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Vapor Barriers, Post Longevity, and Spray Foam

This Wednesday the Pole Barn Guru answers reader questions about the need for a vapor barrier, the longevity of properly treated posts, and the better spray foam between open and closed cell.

DEAR POLE BARN GURU: Hello Sir, hoping you can help answer a question I cannot get a straight answer on. Currently building a 30x40x14 building and have the walls and roof house wrapped with Kelly Clark Block It. Steel is going on the building now. I just ordered steel for interior ceiling and trying to figure out if I should add a vapor barrier to bottom of truss first. Thoughts? MATT in ILLINOIS

DEAR MATT: Block it is wrong product for under roof steel. It allows moisture to pass through and be trapped between it and roof steel. As long as you do not blow in cellulose, you should not need a ceiling vapor barrier.

DEAR POLE BARN GURU: I bought a pole barn that has been retrofitted to a house. The posts are in ground. I’m worried about future resell and longevity of the post. Also, I’m in a cold climate and wonder if a proper footing would help with heating. Is there any good way to retrofit from in ground post to stem wall or something similar. I’m sure it’s all possible if money was not an issue. I’m looking for an economical solution. Thanks!! NICK in WEST LIBERTY

DEAR NICK: Properly pressure preservative treated columns (UC-4B) should outlast anyone alive on our planet today, especially in climates (such as yours) not prone to termite infestations. As for improving ability to heat – dig a trench around outside of building at least two feet wide and two feet deep. Invest in 2′ x 8′ (or 4′ x 8′ to be cut in half lengthwise), R-10 EPS insulation boards. Attach vertically to exterior side of pressure treated splash plank with top of insulation even with top of interior concrete slab. Run another 2′ horizontally out away from building at bottom of vertical. Any portion of vertical insulation above backfill will need to be protected from UV rays. This should keep your slab from getting so cold, as well as help to avoid frost heave. If you are in an area prone to burrowing rodents, you should further protect insulation https://www.hansenpolebuildings.com/2021/03/rascally-rodents/

DEAR POLE BARN GURU: I am trying to decide whether to go with open cell or closed cell spray foam on my bare metal pole barn walls. I will be enclosing the walls with some material, most likely plywood. What are your opinions regarding the pros/cons (is one or the other worse for corrosion, condensation, other pertinent factors, etc.) of the two foam approaches? Thanks so much! TERRI in CHESTER

DEAR TERRI: Open cell spray foam allows moisture to pass through and condense against steel cladding. I would not recommend it being used unless a two-inch thick layer of closed cell was first applied, then add open cell for extra R value (and to deaden sound).

This entry was posted in Building Interior, Lumber, Columns, Insulation, Pole Barn Homes, Pole Barn Questions, Pole Barn Design, Roofing Materials, Pole Barn Planning, Barndominium, Ventilation and tagged steel roof moisture barrier, moisture barrier, UC-4B, open cell spray foam insulation, closed cell spray foam insulation, vapor barrier, spray foam, UC-4B pressurem Preservative Treated columns on April 3, 2024 by admin.

Sliding Doors, Roofing Tar on Posts? and Condenstop!

Sliding Doors, Roofing Tar on Posts? and Condenstop!

DEAR POLE BARN GURU: I have an arena with 12×12 openings at each end. I want to find a rolling door solution. I would like to have 6.5” doors that open left and right. I’m also interested in finding a door solution that instead of tan metal (matching my building) I find translucent panels.

I can upload photos in a few days when I return to the farm.

Is this something you can help with?

Thanks JASON in CENTRAL POINT

DEAR JASON: If yours is typical post frame (pole) building construction, your opening probably measures 12 feet from center of column to center of column, in which case you would be looking at needing a 12 foot width split sliding door. This would give you two door leafs just over six feet in width, enough to cover the opening, provide an overlap on each side and be able to be covered with two three foot widths of steel siding.

You should be looking at a door system which has all steel girts (horizontals) and verticals, preferably pre-painted. While translucent (polycarbonate) panels could be used, I would typically not recommend them due to their not having a resistance to wracking.

In our case, Hansen Pole Buildings only provides sliding door components with the investment into a complete engineered post frame building kit package. We typically would recommend you pay a visit to the ProDesk at your local The Home Depot to acquire the parts you will need.

DEAR POLE BARN GURU: Enjoy reading your blog. I will be building in thick wet clay and am worried about post rot due to the amount of moisture. Will painting the entirety of the buried portion of treated pole in roofing tar help preserve the wood? TIM in LEXINGTON

DEAR TIM: Thank you for your kind words, I hope to be both entertaining and informative. Will painting the entirety of the buried portion of a treated pole in roofing tar help preserve the wood? Well, it might, although I have found no studies which would confirm the ability. I did find an interesting article in Scientific American, which may shoot down the idea: https://www.scientificamerican.com/article/coal-tar-and-its-products-as-preser/.

The reality of the situation is, a properly pressure preservative treated column is going to outlast all of us, and probably our grandchildren. This article should be of interest: https://www.hansenpolebuildings.com/2017/12/will-poles-rot-off/.

DEAR POLE BARN GURU: Hello guru. I bought a bunch of 1/2x4x8 sheets of insulation to put on my new 40×60 barn roof under the steel and on top of purlins .Planned on taping all seams for a moisture barrier. It’s not the really dense foam more of a bead style with a silver back on one side plastic on the other so it’s a little bit squishy. After thinking about it what worries me is that after time it may cause the barn screws seal to loosen up. If the foam lowers it could cause the steel to drop a bit. Than could create a leak under the rubber washer. Or do you think it will work ok? Should I just use Tyvek instead on the purlins? What is your opinion Guru? ABE in WAYLAND

DEAR ABE: Do not use this insulation as you have intended, it will cause you nothing but grief. Not only will your post frame barn roof leak, but the diaphragm strength of your roof steel will be severely compromised, which could lead to a catastrophic failure. Tyvek and other building wraps are not condensation control barriers, they are moisture barriers. There are several possibilities – invest in roof steel with Condenstop or Dripstop preapplied, use a radiant reflective barrier between the purlins and roofing, or spray closed cell foam on after the roof is installed.

This entry was posted in Roofing Materials, Steel Roofing & Siding, Sliding Doors and tagged post rot, sliding doors, pressure treated columns, steel roof moisture barrier, double sliding doors, Condenstop on March 12, 2018 by admin.

Drip Stop

When the temperature and humidity conditions reach the dew point, moisture can condense on the underside of steel roofing. This condensation has the potential to cause water damage and other problems inside of pole buildings.

Some of the Hansen Pole Buildings steel suppliers are now offering an internationally patented CCM (Condensation Control Membrane) which can be pre-applied to their steel panels. This innovative product works by creating a medium for trapping moisture in the specially designed pockets formed within the felt’s membrane. Holding moisture until conditions go back below the dew point, Drip Stop is then able to release the moisture back into the air in the form of normal humidity.

Drip Stop is durable – it isn’t susceptible to ripping, tearing or deterioration like many common metal building insulation and vapor barrier products. It is easily cleaned with a hose or pressure washer. It may result in time savings – as no other product needs to be installed between the roof purlins and roof steel. It is approved for use in animal confinement buildings. Drip Stop is UL 723 approved for flame spread and smoke generation and comes with a 20 year adhesion warranty. It also reduces exterior noise.

The skids of steel with Drip Stop applied must be stored prior to use, to prevent moisture from becoming trapped between panels, which may cause staining as well as damage to the panels. This moisture can originate from a variety of sources, such as rain, high humidity or condensation. Panels should be stored in a dry location and installed as quickly as possible after delivery. If this is not possible, panels should be separated from one another to allow for air circulation to prevent panel damage.

The steel panels do require some extra preparation work, prior to installation. Panels are to be first laid with the Drip Stop material facing up. Using a heat gun, the exposed end lap or eave portion needs to be heated to fuse the Drip Stop fibers. Care must be given to avoid overheating any one spot, which could potentially damage the panel’s finish on the exterior side. The Drip Stop material should neither be completely melted, nor fused beyond the lap or overhang area of the panel. Allow panels to cool, prior to installation. Failure to properly prepare panels may result in the Drip Stop material attracting water from outside the building, resulting in possible leaks, mold and/or mildew.

If anyone has personal experience using this product, feel free to respond and let me know what the pluses and minuses were in using Drip Stop. It sounds like a great product, and may be a step in the right direction for a better moisture barrier than what has been currently available. However, at first glance the application sounds too complicated and somewhat risky for anyone other than someone who has lots of practice installing it. Let me know what you think folks, I am always looking “for a better mousetrap”!

This entry was posted in Roofing Materials, Steel Roofing & Siding and tagged roof insulation, drip stop condensation control, steel roof moisture barrier on November 13, 2012 by admin.