row of columns directly alongside existing building wall, so you can treat new structure as being self-supporting. You will not have to pour a foundation, you can auger holes, place UC-4B pressure treated columns in holes, then backfill bottom 16-18″ with premix concrete to create a bottom collar. If your new lean-to has a pitch break, or is lower than main roof on high side, you do need to account for weight of slide off/drifting snow onto it. This can be avoided, by installing a snow retention system on your existing roof.

DEAR POLE BARN GURU: What is the difference between a pole barn home and a barndominium? SHARON in WESTCLIFFE

DEAR SHARON: Barndominium is pretty much a made-up term, with no recognized or official description. For sake of discussion, any pole barn (technically post frame) home would be a barndominium, while barndominiums could also be other structural systems with a ‘barn like’ look and most often steel roofing and siding.

This entry was posted in Pole Barn Homes, Pole Barn Questions, Pole Barn Design, Building Styles and Designs, Constructing a Pole Building, Barndominium, Pole Barn Planning, Concrete, Footings, Columns and tagged barndominium, lean-to, Post Frame Home, slab, Pole barn home, monolithic slab, Rafter, rafter size on November 8, 2023 by admin.

New Build Features, Concrete Costs, and a Monolithic Slab

This week the Pole Barn Guru answers reader questions about specific features for a new build, possible costs for concrete for a 60x150x12 red iron building, and installing a monolithic slab in an area with rocky soils.

DEAR POLE BARN GURU: I like a 35′ wide by 45′ deep 18′ high. Ridge running the depth of the barn. I’d like 20′ lean-to’s on each side. 2 14’x14′ doors, one in front and one in back. Want to drive through. I’d like to know if we can have an open floor plan? I’d like all the inside walls to open into the lean-to’s. I was also wondering if we can use roofing panels that allow light through on 1/3 of left lean-to? That area would be used for plants. Let me know if it can be done and we can add some more details to get it done. Thanks. SHANE in BRIDGETON

DEAR SHANE: Provided you have available space, you might want to consider a 36′ x 48′ main building, as it is more efficient in materials usage and will likely be roughly same in investment. Yes, you can have an open floor plan, with no inside walls between main building and lean-to areas. While it is possible to use opaque white translucent polycarbonate panels for portions of roofs, they can prove to be problematic. From a structural aspect, polycarbonate will not adequately transfer wind shear loads, so those area will require steel strapping between roof purlins and sheathing. Below this area, everything will seriously bake – including supporting lumber. All of this lumber (below polycarbonate roofed areas) should be pressure preservative treated to reduce potential incidence of decay.

DEAR POLE BARN GURU:
Can you estimate concrete cost for a 60x150x12 building? Red iron.
WALTER in FORT WALTON BEACH

DEAR WALTER: For a red iron building, I would need to see engineer designed foundation plans in order to estimate required concrete for foundation, it will take a significantly greater amount of concrete than would a fully engineered post frame building. For a similar size post frame building, expect to use roughly 11 yards of concrete for footings and bottom collars for columns – this is based upon a 2000 psf (pounds per square foot) soil bearing capacity, Vult (Ultimate design wind speed) of 150 mph (miles per hour) and a Wind Exposure C. https://www.hansenpolebuildings.com/2022/06/wind-exposure-and-confusion-part-iii/

DEAR POLE BARN GURU: I am working with Jackson on a quote for a 40x60x16 pole barn. The plan was to install the barn on a monolithic slab as our soil up here in Rhode Island is rather rocky. My town building inspector informed me that I would need to submit an engineering/stamped plan for my concrete work. Jackson suggested I reach out to you to discuss if there are any alternatives to a monolithic slab and what your recommendations would be. ALEX in WEST GREENWICH

DEAR ALEX: If a monolithic slab on grade ends up being your best alternative, we can provide engineer seals for it within our drawings. Anticipate having to dig a trench 24″ deep around perimeter and having to insulate slab edge.

There are alternatives – least invasive and most affordable will be to excavate square piers at column locations, slab itself will pour on grade.

Either of these would require wet set brackets (included in quote Jackson provided) and insulation requirements would depend upon if building will be heated or not, as well as if radiant heat will be used in slab.

This entry was posted in Pole Building How To Guides, Pole Barn Planning, Pole Barn Structure, Concrete, Footings, Professional Engineer, Skylights, Roofing Materials, Barndominium, Constructing a Pole Building and tagged monolithic slab, new build, rocky soils, post frame quote, concrete costs on May 31, 2023 by admin.

Fun With a Cheap Steel Truss Pole Building

Most of our country is unfamiliar with low budget steel truss pole barns produced and sold primarily in Southeastern states. There is a reason these are prevalent where there is no snow – just in case you were wondering.

Disclaimer, I have no issues at all with prefabricated light gauge steel trusses, provided they have been manufactured to engineer sealed drawings, specific to loading conditions where they will be put into use. AND if they are fabricated by a certified welder (rarely occurs).

Reader KEVIN in COLUMBIA writes:

“Hi Guru,

I recently purchased a home and the property included a 32×84 Pole barn. The barn was never dried in and was barely completed by the previous owner. However, everything is solid, square and plum; with the exception of a few pieces of steel on the roof that were never installed, it is a solid structure. Immediately after purchasing the home I had a monolithic slab poured under half of the structure that will become the foundation for the home of my new shop. I am quite comfortable with carpentry, but not so much with insulation. How do I go about condensation proofing the roof? I really do not want to pull the existing roof panels off to lay a vapor barrier over the purlins. My intention is to have a well ventilated attic, insulate the walls, and blow in insulation over the ceiling. I have heard of some people installing foam board to the exposed steel. Spray foam is an option, but one that is out of my price range for the moment. I have attached some images for your inspection. The 3D CAD models should provide a better illustration of what is under the roof. I look forward to your response.”

Kevin is now experiencing joys associated with buildings sold ‘on the cheap’ – with barely enough materials to get a roof on with a minimal budget. It would have been so simple for this building to have been originally sold and erected with provisions to control roof condensation. Either a Reflective Radiant Barrier (RRB) or an Integral Condensation Control (ICC) would have easily avoided your current situation.

This style of building does not lend itself well to installation of a ceiling (there are no clips along truss bottom chords to accept ceiling joists). My educated guess is these trusses are not designed to support weight of a ceiling. With 2×6 purlins spanning 12 feet, they are sadly not stiff enough to keep drywall joints from cracking – so you are going to be faced with lots of limitations.

Foam board might be a solution, however you would need to have each panel 100% air sealed between purlins in order to do so. Chances of success range close to zero. You are left with two choices – remove roof steel, install a RRB and reinstall roofing or two inches of closed cell spray foam (roughly $5700). Hopefully you have poured your slab on grade over a well-sealed vapor barrier, if not – use a sealant on top of it (not as effective, but better than nothing).