On Tuesday my friend Grant came by to say hello and check in on the progress at The Casa. He made a comment along the lines of ‘that doesn’t look like any framed house I’ve ever seen…’ Since I have heard that several times since starting the project I thought I would take a minute to explain what Insulating Concrete Forms (ICF) are and how they work.

Although it is not yet widespread in our area, ICF represents a whole new set of options for new buildings, including residential construction. ‘Stick built’ or wood framed construction is still the prevailing choice, and it seems that most of the subcontractors are so accustomed to working with wood framed walls (read: they can do their work very quickly without a steep learning curve) that they don’t want to do anything but that. There have been some very welcome exceptions to that to be sure, and I’m sure in time more of the trades will continue to focus on this new building trend.

Even construction with brick or stone, like my father’s house, is essentially a facade applied over walls constructed out of (mostly new growth) timber. This is necessitated by the relatively low insulating value of brick or stone on their own. They are all fairly good thermal conductors, meaning that temperature changes on one side of the wall will be relatively quickly transmitted to the other side. The use of fiberglass or foam in the stud cavities of wood construction allowed houses with masonry construction to improve their insulation factor.

Decades ago a primary limiting factor for the use of concrete was aesthetics. While construction with concrete reinforced with steel was fairly cost effective and enjoyed more longevity than the average wood framed house, overcoming the ‘ugly’ factor was an issue. More common in commercial construction, penetrating the residential market was difficult when the primary option was to paint the concrete walls (or leave them bare). Couple this with the fact that concrete alone is also a very good thermal conductor, and it is no surprise that there remained relatively few concrete houses.

These insulation and aesthetic issues are both soundly addressed through the use of ICF construction. There are a number of different manufacturers of the blocks (Logix, Fox, Nudura) but all employ an elegantly simple approach. Instead of a single-layer concrete wall, or a layer of wood frame covered with a brick or stone veneer, Insulating Concrete Forms consist of three layers. A standard steel-reinforced concrete wall is sandwiched in between two layers of rigid foam insulation. The materials themselves are cost competitive with standard construction, and the systems are arguably more simple to construct than standard stick-built homes.

The standard building block (in our house at least, built with Nudura) is shown above. It is 8′ long and 18″ high. The inside and outside is made of rigid foam between 1 1/2″ to 2″ thick. The top and bottom of each form has teeth (like Legos) that allow them to easily fit together to build up the wall. In the space between the two sheets of foam are rigid plastic webs that space the forms apart in addition to providing an easy place to snap in the steel reinforcement (rebar). At the top and bottom of each plastic web are small plastic teeth that click together when you assemble the forms. These teeth keep the forms from ‘floating’ apart when they are filled with liquid concrete. These straight pieces are combined with corners and t’s (all with the same interlocking components) to essentially form the negative wall space. Once the forms are assembled (an incredible variety of shapes and configurations are possible by combining different forms) you literally pour in concrete from the top to form the core of the wall. The foam remains in place and becomes a permanent component of the structure of the building, providing a huge insulation boost among other benefits.

Concrete construction that doesn’t use ICF involves building the forms, pouring the concrete, and removing the forms once the concrete has cured - which adds labor to the process and takes away from the r-value of the finished product. So regardless of the system you choose, you wind up with a simple mechanism to build the forms (anyone who can assemble legos can put blocks together), great insulation for the walls, a good vapor barrier to prevent moisture from coming into the house, as well as ideal surfaces on the interior and exterior to attach siding or drywall. I can’t speak for the other systems, but Nudura has a nailing strip that runs vertically every few inches, and acts just like a stud in a wood framed house - allows for trades to drive nails or screws.

There is a great deal of information about and discussion on the benefits of ICF construction just a Google search away, but there are a few that helped us make the decision, including the low cost of heating and cooling, sound insulation provided by the thick walls, and best of all no wood to decay and need replacing down the road. Additionally, while the expansive pale green walls may look a bit odd to folks like Grant right now, by the time the construction is complete and the siding is applied the house will be virtually indistinguishable from a traditionally constructed home.

Hopefully that is helpful in understanding ICF construction, please don’t hesitate to ask if you have any questions or I can clarify anything.

Monday overnight there was a bit of rain, and it raised some concerns in Doug’s mind regarding the newly poured and sealed front porch.  He sprayed some water on the surface, and the amount of fall from the part of the porch closest to the house to the outside edge was not enough to keep water from running back toward the house.

We spent about a half an hour staring and thinking and reviewing options.  We could have the surface polished down, with more taken off the front edge than the back.  This could work, but it would be very expensive and would cause a significant difference in appearance as you moved away from the house due to the amount of aggregate that would be exposed by the grinding off of layer after layer on the front of the porch.  Alternatively, we could try to minimize the amount of water that would fall on the slab by carefully arranging the roof overhang, and caulking around the front door.

In the end, we decided that a fight against the elements (especially water) was not one the house would win in the long run.  Enter the sledgehammer.

I cringed a little bit upon the first swing, and even more when I realized that the blows from the huge hammer did little but make small dimples in the surface of the porch.  The ’state mix’ did indeed set up and get very hard very fast.  We tried for perhaps another 30 minutes with little progress before the next load of concrete was on the way.

We took a break from demolition and filled the holes adjacent to the master bedroom with concrete, and dumped out enough on the ground to fill the four additional short columns there that will support the master bedroom deck, and more around the back of the house to fill the three columns on the back patio.  I thought filling a bucket with concrete and hoisting it up to pour into the front porch columns was difficult, but adding eight steps up a ladder to the mix to reach the top of the 10′ tubes was yet another level of complexity.  A few hours later brute force prevailed, and all the columns were filled, leveled, and plumb with the house.

We then returned to demo, and made a little more progress when we raised the front edge of the porch with a hydraulic jack.  Raising the slab (as much as 7″ thick in spots) off of the gravel bed put a lot more stress on the slab and kept the force of the hammer blows from being diffused.  Bit by bit we chipped away, with the progress getting easier and easier the more of the slab we removed.  I got a good lesson in the power of steel reinforcement, as the rebar and remesh that was added made the removal of the slab nearly impossible in spots - the concrete literally had to be pulverized before it could be removed.

We didn’t finish until Wednesday morning, and not long after we had another load of concrete (this was ’shot-crete’ with fibers, designed for spraying on walls) arrive.  Doug had set up some forms at the beginning of the driveway, and we poured a slab about 40 feet long of varying thickness.  The driveway pour was relatively un-complicated, but allowed me to practice my burgeoning skills a bit.

A little rain at the end of the week was not unwelcome, all the hard work tearing out the porch left me feeling like I had been hit by a truck.  The framers should be here early next week with any luck, and the latest word from Micah is that we should go ahead without him.  He can polish around the walls if they are there - this will be more effort for his crew, but he didn’t want to hold us up any more.  The other benefit is any scuffs or minor damage inflicted by the framers or roofers can likely be polished out closer to the end of the construction.

We moved from our house in Kansas City on Saturday after a fairly brutal week of packing, cleaning, and little sleep. My advice to anyone considering moving ever again in their lives is start throwing or giving away things immediately.

Sunday we completed a few more miscellaneous tasks to get ready for some more concrete on the front porch and for the deck off of our master bedroom. We placed some 2×6’s to make the face of the front porch, and re-chalked all the lines to mark the eventual top of the surface. Once that was set up Jill and I caulked the inside of the form to patch up a few rough spots as well as to soften the lower edge where the lip of the top level will hang over the facing wall.

Additionally, we marked the location of the three more pillars on the back patio so that when we get another load of concrete we will be ready to fill them up to the right level. There will be six short pillars under the master bedroom deck, so we also dug four more holes that will eventually be filled with slugs of concrete to provide a footing for the columns.

It was fairly slow this morning, we started by getting the driveway forms started and standing by for a load of concrete. Sure enough later in the morning, we got word that three yards of ’state mix’ (a very rich mix used for the construction of roads by the state) was on the way. The only bad news is that we would need more than three yards if the entire remaining void of the front porch was to be filled with concrete. Doug got his tractor, and we leveled out a few loads of gravel so we would need about six inches to reach the top.

In an a great stroke of good fortune, the creamy, incredibly strong concrete proved to be just enough to complete the slab, we only had about a quart left over.

A few hours later we came back to seal the slab, and stripped off the forms so we could seal the face as well. The top portion which will be exposed looks fantastic (and just like our current bathroom concrete countertop), and the rougher face below will be covered by a step and some tile to match the surface of the flagstone patio.

I finally got in touch with Micah, and as expected he had been consumed by another job. He suggested that we go ahead and frame the walls and that he would compensate us for the extra expense of having to hand-finish the areas in the smaller spaces (closets, etc) once the walls were framed. I’m not entirely certain how we will proceed there, we are currently weighing the pros and cons of waiting against the somewhat unpredictable schedule of his crew and some of the other subs.

I’m in arrears for a few pictures, please enjoy…

We had planned for a relatively slow weekend to catch up on some paperwork, but got a lot more than we bargained for. On Saturday we spent a lot of time discussing the front porch and how we wanted everything configured. The original specification provided by B&G on the blueprints was (as we requested) closer to a Colorado ranch style, with a lot of stone and square timbers.

The more we talked about it, the less sense it seemed to make to have that kind of an entrance, especially the exposed wood beams given the other design decisions we’ve made over the past few weeks. So, given Doug’s proclivity toward portland cement and how much we loved the way the concrete columns at the back of the house turned out, we opted for a more…ahem…permanent solution.

I headed to Lowe’s and got two 12″ sonotubes (these were the Quikrete brand, colored bright yellow), and we measured the correct distance from the front door and from the walls on either side of the entrance. Soon enough we had big spray painted rings marking the eventual location of the columns. They will stand 7′ from the front wall of the house, and the top of them will be about 30″ off the height of the patio. As a means of paying homage to our current house, we will top each one with a stainless steel column to support the overhang of the roof. You can barely make out the column on the front porch here:

There will be one step down from there onto a flagstone patio of some type.

From there we started talking about the deck on the back of the house, and in case you’ve not noticed the trend just yet, wood is very much the exception at this point. We were planning to go with Trex to keep the need for maintenance as low as possible, but having wooden beams as the infrastructure means we would still be prone to all the cracking, warping, and other issues with lumber.

So a few hours later we had fully baked a design change that involved pouring three more concrete pillars (8″) in closer to the house, and framing the rectangular part of the back deck in steel. The deck will essentially float on the six columns, potentially with some small anchors to hold it to the house. Once the steel is framed in, we will run a short loop of pex tubing and pour probably 4″ of concrete to comprise the surface of the deck. I doubt that we will heat it much, but probably just enough in the winter to keep the snow and ice melted.

The deck off of our master suite will be essentially the same, and we will have a catwalk of some sort in an “L” shape to connect the two together. I doubt that the catwalk will be concrete, and I’m not even sure if we will do that part in the short term.

These changes required us to provide a little more infrastructure for the framers than we originally planned, so we went ahead and built the forms for the back patio (out of the walkout basement) as well as the front porch. The back patio was pretty simple, just a big square with the right level of slope away from the house and a little bit of steel remesh dropped in for support. I also wrapped each of the existing three columns with one turn of sill sealer, which is a thin layer of foam. This will give the concrete a little room to expand and contract without the columns and the patio putting too much direct pressure on one another. After that I wrapped each column with Glad Press n’ Seal wrap to prevent any splatter from getting on them. Holla for new uses of kitchen products!

With the back patio poured, the framers will be able to work on scaffolding and attach temporary roof supports to the existing concrete columns, and they can do the same on the front porch.

Tuesday morning we ordered about 5 yards of concrete, and first dumped just a little bit inside the forms on the front porch. Using string lines running between the front walls on either side of the entryway, and from the front of the forms to the front wall of the house, we positioned the tubes in and put just a few inches of concrete in them to hold them in place.

We then directed JP around to the back and proceeded to pour the back patio. As usual, my role was mostly handing Doug things, but I did get in and help him pull the wet concrete into place for him to finish it. Once the patio was basically flat and he was ready to do the final finishing, JP came back up to the front and dumped the last of the wet concrete inside the form on the front porch. I then spent the next hour filling up a kitty litter bucket with wet concrete, hoisting it up on my shoulder, and pouring it inside the tubes. Fairly exhausting, but very rewarding when it was all done. When the tubes got close to being full, I stirred each one around with a fencepost and slapped on the sides of them to get all the air bubbles out. The viscosity of wet concrete is pretty amazing, especially when you have five feet of it filled up in a narrow tube.

By this time the back patio was very close to being finished, so we marked the spots for the three new columns closest to the house, and inserted three short “L” shaped pieces of rebar (about 2 feet long) for support, as well as one longer one (about 10 feet long) with a similar bend at the bottom. This steel has the tube slipped over it before the concrete is poured, and provide reinforcement to keep it from leaning either way.

Once things settled down a little bit I drove into town to get the last three 8″ cardboard tubes that will be placed up against the house. When I got back, Doug was back in the (still mostly unfilled) front porch forms, shoveling and sweating like mad. It turns out Citywide delivered a few extra yards of scrap concrete, and he was working on distributing it inside the forms. It was fairly ‘hot’ (ready to set up) so pretty tough to work with, but we brought it up level with the top of the forms sloping slightly back toward the house. The top of that concrete is still about 5 inches below the final surface of the patio, so we will next fill up with gravel, level it off, and then pour a final slab on top that will make up the finished patio surface.

I tried in vain to take some pictures, but the camera battery did not cooperate. I’ll have some more when I get back this weekend.

The only other point of interest is that we haven’t heard yet from Micah, he was tentatively scheduled to polish the floor on the main level on Tuesday (three weeks from the original pour). We’re now in the middle of a rain out courtesy Gustav, so everything will be pushed back several days at least.

If you don’t hear from me soon it is because I’ve been kidnapped by a lumberjack for threatening his livelihood…