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Building a Post Frame Home | In-Floor Radiant Heat | Remington | Part 10

Alright, everyone, welcome back to the MR Post Frame. In today's video, we are going to go through the whole process of laying out and preparing all your in-floor heating tubing below a slab. I don’t want you to think that this is the only right way. We build post-frame homes, and this is just how we approach radiant heat when it comes to constructing them.


Essential step in in-floor radiant heat installation

When we do our in-floor heating, the first thing we do is build our structure. This is our preferred sequence, as in many cases, the concrete serves as the finished floor, and we want to avoid damaging it. We start by getting our gravel to the proper height, determined by the desired finished floor height. We use two-inch polystyrene insulation with a five-inch slab. The gravel or base is set seven inches below the finished grade. After bringing in and leveling the rock with a laser level, we compact it. Once done, it's time to lay down a vapor barrier. 

Vapor Barrier:

A vapor barrier is crucial as it prevents moisture from coming up through the ground and penetrating the slab. Adequate gravel allows water to drain through, minimizing moisture issues. We prefer a minimum of four inches of gravel for this purpose. For vapor barriers, we typically use a six mil plastic. While some may argue it's not thick enough, we find it sufficient for places without significant moisture problems. The choice between plastic thickness also considers cost, as thicker barriers can be substantially more expensive. To avoid punctures, it's essential to use fine gravel when compacting.


Floor vapor barrier

After laying the vapor barrier, we place two-inch polystyrene insulation. We don't tape the seams since there is already a solid vapor barrier beneath the plastic. Taping seems unnecessary, given that the insulation will be walked on.

Pex Lines:

Moving on to the in-floor radiant heat, we use half-inch oxygen barrier Pex lines in 300-foot rolls. Zones are created with a temporary wall, ensuring lines don't cross. Balancing flow through the lines is crucial, and we recommend keeping loops as close to 300 feet as possible. Flow meters can be added if needed.

Stapling Insulation:

We secure the insulation with a Malco stapler, using two-and-a-half-inch staples for two-inch foam board. This method is efficient and quick, especially compared to traditional methods involving wire mesh and zip ties.

Pressurizing Lines:

To keep the in-floor heat lines pressurized during concrete pouring, we connect them to a pressure gauge via an air chuck and air compressor. This helps detect any leaks early on.


Bardnominium in-floor heat DIY

We want to address some common questions. First off, we’ve been asked why we don't set up radiant heat tubing on chairs. That would be very difficult to do and to keep everything straight. Our method works well with the proper insulation layers, forcing the heat to go up toward the concrete. We used the same method with our personal home and it worked very well and I have been extremely happy with how our house has heated.

How to install in-floor radiant heat

Another thing to keep in mind is that we usually pour about 5 inches of concrete. With the PEX coming up roughly ¾ of an inch, I know that I can only drill down 3-4 inches for my projects. We also touch on the advantages of using closed-cell spray foam on the entire floor, although its cost can be prohibitive. The importance of a solid gravel base for drainage is also very important. Lastly, I recommend that you make sure you do stress cuts or relief cuts in the concrete.

In summary, this post outlines our step-by-step process for laying in-floor heating tubing beneath a slab in post-frame home construction. We appreciate your support and invite you to check out our Patreon for more detailed discussion.

Thank you,

MR Post Frame

MR Post Frame Patreon

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