Tag Archives: radiant reflective barrier

Insulation, Snow Loads, and Best Choice for Condensation

The PBG answers questions about insulation, snow loads, and best choice for condensation.

DEAR POLE BARN GURU: I am wanting to finish the interior of my pole barn and have an cathedral like ceiling. If I were to follow the trusses up to the peak with foam board Insulation and use 2x4s spanning between the trusses for support would there be enough air flo between 2x4s and metel to prevent condensation? If not is there a way. I have a ridge vent along peak and soffit vents on both sides of 1ft eves. Thanks for taking the time to answer. TIM in PORTAGE

DEAR TIM: To begin with, I will surmise you have either a rather typical Midwest style post frame (pole barn) building with trusses spaced every four feet on top of “truss carriers” (headers) or a building with single trusses widely spaced somewhere from seven to 10 feet on center.

foam insulation installation

You have a couple of choices – if you are going to utilize the existing intake (soffit vents) and exhaust (ridge vents) then a minimum of one inch of clear airflow must exist above the insulation. The high ribs of the roof steel will not provide adequate ventilation and there is really no way to create it after the fact. An alternative would be to seal the vents and use closed cell spray foam on the underside of the roof system. The closed cell foam should take care of any condensation concerns from the underside of the roof steel and it provides approximately an R 7 insulation value per every inch of thickness.

 

DEAR POLE BARN GURU: Can your building be designed to handle a 40# snow load? 24 x 30. JIM in WISCONSIN RAPIDS

DEAR JIM: Any snow load is very possible to be designed for, even those at high altitude snow ski resorts (including this one: https://www.hansenpolebuildings.com/2014/04/2014-winter-olympics/). Besides the snow loads in excess of 200 pounds per square foot at ski resorts, I’ve also provided post frame buildings in places like Glacier National Park, where the snow is so deep the park roads close for months in the winter.

 

DEAR POLE BARN GURU: I am planning on a 24x48x12 steel truss pole barn for vehicle/toy storage. Would you recommend a radiant bubble material under the metal to keep the inside of the barn for becoming a convection oven sitting in the hot Florida sun? Best wishes, JOHN in FLORIDA

DEAR JOHN: My first choice would be closed cell spray foam. While it is going to be more expensive, you will save greatly in labor as opposed to using a radiant reflective barrier. Radiant Reflective Barrier, installed correctly, might give you the performance you are seeking. If you do go with the barrier, single cell will perform pretty much as well as single cell. Buy six foot wide rolls with a tab. The tabs should have a pull strip over adhesive, which eliminates the need for taping seams. The six foot wide rolls mean fewer pieces to handle and overlaps to seal.

 

 

 

3M VHB Tape

3M™ VHB™ Tape

Reader WILLIAM in DYER writes:

“I’ve been researching pole buildings, and the weak point for putting one up seems to be the screws and washers.  Have you looked into using 3M™ VHB™ tape instead of screws and fasteners for attaching the metal exterior sheeting? What are the pros/cons of tape only? Thanks.”

Personally the only way the screws holding the steel roofing and siding on would be the weak point would be if the wrong product is being used, or the right product is being improperly installed.

Here is the scoop on VHB™ tape straight from 3M™:

Details

  • Fast and easy-to-use permanent bonding method provides high strength and long-term durability
  • Virtually invisible fastening keeps surfaces smooth
  • Can replace mechanical fasteners (rivets, welding, screws) or liquid adhesives
  • Black, 0.045 in (1.1 mm), modified acrylic adhesive and very conformable acrylic foam core bonds to a wide variety of substrates including powder coated paints and irregular surfaces
  • Eliminate drilling, grinding, refinishing, screwing, welding and clean-up
  • Creates a permanent seal against water, moisture and more by offering better gap filling capabilities
  • Pressure sensitive adhesive bonds on contact to provide immediate handling strength
  • Allows the use of thinner, lighter weight and dissimilar materials

 

Dream, Design, Deliver with our 3M™ VHB™ Tape 5952. It is a black, 0.045 in (1.1 mm) modified acrylic adhesive with a very conformable, foam core. It can replace rivets, welds and screws. The fast and easy to use permanent bonding method provides high strength and long-term durability. It offers design flexibility with its viscoelasticity and powerful ability to bond to a variety of surfaces.

Convenience Meets Extreme Bonding Power 
Our 3M™ VHB™ Tape consists of a durable acrylic adhesive with viscoelastic properties. This provides an extraordinarily strong double sided foam tape that adheres to a broad range of substrates, including aluminum, stainless steel, galvanized steel, composites, plastics, acrylic, polycarbonate, ABS and painted or sealed wood and concrete. Our bonding tapes provide excellent shear strength, conformability, surface adhesion and temperature resistance. They are commonly used in applications across a variety of markets including transportation, appliance, electronics, construction, sign and display and general industrial. Reliably bonds a variety of materials with strength and speed for permanent applications. 

Dream, Design, Deliver with the 5952 Family of 3M™ VHB™ Tapes 
The 5952 family of 3M™ VHB™ Tapes utilizes modified acrylic adhesive on both sides of a very conformable, adhesive foam core. The combination of strength, conformability and adhesion makes this family one of the most capable and well-rounded 3M™ VHB™ Tapes. It is specifically designed for good adhesion to high, medium and lower surface energy plastics and paints, metals and glass. Applications for this tape include bonding and sealing polycarbonate lens over LCD, signage and windows to post-painted control panels. 

An Unconventional Foam Tape 
We invented 3M™ VHB™ Tapes in 1980 as the first of their kind. These unique tapes combine conformability with a strong, permanent bond. The result is a family of extraordinarily strong tapes that adhere to a broad range of substrates. 3M™ VHB™ Tape is a proven alternative to screws, rivets, welds and other forms of mechanical fasteners. Skyscrapers, cell phones, electronic highway signs, refrigerators, architectural windows and more all rely on this specialty bonding tape for one or more steps in the assembly, mounting, fastening and sealing process. This trusted and reliable tape offers a consistent bond, outstanding durability and excellent solvent and moisture resistance. 3M stands by all of its products and is there to provide you with design guidance and technical support when you need it. 

Proven Reliability from 3M™ VHB™ Tapes 
3M™ VHB™ Tape offers a durable bond in a way that mechanical fasteners can’t. This tape enhances the appearance of finished goods by eliminating rivets and screws while providing immediate handling strength. In most cases, fastening with 3M™ VHB™ Tape is a quicker process than drilling, fastening, or using liquid adhesive. Our versatile line of tapes can be used indoors or outdoors in a variety of applications, including window, door and sign assembly, electronics, construction and countless other industrial applications. Chemically resistant as well as UV and temperature stable, 3M™ VHB™ Tape can withstand the heat of Dubai to the cold of Canada. The unique acrylic chemistry is extremely durable and resistant to change over time, making this a long-lasting and powerful tape you can trust. 

Bringing Better Ideas to the Surface through Science and Innovation 
In our 3M Industrial Adhesives and Tapes Division, we apply the science of adhesion to deliver innovative solutions that improve the design and manufacturing processes of companies around the world. In the end, our technologies help customers like you deliver competitive products to the market faster and more efficiently. 

Mike the Pole Barn Guru comments:

Why it might not be the best choice….

OLYMPUS DIGITAL CAMERA

In order to utilize it with the steel panels, it would need to be tested for shear strength by an independent engineer. It would preclude the use of Building Wrap (like Tyvek) in walls, as well as radiant reflective barriers or Dripstop/Condenstop in roofs.

While it sounds like an excellent product, the cost along may prove prohibitive, as the lowest price I am seeing is somewhere around 70 cents per lineal foot, making it around 10 times as expensive as the diaphragm screws we provide and even more expensive than the smaller diameter lesser quality fasteners used by most post frame suppliers and builders.


 

Condensation Under Roof Steel

Condensation Even With Radiant Barrier Installed Under Roof Steel

It seems every winter I get a few messages similar to this, So far, this winter, I have gotten two, both from newly constructed post frame buildings and from the same area of the United States (which is known for high humidity).

Reader SAM in GREENBANK writes:

“Hi there.  I’ve almost completed the building, and It’s been getting cold lately.  I noticed that every time we have a frost I have condensation drips all over inside the barn.  I was under the impression that the foil backed bubble wrap was supposed to prevent this.  Is there something I can do to stop it?   Is this normal?   I’m having to keep all my tools under cover even though they are inside.  Not ideal.”

Mike the Pole Barn Guru Responds:

The radiant reflective barrier does keep warmer moist air from contacting the underside of the colder roof steel and condensing. If it has been below freezing inside your building, and fairly humid, water vapor will freeze to the underside of the barrier as well as the roof framing members. Most often the excess humidity is a product of a relatively freshly poured concrete floor (tremendous amounts of water vapor are expelled from a concrete slab as it cures), a concrete floor which does not have a well sealed vapor barrier beneath it, or (in buildings without a concrete floor) the ground under your building will not freeze and when the ground outside starts to freeze the excess ground moisture rises inside of the building (think of a cork being removed from a bottle).

Possible solutions (may have to be used in combination): heat the building to just above freezing, open the doors to allow excess moisture to escape (especially in cases with a fairly fresh pour or no slab), if no vapor barrier under a slab – seal the surface of the slab to prevent moisture from coming through. Basically it takes a reduction of humidity inside of your building.

In cases where eave and ridge ventilation was not provided for initially, adding gable vents might help to alleviate some of the interior humidity. When I was a builder, we erected a boat storage building over (we found out later) what had been a pit where asphalt waste from old roads had been deposited. Water sat in between the chunks of asphalt – we had basically built over an underground lake!

The only solution was for the owner to install power vents to pull the humidity out of the structure!