Tag Archives: PEMB

Can No Longer Afford Spray Foam for a PEMB

Can no Longer Afford Spray Foam for a PEMB

Loyal reader CINDY in TYLER writes:

“I had a steel building (20×18)  built with steel frame and metal exterior. This is going to be my house. It will have a loft that is half the size of the building. Originally the builder talked me into spray foam and that’s what Ii planned to do. He said I had to use wood to frame inside the metal walls first, then run electrical and plumbing before the spray foam. That was a couple of years ago. Now that inflation has caused prices to soar, I am simply not able to afford the spray foam. My main concern is the condensation/moisture issue. i am doing the rest of the work by myself. Since I don’t have any help it’s not going to be feasible to remove wall panels to install house wrap or insulation. So I wanted to get your expert advice on how to handle this. Specifically I have a plan to run by you. So the idea is instead of building my framing inside the metal frame, move to the inside of the metal, attach wood frame to the inside edge of the metal frame. Insulate the inside of the wood frame and add a moisture barrier to the inside of the wood frame before drywall. I will lose 3.5″ of space all around the inside but i think that will take care of any moisture issues. Please tell me what you think about this plan and make any appropriate suggestions even if you don’t post this on your blog. Also I wanted to thank you for the wealth of knowledge you have readily available on your site. Can’t tell you how much help you have been.”

Mike the Pole Barn Guru responds:

Thank you for your kind words, they are greatly appreciated.

Normally (in your climate zone of 2A) I would be recommending closed cell spray foam as insulator of choice – due to a combination of heat and humidity. Your builder headed you in a correct direction.

Before we get into how to frame your interior, we need to address what is going to happen with your roof. With steel installed directly over framing (whether wood, or in your case steel), if there is no well-sealed thermal break, you are going to experience condensation issues. You are going to have to find a way to spring for two inches of closed cell spray foam sprayed directly to the underside of your roof steel. Steel frame and steel purlins should also be sprayed. If not, you are going to have condensation on them – steel is a wonderful conductor of heat and cold.

Now – on to your question at hand. For your walls, it appears most folks do exactly as you propose and build a 2×4 wood stud wall inside of their PEMB’s (pre-engineered metal building) steel wall girts. You will want to completely fill your wall cavity with insulation – I would recommend rock wool, as it is not affected by moisture (here is information on one particular product https://www.hansenpolebuildings.com/2013/03/roxul-insulation/). You want to make sure your interior vapor barrier is extremely well sealed, including outlets.

If you do not have a well-sealed vapor barrier under your slab on grade, please seal your concrete now. Your HVAC system should be designed to mechanically dehumidify, else condensation is going to haunt you forever.

Is Cor-a-vent a Right Product for Me?

Is Cor-a-vent a Right Product for Me?

Reader (and Hansen Pole Buildings’ D-I-Yer) LEE in IDAHO FALLS writes:

“Would this product https://www.cor-a-vent.com/purlin-vent.cfm be suitable for providing eave vents where no overhangs were designed. This product would be installed by recessing the eave strut (purlin) 1″ below the roof line and filling the gap with this product to provide air intake flow. Seems a better option than gable vents to get the best airflow.  It has a crush resistance of 7600# PSF.

Thanks”

 

For those who did not click on Lee’s link, here is some information from Cor-a-vent’s website:

Is your insulation a wet blanket? Chances are it is. You know the problems all too well—cold side condensation on your metal roof and siding. You probably can’t see it, but it could be robbing you blind. Even slight amounts of moisture in blanket insulation can seriously reduce its R-value. Don’t count on vapor barriers—every seam and penetration has to be sealed perfectly, and how often does that happen on the job? Moisture vapor penetrates just about everything, and once it’s trapped, you have problems. The heating bill goes up, insulation can sag and the roof fasteners and purlins will start to rust. What do you do? Next building, you specify Purlin Vent™, from Cor-A-Vent—“The Leader In Innovative Rooftop Ventilation” ®

Purlin Vent is the first real system solution for venting behind roofing and siding in metal buildings. Made from sheets of crush proof profile extruded PP* Purlin Vent serves as an excellent thermal break between the metal roof and the purlin when foam insulation is used. For blanket insulation, Purlin Vent with Insulation Shield does two things. One, it keeps the blanket insulation away from the underside of the roof. Two, it creates a passageway for moisture to diffuse harmlessly to the outside.  When used with any of Cor-A-Vent’s metal roof ridge vent applications, it creates a very effective system for removing moisture and keeping your insulation dry.”

Mike the Pole Barn Guru’s take:

While your best possible attic ventilation system would be air intake at eave and exhaust at ridge, this product is probably not your solution.

Post frame buildings work due to shear strength of properly fastened skin – in your case steel roofing and siding. In roofs, greatest shear loads are at eave and ridge – this is why you see diaphragm screws on each side of every high rib in these locations. Cor-a-vent is designed for use in PEMB (Pre-engineered Metal Buildings aka ‘Red Iron’) where rigid steel frames are carrying wind loads from roof to ground. PEMBs do not rely upon a stressed skin for their structural integrity.

If this product was to be used on top of your eave strut, screw shanks would be able to work back and forth under wind loads, in Cor-a-vents thickness. Over time you could expect to develop leaks at your eave line due to screw slotting and, under critical loads, it could be possible for this connection to become overloaded.

Gable vents are realistically your option given your building has no eave overhangs to place vented soffit in.

Choosing a Horse Riding Arena Structural System

Having a horse (or horses) in many parts of America means you will spend a great deal of time riding in inclement weather, or enjoying your horse tucked away safely in a stall. First one isn’t much fun for riders, second doesn’t get any riding done at all.

Reader (and new blog subscriber) DEBBIE in FERNDALE writes:

“Hello, I’ve just started receiving your blog and am enjoying it.  Would like to ask you a question about building a 70×150′ indoor riding arena which we plan to do this year.

It will be adjacent to our current outdoor arena, the space inside should accommodate two 20m circles and have enough at the short end to tie half a dozen horses.

We’d like two 14×14′ overhang doors centered in both short ends, allowing a hay trailer to drive thru during summer months when necessary.

The site is prepped with pit run.

Would appreciate your input on the benefits or cons of building a pole barn, steel, or solid sides with fabric roof.  Concerns include solid sides for wind shelter in the winter months when we will be using it, vs. ample light inside without too much provided electrical light – i.e. translucent upper side panels, light which fabric allows, etc.

Thank you for your thoughts!  Installation is upper NW Washington state.”

Mike the Pole Barn Guru writes:

Thank you for becoming a subscriber to my blog articles. My goal is to be both entertaining and informative – hopefully your expectations will continue to be met.

Our oldest daughter, Bailey, is a professional horse trainer in Tennessee, so I have a distinct advantage in receiving continued feedback from her when it comes to indoor riding arenas and stall barns. Your proposed 70′ x 150′ arena would be fairly close in proportion to what Bailey claims as perfect riding arena dimensions (https://www.hansenpolebuildings.com/2012/07/the-perfect-indoor-riding-arena/). She will also give you kudos for putting overhead doors on each end, rather than sliding doors – she wants to be able to ride up to a door, hit a remote, and open the door without having to get off her horse.

A fully engineer post frame (pole barn) arena allows you to utilize every foot of space, wall-to-wall. Natural lighting can easily be incorporated by using opaque white polycarbonate panels at one or both eave sidewall tops. While all steel (PEMB – pre-engineered metal buildings) are great for allowing wide clearspans, they have a downside when used for structures without concrete floors. Their structural steel frames require significantly sized concrete piers to be poured – at times requiring underground cables to be run from wall-to-wall in order to keep bases of steel frames from ‘kicking out’.  Of course the scope of the foundation will not be known until after you have acquired a PEMB and have to hire another Registered Professional Engineer to do a foundation design. Concrete piers and horse’s hooves do not mix well – I have seen steel arenas where interior wood kick walls had to be built several feet inside of steel frames, in order to protect hooves from piers. Fabric buildings are really not permanent structures, as fabric does deteriorate and eventually fail over time due to UV light.

Fabric buildings also have had a history of challenges supporting wind loads (https://www.hansenpolebuildings.com/2012/05/fabric-covered-building/) and snow loads (https://www.hansenpolebuildings.com/2012/05/fabric-buildings/).

Please reach out to me any time with questions – always glad to be of service in assisting people to get buildings they will love forever!

Twelve Reasons Why PEMB Are Great

Call them “red iron”, “bolt up” or Pre-Engineered Metal Buildings (PEMB) or a variety of other names and they are great buildings. Where they especially shine is where roofs clear span over 80 feet and where very low slope roofs are desirable (typically less than 3:12). And no, I did not hit my head and you did not wake up in a different space-time continuum.

Roughly 40% of commercial buildings are steel farmed. Annually roughly 3000 U.S. residential homes are built using all steel frames.

Here is a dozen reasons (in no particular order):

1. When working within defined standard dimensions high-tech engineering and design software simplify processes and make for efficient use of steel.

2. As long as foundation bolts are properly placed and bolt holes are correct, no field structural steel cutting, welding or drilling should be required.

3. Building components and steel sheeting can be shipped from regional manufacturing and warehousing locations to minimize freight charges.

4. Fully engineered buildings with third-party engineered foundation plans, simplify permitting processes.

5. Steel has a very high strength-to-weight ratio. Obviously footprint, height, roof slope and manufacturer will come into play, however an average weight per square foot for a PEMB shell seems to be roughly eight psf (pounds-per-square-foot).

6. Once foundations are excavated, formed and concrete is poured, a contractor with proper heavy lifting equipment can erect a fairly significantly sized building fairly quickly.

7. Fire resistant metal framing does not ignite. With addition of 5/8” Type X gypsum wallboard, steel furring and appropriate insulation options one and two-hour exterior wall fire ratings can be achieved.
8. Insects do not eat steel

9. With high-quality paint on a proper galvalume or galvanized substrate, steel roofing and siding require very little upkeep.

10. Fully engineered, properly constructed steel buildings withstand damage from earthquakes, winds, snows, hail and other weather extremes as well as an equivalent post frame building.

11. Dimensionally stable steel changes little with temperature – in a variance of 100 degrees a 50 foot width building expands or contracts just under ½ inch. Steel does not change dimension with shifting moisture content like wood framing does.

12. Clear span steel buildings promise endless floor plan possibilities, with no restrictive load-bearing walls required.

Stick Frame and Some Limitations

Stick Frame and Some Limitations


Perhaps stick built construction’s biggest advantage is builders and tradespeople are very comfortable working in and around stick framing. All registered architects and most building inspectors are very familiar with stick framing. The International Residential Code (IRC) provides a prescriptive ‘cook book’ to follow for adequate structural assembly, within certain limitations. These limitations include, but are not limited to, no story height of greater than 11 feet 7 inches (R301.3), no hurricane prone areas with a design wind speed of 130 mph or greater located south of Virginia, or 140 mph elsewhere (R301.2(5)B), and no ground snow loads over 70 psf (R301.2.3).

IRC802.10.2.1 further limits truss spans to a maximum of 36 feet and building lengths to 60 feet (measured perpendicular to truss span). Trussed roof slopes must be at least 3:12 and no greater than 12:12.

Wood is a very forgiving building material and, even when miscut, replacement material is usually only a short drive away. America’s home building industry has built traditional, wood stick framed homes, on site for decades.

Many builders, architects, carpenters and other subcontractors prefer to work on stick built homes as compared to alternative building systems.  Because traditionally framed houses are so popular, dimensional lumber and stick built framers are readily available.

Another advantage of stick built homes is they allow for a great level of design freedom.  You can design your barndominium with various ceiling heights, angles and curves, niches and other details. Stick framing one to achieve those unique details at a fairly affordable cost.

Despite its popularity, stick framing does have some drawbacks. Because stick built homes are assembled outside, over several weeks, framing lumber is subject to outside moisture.If lumber gets too wet, it can shrink and warp as it dries and cause cracks in the attached drywall.  This shrinking and warping can also make it difficult to properly insulate. To decrease  risks of potential moisture problems, ensure exteriors are covered with an appropriate and well-sealed Weather Resistant Barrier and lumber is properly dried before drywall and insulation are installed.

Another drawback of a stick built home is it usually takes several weeks to complete framing.  Total amount of time it will take will obviously depend on size and complexity of house plans and size, experience and availability of any particular framing crew.

A framing crew must precisely cut, assemble and erect barndominium framing components sometimes in adverse weather conditions.  Working around adverse weather conditions is another challenge with stick framing.

Although site-built, stick framed homes clearly dominate America’s housing market, there are several other ways to build a barndominium’s structure. These include post frame, PEMB (pre-engineered metal buildings), weld up steel and concrete.