Friday, September 3, 2010

Pouring The Radiant Floor

Hi Folks,

I'll try to post updates a little more quickly, now that I have a digital camera on loan from a friend and co-worker.

Roughly a month ago, in late July, we "poured" the concrete floor.  Had we originally planned on a concrete floor some 2 years ago, "pouring" would have been a more apt description.  Since we originally planned on a pounded earth floor, made from clay sand, straw and lime, we went ahead and built the frame, roof structure, and walls, with the idea that the site-built earthen floor would be built after most of the construction was completed.

Well, life -- and financial reality -- sometimes intervenes, and it turns out that an earthen floor would have taken longer and cost more than concrete, since we would have to hire out the work if we wanted to get into the house before this winter.  We opted for a tinted concrete floor with radiant tubes for the eventual solar heating system.  With all the walls in place, there was a lot of pouring going on, but it was pouring out wheelbarrow loads that then had to be shoveled, raked, and worked by hand quite a bit -- hot, heavy, and very humid work!

Here are a few photos of the process, which may not be in exact chronological order...

Radiant Tube Layout -- SE Corner

First comes careful planning and preparation.  The gravel and sand under the floor is smoothed and leveled.  The vapor barrier goes down (polyethylene sheeting), and the insulation is carefully fitted and sealed on all sides.  We used 3" of foam board in two layers of 1.5" cross-stacked.  The radiant tube layout reflects the thermal losses expected in a given room, the potential for solar gain from south-facing windows, and the way the room will be used.  The tubes are laid out in several loops of between 200 and 250' length.  In our case, we put out 4 x 225' loops, and one shorter loop of about 180', which will get throttled back with a balancing valve.

Buildings lose heat to the outside walls, so the first part of each loop goes right to the outer wall, and the tubing is closer together there.  More heat is applied where more heat will be lost.  The spacing of the tubes is usually lower toward the center of the building, where the heat loss to the environment is much smaller.  In the above photo, huge south-facing windows are just off-screen to the right, so the tubing is closer together on the south side of the building to re-distribute any heat gained when sunlight strikes the floor.  Toward the left, and in the foreground, the spacing is further apart.

Cement Truck and Front Door
Here's the outside view -- the cement truck pours the concrete mix through the front door...

Filling The Wheelbarrow the waiting wheelbarrow.  These are maneuvered into place, where they are carefully dumped, taking great care not to damage the radiant PEX tubing.

Pouring the Concrete

A small piece of plywood is placed where the frame of the wheelbarrow would damage the tubes, and the load is carefully deposited where the spreaders need it.

Brad Dumps a Load

Even the lowly homeowner can help with this part -- no brains, just brawn needed for the wheelbarrow part!

Raking the Concrete

Since the wheelbarrow creates sloppy plops of concrete, a lot of hard hand work is needed to rake and spread and shovel the heavy mixture into place for an even, level floor.

Greg Spreads Concrete

This is Greg, the boss of the concrete crew.  He directed the layout of nails and strings to guide the pour and get the floor leveled and built up to the right height.

Ben Shovels Concrete

Ben Graham, as the general contractor on the job for the bale walls and floor system, helps shovel the concrete onto the bubble wrap insulation to create a thermal break between the floor slab and the ICF concrete grade beam that supports the walls.

More Hand Work

The concrete has to be leveled and smoothed out fairly soon after it is placed, partly for access to the area without damaging work already completed, and also to work the substance before it begins to set and stiffen up.

Toward SW Corner and Kitchen

Plumbing and drains are boxed in and protected

Smoothing and Leveling With a Scree Board

The surface is created with a LOT of heavy hand work, pushing, pulling, and spreading the stuff around to create a flat and level floor.

Work Your Way Toward The Door

Concrete work starts at the furthest corners, and work progresses toward the door, where the cement truck is filling wheelbarrows.

Hot, Heavy Work

As work progresses toward the door, it gets hotter and hotter.  The temperature outside is rising up through the 80's, but the concrete is now starting to warm up as it cures and hardens, so the inside temperature really takes off after a few hours.

Greg Power Troweling

Once the floor sets up enough to bear a little weight, the power troweler smooths the surface, and tends to bring up water from the mixture.  Experience is needed to get the floor flat and smooth, without pulling up too much water, which can change the color, texture, and durability of the final floor.

Finished Floor Toward SE Corner  

The concrete is tinted to a dark charcoal gray, mostly for passive solar gain.  It will lighten as it dries, then when the painting and finish work is complete, the surface will be polished and sealed, which will bring it back to a darker color.  By 6 PM it was about 120 degrees and very nearly 100% humidity in the house, even with windows and doors open!

Finished Floor in SW Corner

Walls still need lime-milk paint, and the exposed beams will get sanded and oiled, but we're getting there by great leaps and bounds. 

Next up -- finish plaster on exterior, and kitchen cabinets -- can't wait!

Till next time,