Partitions Half Up

Today we got all of the partition walls, the inner walls of the tiny cottage up to the wains coat level. I’m going to do the same trick of foam boards and a pour on top to produce a bond beam and perfect level across all the inner walls as we did for the outer block walls. That worked extremely well. The outer beam was already hard this morning and we peeled off the forming foam boards that were in the way of today’s work.

In the photo above Will, in the orange coat, is standing in the bedroom next to the wall that will support my marine aquarium. He’s helping Holly make forms for the top of the other bedroom wall. Along the south wall Ben is making wire toggles out of form wire and old screws. We’ll use those to hold the forms tight while we pour. The wire will remain in the cement and later be used to bind the stone facing to the CMU block wall. Closer to me you can make out hope who is using nylon zip ties to connect rebar together along the top of the front west partition wall.

This shows the key in the channel block bond beam that I described yesterday. The first thing I did in the morning was to stike off the bur. The groove, or key, will help lock the next course of mortored concrete blocks to the smooth surface of the bond beam.

Here I’m removing the inner insulation along the poured vertical concrete wall. First I knocked the top of the board with the rubber mallet to help break the bond with the concrete. When we setup the forms we had sprayed the pink foam board with WD-40 oil to help it release but it still had some adhesion due to dings we put in the foam when pushing the stiff 0″ slump concrete down into the insulated forms. A putting knife worked for opening the space at the top wide enough for me to get my fingers in and then the foam board came off well.

Removing the insulation allowed us to see how well we’d done with the vertical wall pour in the forms. Most of it looked great, a few small air bubbles. There was only one place where we had failed to vibrate that there were bubbles bigger than a tenth of an inch and even that spot was not too bad. One change I would do on the pour would be to use a 4″ slump concrete next time rather than the 0″ slump we used. That was too stiff and required a lot of working.

What is slump? Slump is the measure of how liquid a concrete is after mixing. The measure is made by filling a 12″ cone and then placing it, large end down, on a flat surface. The cone is carefully lifted off and set next to the pile. The slump is the measure of the difference in height between the top of the cone and the top of the resulting slumped pile of concrete. For example, a very stiff mix won’t slump and is said to have a slump of 0, that is zero inches of drop in height. A slump of 3 means the pile dropped down 3″ below the top of the cone. A slump of 12″ would be a self-leveling concrete that pours out virtually like water. A higher slump (e.g., 12″) is more liquid and thus easier to move around but also harder to keep in if there are any gaps in the forms. That higher slump concrete is also weaker when cured because it is generally achieved by adding extra water to the mix which does not chemically react with the cement. A lower slump (e.g., 0″, 3″, etc) is stiffer and when cured it will be stronger but is harder to work. The slump can also be increased without adding water by adding in a flow agent. Soap works for that because it reduces the surface tension of the water allowing it to mix better with the dry materials. This is a bit of a simplification but conveys the essence.

The reason we haven’t removed all the insulation is that it is mid-November in the mountains of northern Vermont… It has been unseasonably warm (and I want to thank all of you who are running your SUV’s for us!) but it could get cold at any time. The curing concrete is very susceptible to freezing so I want to keep it protected for as long as possible.

Whether dry stacking or doing a mortared wall it is important to set the first course of block in a base of mortar so as to assure all the blocks are level, even and the irregularities of the floor are smoothed out. Getting the mortar just the right stiffness and stickiness is key. Some book advise the amateur (e.g., me) to hire a professional for this difficult first course. But why give up all the fun stuff! Why would I ever want to pay a professional to make my mistakes for me?!? Actually, it isn’t as hard as they make out. Twice I did redo a section but with practice you get the hang of it. Concrete is a very forgiving medium, until it cures. :)

Of note in this photo is that the partition block wall is not touching the outer concrete wall. The reason for this is that I am leaving a gap around the base of the walls for running utilities. I did a 5″ gap. I should have done a 7.5″ gap due to the sizes of block. *clearing of throat* — Live and learn.

One course done of the reef tank support! Looks great. The aquarium will be built into the wall between the bedroom, where I’m standing to take this photo, and the bathroom, where the pile of concrete blocks is sitting. Access to the tank will be via standing in the bathtub thus keeping all of the water in one spot and out of the bedroom/office/theater. As much as I like aquarium keeping, I also like sleeping in a dry bed.

Partition blocks are half width but full height and length (nominally 4″x8″x16″). The bottoms of the hollow cores have a bit of weak cement in them. Since I am filling cores for strength I wanted to be able to pour and plunge concrete down the hollows. Thus we broke out the cement in the bottoms of each block. This is an excellent job for a three year old. You could do this while plunging, with a rebar rod, but I have a second reason for doing it ahead of time: When laying up mortared courses of block I get a better bond if the core is empty so cement from below flows upward. This is particularly an issue on the first course mortared to the floor or to the bond beam.

In the reef tank support there is no steel, no rebar, no metal of any sort. This is because marine aquariums use salt water. Salt contains chloride. Chloride rusts metal. When metal rusts it expands. When it expands it cracks the concrete. Baaad idea as my sheep would say! So I mortared the entire shelf with PVA fiber reinforced mortar without rebar and also added Aqron 300 and CPT-2000 to help protect the concrete from the invariable spills of salt water.

Yesterday I had been dubious about the idea of dry-stacking the partition block because it is so narrow but today, after getting my initial courses all mortared and firmed up I tried it on some other partitions and it worked great. Here is Ben, cutting a block and fitting it in place. Ben cut several blocks with a hammer and chisel, two of which went into this dry stack walled. He got them so tight and so right that you couldn’t slip a sheet of paper into the cracks. Very impressive!!!

After the walls were up Will, Ben and Hope filled them with cement, tamped them down and we added vertical rebar strategically placed to lock the blocks together. One interesting difference between half width (partition) blocks and standard blocks is that the partition blocks have three cores while the standard blocks have only two.

Prior to setting up the forms for the top channel pour of the lower partitions we set horizontal rebar in place. This cross bar is tied to the vertical rebar with nylon zip ties. The zip ties are not for strength, they’re just for holding it in place during the pouring so it will stay the proper distance from the edges and blocks. The stick of wood was Hope’s addition that I’ll need to remove before we actually pour as I don’t want wood in the cement. She’s pretty clever…

This is one of our windows. No, I did not break it. Nor did anyone else in our family. It came that way. I got 66 of these from the old IBM offices in Essex Junction for $5 each – what a deal! This broken one was free, #67. We taped it up and are using it as a jig when setting frames and block. That way if we should break a window it won’t matter. I would loath to break one of the real windows. Later, someday, when I’ve used up all the other windows, I may place a new sheet of glass in this frame. It’s is a very nice, heavy duty aluminum frame. Some of the windows are tempered and some are plate glass like this one. I also salvaged a 10’x5′ double pane picture window – I haven’t figured out yet where that will go.

Our old house, the antique colonial era cape, has very few windows on the south side. In fact, being from that time period it has very few windows at all. This tiny cottage will have almost as much window glazing as the entire big old farm house. More importantly, they’ll be super windows that I’m making. They’ll let the light and sun in and keep in the heat – important in our climate. On the outside there will be one of these types of windows. On the inside there will be another one of these. Sandwiched between the two panes of glass will be several layers of Tedlar shrink plastic separated by 1/4″ gaps. I built some of these 16 years ago and they’ve performed beautifully.

In the final house I have another trick I have always wanted to do. Concentric rings of energy. In the outside the temperature varies around here from -45°F in the winter to 86°F in the heat of the summer. Yes, I know you southerners bake through much hotter summers but to me that is hot! Our issue is not so much the summer. It is the cold of winter. -45°F makes you want to hold your breath until spring. Then add typical winds of 30 mph to that with winds of 70 mph not being uncommon and you feel like an icicle. So I want to wrap the house in an environment that does not drop below freezing. To the northwest, north and northeast it will be the mountain that enfolds us in it’s warm embrace – thus the earth-sheltered design and the use of concrete and stone. To the few windows on the southeast and southwest we’ll have super windows. To the south it will be a greenhouse which during the day collects energy for us and during the night we close off from the warmer house interior. In the core of the house we’ll have a large tank of water – More on that later.

Back in the early 1990’s I did a test of this with the farm house. We build a simple lean-to 60′ long greenhouse with 2×4’s and sheet plastic along the south side of the house. During the day we opened windows and doors to allow the sun’s warmth to circulate inward. At night we closed the house off from the greenhouse thus retaining the heat and minimizing condensation in the greenhouse from the house air. One sheet of plastic kept it above freezing all winter. The next year we added a second sheet and that kept it above 40°F. The next year we brought it up to 3 layers and that kept it above 45°F. The idea works even on so simple a scale. With this final house I hope to improve that even more – one of the major drawbacks of the simple greenhouse we had was that it lacked sufficient thermal mass. This house of stone will fix that.

When working hard it is important to take regular breaks for fluids and an apple or something to keep you going. This is Hope, our ‘water girl’. She manages the tea, hot chocolate and lemonade concession, making sure we all get a drink from time to time.

Today Will figured out a neat trick for cleaning the Husky brand mortar mixer that we use. We normally put the paddles into a bucket of water and let it stir for a little while before hand cleaning both the bucket and the paddles. This time he threw a cloth rag in. He says that worked but he would like to find something even more bristly he could use with it.

62°F/42°F Partly Sunny