Insulating Pole Barn Ceiling

[TC65023]

Smallplot: there was a lot of information posted in my initial post, it is easy to overlook some of the detail, I suspect your glasses are fine.

The building will be divided into two basic functional areas, the main garage vehicle and equipment storage area which is 30X45 and the 12X45 finished shop, restroom and mechanical area. The main garage would be intermitantly heated as needed and the rest heated or cooled all year long. The hot water heat will be provided by my Shaver outside wood boiler unit. I think radiant heat with Pex piping installed in the floor slab is the economical and best way to heat the building. The air conditioning system for 12X45 area will likely be a efficient split system consisting of condensing unit, coil, blower and supply ductwork.

The two areas will be separated by a common insulated stud wall from floor to the bottom of the trusses. This wall will effectively reduce the truss span and improve loading somewhat. I will install a metal panel ceiling in the garage and may use a suspended ceiling system in the remaining areas for access and noise control. I have already installed 2x6 ceiling purlins secured with metal joist hangers at 2 foot centers between the trusses in the entire building.

 

[TC65023]

I've pretty well decided on the ceiling construction and insulation system I will be using in my building.

I need a little input for options on my exterior wall construction and insulation system. I already have 160 sheets of salvaged 4x8x1.25" thick polyiso, foil faced both sides, that I intend to sandwich in two or three layers on the walls. Since I have to cover the insulation with a fire barrier meeting my insurance company's requirements, I think I will use OSB FF. It's cheap, durable and will provide a substrate to secure the vertical painted metal panels. I could save about half the cost by using drywall in lieu of OSB, but it's subject to moisture and impact damage and is not a nailable substrate for the metal wall panel installation.

The building already has 2 inches of poly faced fiberglass in the wall for a condensation barrier. It is installed between the exterior metal siding and horizontal 2X6 wall girts.

I was instructed by the pole barn builder to provide for passive ventilation and separation between the condensation barrier and any future wall insulation system I installed, so there could be no possiblity of trapped moisture rotting the wood structural components or rusting the metal siding.

I intend to address the issue by installing vertical 2X4's full height on 2 foot centers with the 3.5 inch face secured to the horizontal wall girts. The top of this 1.5 inch furring would be open and passive vent above the ceiling line into the attic. I would sandwich two or three layers of the polyiso insulation and cover with OSB FF. My biggest concern is the thickness the (3) layered system with the OSB being 4.33 inches and the number, length and cost of screws needed to secure all to the vertical furring. The painted metal panel installation will be easy since the OSB is nailable. Also, I intend to have several cabinets securely mounted on the perimeter wall. I think the best way to address the cabinet installation is to install a horizontal nailer between the 6X6 posts (on all walls) at the proper elevation just behind the OSB sheathing.

Any concerns or does someone have a better idea of how to do it?

 

[KennyG]

Just to add details to my approach. I have polyiso in 1.5" and 2.0" thicknesses. I have installed, in the walls one layer of 2" and two layers of 1.5" with the seams offset. The last layer is installed between horizontal 2x4 purlins that go between and are flush with the inside pole surface. I will use these to support the interior metal panels.

Does your fire code accept the metal panels as a fire barrier, or do they require drywall/OSB in addition?

 

[TC65023]

KennyG: good question, I'm going to ask my insurance company again about using metal panel as a barrier. They are a stogy old company, set in their ways, LOL...like I am! I suspect they won't budge any, but it won't hurt to ask, it will save a lot of money and time if they approved it.

 

[KennyG]

Fire barriers are based on tested configurations that prevent fire spread, and if I recall correctly a metal barrier should be as good as fire rated drywall barrier. Try that out on your insurance guy.

Above someone speculated about enclosing part of the barn and heating it. I considered that, but decided it would really restrict the space and when I looked at cost it wasn't much more expensive to insulate the whole pole barn. I'm putting in a gas furnace and I will just distribute air to the shop area and let the rest be a little colder.

 

[TC65023]

KennyG: I considered the separate heated enclosure idea, but came to the same conclusion it was just too limiting for my anticipated use. I wanted full use for the entire area and it wasn't that expensive compared to the benefit.

 

[Oldmopar]

Hello, these are just my experiences... If your insurance company allows (and I hope they will) staple 3 mil poly to the roof perlins and install your steel over that, then blow in whatever R value you are looking for. This would probably be the cheepest and definately the easiest install. You have a good idea for your walls, same thing I have done in the past. I would suggest getting a case or two of sprayfoam in cans and using that around the edges of your foam sheets and where they butt up to each other. Doing so almost makes it one large sheet and really cuts down on air intrusion. Good luck and sorry for being so long winded!

 

[TC65023]

KennyG: I live in a predominately rural, very conservation (cheap) county that has no adopted building standards or fire codes. So that leaves the decision process pretty much up to the construction standards of insurance company and what they will accept. The may actually might work out in my favor with a little luck, but I'm not counting on it. I will let you know how that turns out.

 

[TC65023]

Oldmopar: I agree with your recommendation of sealing the edges of the insulation sheets. Since I will be layering the materials, do I need to seal just one layer, or each layer? I'm not sure it's necessary to seal at other butt joint locations since I will be installing the sheets in three layers and staggering the joints.

 

[TC65023]

KennyG: how are you securing your wall insulation sheets in place? I was thinking about screwing my first two layers (2.5 inches total) to the vertical furring and then using adhesive to temporarily hold the last layer (1.5 inches) in place between the the interior horizontal girts supporting the fire barrier material and the finish metal panel.