Tag Archives: adding insulation to a pole barn

Insulating a Room in an Unheated Pole Barn

Insulating a Room in an Unheated Pole Barn

Regular readers of this column recognize insulation as being a hot (pun intended) topic of discussion – not just entire buildings, but also of a room or rooms in an unheated pole barn.

Reader RICHARD in WOODSTOCK writes:

“I have a 50 x 75 pole barn with 15 foot side walls. The building is 8 years old and is unheated; I did insulate the roof during construction to prevent the traditional roof condensation which has worked well. Currently, I am in the process of building a 22 x 26 shop in one corner of the barn which will be heated and cooled.

Insulating WallsOn the two outside walls of the shop I placed 1 ½ inch foam board between each of the barn wall girts then built 2×6 stud walls in between the pole legs. I then placed built two remaining free standing 2×6 walls to complete the shop walls. I placed faced R19 insulation in all the stud walls and finished them off with ACX plywood on the inside of the shop and CDX on the outside (free standing) shop walls. I then placed 22 foot long TGI’s as ceiling joists so I can have storage above the shop which I then placed ¾ inch tongue and groove plywood on top. I am now at the point to insulate the ceiling and finishing it off with a suspended ceiling with a gypsum type ceiling tile. I plan on placing R30 unfaced insulation in each of the shop ceiling bays but don’t know if I should use a poly type barrier before putting up the suspended ceiling.

I am concerned about moisture in the shop ceiling and issues that would cause.

Any advice you may have would be greatly appreciated.”

Mike the Pole Barn Guru responds:

Normally ceilings do not have a vapor barrier because you want to have warm moist air rise and escape into the vented attic space. In your instance, you are creating a cavity which could very well collect moisture as the 3/4 inch T & G plywood is going to pretty much prevent moisture from escaping. If you use a vapor barrier on the underside of the TGIs, you have now trapped the moisture inside of the shop you have created. My instincts tell me to use the vapor barrier and be prepared to have some sort of exhaust fan to remove excess moisture in the room, or to have a dehumidifier. You can minimize the moisture in the room by using a good sealant on the top of the concrete slab. You might also look at using a product such as Roxul (https://www.hansenpolebuildings.com/2013/03/roxul-insulation/) in the ceiling, as its function is not reduced by any moisture which may become trapped in the cavity.

 

 

Finishing a 15 Year Old Pole Barn

Finishing a 15 Year Old Pole Barn

Reader BOB in WASHOUGAL writes:

“I have a 30’x60′ pole building. It was constructed in 2003. I would like to finish the inside with a concrete floor, Insulation, and sheet rock. My question is…How long do the posts last before they rot off at ground level? (I have a wooden fence that was built around the same time and 50% of the posts have rotted off at ground level!) I just don’t want to throw good money after bad. I want to end up with a permanent Building when I’m done.”

Mike the Pole Barn Guru responds:

Your fence posts rotted off because they were not treated to the same level of treatment as are your building columns. In fact, most fence posts are just dipped in a chemical solution, they are never actually treated under pressure. In many cases, fence posts are peeler cores (the center remaining after logs are peeled for plywood) which will not take a treatment to begin with, or they are a species which does not treat easily (or at all). I recently wrote an article about the lifespan of properly pressure preservative treated wood, which should put a rest to your fears: https://www.hansenpolebuildings.com/2017/12/will-poles-rot-off/.

Some nonstructural, yet important considerations – before your pour a concrete floor, make sure to install a good vapor barrier, which is well sealed. You should either unscrew the steel siding, place housewrap and reinstall, or spray closed cell foam insulation on the inside of the wall steel. In the event you create a dead attic space, make use of proper ventilation to prevent mold and mildew challenges later on.

I recommend you consult with a RDP (Registered Design Professional – architect or engineer) who can determine if your building is structurally adequate for the modifications you propose. Post frame buildings with steel siding, which have not been specifically designed for future drywall finish on the inside, often have deflection which is beyond the limitations of the gypsum wallboard – meaning the joints will end up cracking due to too much lateral movement. Chances are good your roof trusses are not designed to support the weight of a ceiling and will require some engineered upgrades in order to do so. You are about to make a big investment into upgrading your building, please do not take my recommendations lightly – as you stated, you do not want to throw good money after bad.