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Barndominium Interior Framing Details | MAD County Standard | Part 18

Welcome back to the MR Post Frame! Today we will be continuing our series on the MAD County Standard. It is very near and dear to us because it is a smaller version of our own personal barndominium. We're going to go inside and do a walkthrough, and I'm going to talk through how we frame the interior of a post-frame home. 

Interior Girts:

Interior girts

So we are to the part of the project where everything is all framed up in this two-story home. I'll start with the exterior wall. For the post-frame home, we use external standard girts, those are two by six girts on the exterior. On the interior, you can use two by four or two by six girts going up the wall. We use two by fours, spaced two feet on center, and then we use 5/8 inch drywall on our exterior walls. The concrete here will actually be the finished floor. It needs polished and finished up first. Once we're done with the exterior, we put our bottom plate on, which is a green treated two by four girt, and then we put the top one on. We have three inches of closed-cell spray foam put in, and then we start our interior framing.

If you're wondering why we do the spray foam first, well, we have an eight and a half inch wall cavity. So we do three inches of closed-cell spray foam on our walls, providing an air barrier, a vapor barrier, meeting the building code requirement of R21. It's a solid way to insulate your home, giving it structural strength. Once the spray foam is done, we run our two by four girts two feet on center. We use a laser to set our next girt, running it along the bottom of the windows to act as a nailer for our trims. Then, we use a 20 and 1/2 inch block to make the process quick and easy. We continue this, adjusting for different window sizes.

Plumbing + Electrical:

Framing your barndo

Moving on to plumbing and electrical, we plan for the main plumbing vent and think about how to run ductwork for HVAC. We leave a one-foot space between the bottom of our i-joists and the walls, providing a chase for venting and ductwork. For wiring, we use blocks to run electric wires, ensuring they are protected from drywall screws. In the utility room, we plan for the HVAC system, thinking about how to run ductwork and vents efficiently.

Interior Wall Framing:

As for interior walls, we use two by four 16" on center standard framing. We use green treated bottom plates and double top plates under the bottom floor provide stability. We add blocking for cabinets and consider load-bearing walls when using headers. In the garage, we use 2x4 interior girts and add a catwalk for attic access.


Barndominium (MAD County Standard) plans

The entrance into the house features a little entry bath, sink, and toilet, leading to a mudroom, laundry room, and a bathroom. We use a five-inch concrete slab with no need for footings below the walls. For load-bearing walls, we use double 2x12 headers.

2nd Level Flooring System:

Moving upstairs, we use 11 and 7/8 LVLs as a ledger board to carry the weight of the second floor. We have bedrooms, bathrooms, and open spaces with a temporary railing. For the flooring system, we use 9.5-inch i-joists, 3/4-inch tongue and groove subfloor, and plan for blow-in fiberglass insulation in the attic.

Price Breakdown:

Interior framing of a post frame building

For those interested in the plans, you can check our website,, in the plan section. These plans are available for purchase. If you like the layout, we'll provide a full walkthrough once the construction is complete. If you have any questions, leave them in the comments. We appreciate your support!

Thank you,

MR Post Frame

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