Radiant Floor Tubing and Concrete Floor Pour

This was the week that it all came together. Here’s a review, day by day.

Monday – This was vapor barrier day. A vapor barrier is typically a sheet of 6 mil plastic. Although it is often described as a vapor barrier, it is really a vapor retarder. Even if the plastic sheeting was completely air tight with no puncture holes nor seams, there’s still some vapor that will penetrate through the plastic. So, let’s just say that the vapor retarder blocks most of the moisture from escaping and prevents most radon gas from escaping into the house.

The plastic sheeting can be purchased in huge sheets, but I elected to go with a roll that was 8′ wide by 100′ long. This made it easier to apply with the inside walls being close to 7′ long. There was quite a bit of overlap as it was rolled toward the center, but there’s nothing wrong with having extra overlap.

Tuesday – Tom came by to help lay down the reinforcement wire. We used 4′ x 8′ sheets of 6″ x 6″ reinforcement wire. This made it easier to lay down with very little cutting. The wire gives tensile strength to the floor and provides plenty of places to tie down the 1/2″ radiant floor tubing.

Wednesday and Thursday – Four sections of 300′ radiant floor tubing were laid down and wire tied. Notice in this photo that most of the tubing is positioned near the outer walls of the house. This concentrates most of the heat in the areas that have the greatest heat loss. Also, the cordwood walls (thermal mass) will soak up a lot of heat and slowly re-radiate the heat back into the house. This helps keep the temperature in the house constant.

This system is the secondary source of heat for the house. (The primary is the solar heat storage system located in the sand bed.) When the need arises for quick heat, these tubes will heat up the concrete pad in a hurry using a separate boiler. (The sand bed on the other hand is a very large flywheel and takes months to charge.)

Friday – The day was spent taking wall panels down and getting prepared for the floor pour on Saturday. The 1/2″ radiant tubing was pressurized and tested. This is a good idea for a couple of reasons. (1.) You do not want to pour a concrete floor to find out later that you’ve got a leak in the tubing. (2.) Pressurizing the tubing will help keep the tubing solid while wheel barrows are moving about and give you an immediate indication of a puncture if it occurs while the concrete is being poured. (We kept an eye on the pressure gauge throughout the pour.)

Saturday – I didn’t sleep very well. I kept wondering if everything was really ready for the concrete. There’s only one chance to get this right! Did I make any mistakes or forget anything? What about the plumbing? What about the tubing in the sand? Will the sand storage bed work? Did I compact the sand enough? Did I add too much water to the sand? Will the sand bed ever dry out? I guess eventually I will have the answer to all of these questions.

I got up at 5:30 AM and added some pressure to the tubing and did my final check list. Things were looking good except the weather. Rain was on the way. Rain would not be a factor in pouring the slab, but the extra moisture in the air would slow down the setup time of the cement. (A roof framed house keeps the weather out of the equation while doing any concrete or masonry work. We would have been delayed at least a week in doing this pour if we did not have a roof.)

The crew (Tim, Barry and Gary) arrived right on time at 7:00 AM. The concrete truck was suppose to arrive at 7:30 AM, but didn’t show up until almost 8:00 AM. (I guess this is not too unusual.) Things went fast once the truck arrived. The crew did the pouring and screeding while I went around making sure the reinforcement wire was pulled up into the concrete. (Leave the screeding and floating work to the experts.)

With the panels off the sides of the house, most of the concrete was poured using the truck’s chute except for the four back sides of the house and the center. That required the wheel barrow.

After the trucks left, it was time to wait…and wait…and wait. With the plastic laid down under the concrete and rain in the air, the set up time went on for hours. It wasn’t until around 2:00 PM that the power trowel could be put into action. Adding insult to injury, I requested a very smooth finish to the floor. Since we are not planning on having any floor coverings, the floor had to be nice and smooth. (Plans are to acid stain the floor.) Finally by 5:30 PM the final troweling was completed and the floor looks great!

On a final note, a very special thanks goes to Tim, Barry and Gary for their wonderful work and expertise. If anyone around the La Crosse area is looking for concrete work, I highly recommend them. I will be using them again when we get around to building the garage/workshop. (Don’t even begin to ask what year that will be. There’s still a cordwood house to build.)

After all these weeks of work, it’s wonderful to have a solid floor!