Dry stack concrete block construction

While doing some research about laying blocks in anticipation of building our root cellar, I came across drystacked.com and thenatualhome.com. I also found a U.S. Dept. of Agriculture bulletin entitled Construction with Surface Bonding. This information convinced me to use this method.

Today, I had opportunity to actually experience dry stacking concrete blocks. Having set the first course in mortar on the foundation yesterday, making sure it was level, allowed me to get a lot of blocks put into place. As I stacked each block today, I checked it for level along and across the wall. Often, when it was out of level across the block, just turning the block around brought it back in the bubble.

I started on the corners, stacking the four corners to five blocks. Then, I set blocks between the corners until I had the walls built up to five courses by lunch time. Some of the last blocks on a side took a little persuasion to get to slide in, but they all went.

I’m building my root cellar walls ten courses high. By the time I stopped today, I had two walls at ten courses, one long wall at seven courses, and the other short wall ten courses at one corner and eight at the other corner.

Along the wall near the house, I applied the surface bonding cement (Quikrete Quikwall) on the outside of the blocks. I won’t be able to get behind this wall to do it later. So, after laying the first four courses, I leaned over and troweled it on. After laying three courses, I added more above what I’d put on before lunch. Based upon how this bit went on, I think surfacing the rest of the walls shouldn’t be too difficult.

Dry stacking the blocks was simple enough that even Jessica helped. She came to see what I was doing this afternoon and wanted to help. I showed her how to check level on each block and how to put them on the wall. She worked for a while and set several blocks.

Root cellar: starting to block the walls

Another post on the root cellar? Well, that’s the part I’m working on until I get it far enough to work on the next thing.

The floor turned out nice. I took the plastic and tarp off of it Monday. The plastic kept moisture on the surface while it was curing. This was good since I don’t have a hose near the site I could’ve used to mist it. I’m pleased with how the floor turned out. It’s smooth enough to be easily swept.

Last week I ordered and paid for enough concrete blocks, mortar mix, surface bonding cement, and concrete mix to complete the root cellar and crawlspace perimeter (if I figured correctly). Yesterday afternoon the first load was delivered which included six cubes of blocks (90 blocks per cube) and most of the bags of mixes. The rest of my order is scheduled to be delivered next Monday.

Dad helped me stack five cubes on the root cellar floor after they were unloaded from the truck. That was 450 blocks – approximately 16,200 pounds worth that we moved. We were able to set up a ramp down which we slid the blocks one at a time into the root cellar.

Today, I began the root cellar walls. I’m dry-stacking the blocks. This methods involves setting the first course of blocks in mortar on the foundation, no mortar between blocks. Then, the blocks are stacked without mortar in succeeding courses. Once they are stacked, some of the cores are filled with concrete and rebar for additional strength, after which both surfaces of the walls are coated with surface bonding cement. This makes a strong, durable wall. It’s also a little easier for the novice builder who isn’t a mason.

By the time I finished this evening, I had the first course set. It is important for this course to be level – that’s the main reason for the mortar, actually. After I double-checked my measurements, I laid out the blocks for the first course. I checked for square and that everything lined up. Then, I began to move the blocks again, mix mortar, and set them, checking and double-checking for level in every direction. Tomorrow, if the weather is nice enough, I’ll begin dry stacking blocks on top of the first course. In all there will be ten courses. I may mortar after the fifth course just to ensure things are level, but I’ll hold off on that if it’s not necessary.

 

Root cellar: the floor is poured

The ready-mix truck arrived about 8:30 this morning with 4.5 yards of concrete for the root cellar floor and footers. I figured it would be simplest to do a monolithic pour rather than separate pours for footer and floor. Besides, doing so would’ve involved smaller batches of concrete and extra hauling fees ($75 if I received less than 4 yards at a time).

The driver was able to get the truck right up to the edge of the root cellar excavation and pour it all from one point. I had made sure ahead of time that there would be access from two different sides so that the driver could decide the best point(s) for unloading the concrete. It took less than 15 minutes to dump the concrete into the forms. I then spent five hours finishing it.

The excess concrete was not very much, and it was screeded over the forms at the far end of the pad. My dad helped spread the concrete as it was unloaded from the chute on the truck and then helped me with the screeding.

I constructed two bull floats for floating the surface of the concrete after it was poured. They worked well for this purpose. One was made out of an old mop, a board screwed to it’s end, and an extra handle attached. The other used a 10 foot long piece of 1/2 tubing and a larger board attached to its end.

I inserted sections of rebar with a J-bend into the concrete along the back wall and the side walls. These are spaced to fit within some of the block cavities. In these cavities, I will insert more rebar once the walls are up and fill them with concrete. I’m going to dry stack the concrete blocks and then use surface bonding cement on both sides. This method is supposed to be stronger and easier for a novice than traditional mortar masonry.

Once the concrete set up enough, I was able to trowel the surface to smooth it out. This went quite well. The cellar was in shade while the concrete was poured and floated. Then, the sunshine worked its way across the floor gradually. The area in the sunshine set up faster while that in the shade took longer. This was good because it gave me plenty of time to trowel the surfaces that were drying faster rather than having the whole thing setting up about the same time.

After finishing with the trowel, I covered the slab with plastic and an old tarp so that I won’t dry out too fast and will hopefully cure better than it would otherwise. I’ll leave it alone until Monday or Tuesday. The blocks for the walls are scheduled to be delivered Monday afternoon. So, if the weather permits, I may be able to start laying some block on Tuesday.       

Plaster samples (part three): a new mix applied to a bale

After testing our previous samples, the boys and I mixed up another batch and applied it to the other side of the test bale (actually, it’s half of a bale because I sawed it in two lengthwise to double the surface area for our samples). For this mix we used 4 measures of sand, 5 measures of clay-dirt, four loose measures of chopped straw/hay, and enough water to achieve a nice consistency.

The surface of the bale to which we applied it had not been trimmed. So, it was quite rough. However, the mix was wet enough that we could press it into the bale quite well. The plaster sample is drying now. After it is dry, we’ll apply a second coat to it to see how well it adheres to the first. Applying the plaster by hand leaves a rough texture which is supposed to help the next coat to bond well with it.

It’s actually quite exciting to have the opportunity to use some of our own soil for the plaster on our walls. We hadn’t expected to be able to do so – I was going to buy dry clay powder from a pottery supply dealer. I expect I’ll still buy some clay for the finish coat. We’ll use a white kaolin clay with some yellow pigment added. We’ll be figuring proportions out later.

If you ever get the chance, you ought to try putting some mud on a straw bale. It feels good in your hands, and it’s kind of fun.

I’ve been adding videos to my posts. I think there are things that can be understood and seen in a video which are hard to translate to text. So, here’s a video of mixing and applying our plaster sample:

Plaster samples (part two): testing

The plaster samples we applied to a test bale earlier took a while to dry because the bale was in the garage without much air movement. They did dry fine, though. So, I took the bale outside yesterday afternoon and, with the help of some fine younguns, tested how well they adhered to the bale and their strength.

Both samples dried nice and hard. They really adhered to the bale well – no problem there. The mixture that was 2 parts sand and 1 part clay had a grainier texture, and sand could be rubbed off of its surface. The addition of wheat paste might have helped bind it together a bet more making it less likely for sand to rub off. I hope to try a sample with wheat paste soon.

I made a short video documentary of our testing process:

Root cellar: concrete forms in place

Although it was overcast this morning, it didn’t rain today. The sun finally came out from behind the clouds around noon. I worked in the hole all day. This morning the damp clay in and around the work area stuck to my shoes all the time. With the sun out this afternoon, I didn’t have any stick. Either the sunshine dried things just enough or this clay is allergic to sunshine.

I didn’t use the backhoe today. I moved a fair bit of dirt with a shovel and a grape hoe, though, in order to get make sure the bottom of the hole was level. It was close, thankfully. There was some dirt along the edges that needed moved so I could set the forms.

For the forms, I used some boards Danny salvaged from an old mobile home he helped demolish. They are fat 2x4s, measuring about 1-3/4” x 4-1/4”. I had to pull some old staples out of them, and then I was ready to set them in place. I also cut some stakes from some scrap boards I had near the house.

I started in one corner and leveled the forms from there. By lunch time I had one end and over half of both of the long sides done. Since it’s important to put the outside corner of the root cellar walls in the right place, I had to take some measurements from the west side of the house. Determining the precise location of this corner is somewhat difficult. However, using a ladder strapped to the floor joists in the house, I was able to measure eleven feet out from that side of the house and set a stake at the inside corner of the root cellar.

To figure the outside corner, I measured from the stakes I had set previously. It soon became apparent that I didn’t have things laid out square. It was time for lunch at that point, so I left it till this afternoon. Armed with an exact measure of the hypotenuse of a right triangle with two eleven foot sides and a framing square, I adjusted one of the corners on the forms I had already set. Once I did that, the diagonal measurements came out correct – things were square.

It didn’t take long this afternoon to finish the forms. I built a small box to go around the floor drain. I’m not sure exactly what the usual way is for pouring a floor with a drain. I figure that I can pour everything around and up to the form around the drain with enough slope for water that ends up on the floor to head for the drain. Later, I’ll cut the drain pipe at the right level, mix and pour some concrete, and fill the last section of the floor around it.

The next step is to dig a couple inches deeper near the forms for the footer and lay out some rebar in the footers and floor. I don’t think that will take too long. Once that’s done, we can have the ready mix truck come out. The only thing that may interrupt the timing of things is rain. If we get too much rain, I’ll have to wait for things to dry out before the concrete truck can get close enough to the hole. I hope the weather cooperates so we can pour the concrete next Tuesday or Wednesday.

Root cellar: second excavation

On Monday I had a neighbor haul a friend’s backhoe to our place. This is the same backhoe I used a year ago to excavate the root cellar. Since I didn’t get the floor poured and walls built last summer, the winter rains washed a lot of dirt and debris into the hole. I started shoveling it out by hand, but found the task daunting. The backhoe has saved a lot of time.

I was able to move clay-dirt from one pile near the hole on Monday, but then it began to rain. I didn’t work with the backhoe on Tuesday, but yesterday I was able to get at it. It was a little muddy on top still, but I wanted to get the job done.

Today, I plan on finishing with a shovel, moving the dirt left in the hole out of the way. Then, I will begin building the forms for the concrete. If the weather cooperates, we’ll pour and finish the floor next week.

Milling porch posts (part 2 with video)

Sunday of this week was a nice day. Dad and I had already milled 15 6x6 posts for the porch, and I decided to get the rest of them milled. Last week I 3 new Oregon saw chains from from Treestuff.com (3/8” pitch, .058 gauge, 115 drive links). They shipped them out right away and I received them on Friday. These were regular cross cut chains with a 25 degree angle on the teeth. Sunday morning I ground the first one to 20 degrees with a 50 degree hook angle. Generally, ripping chains are ground to either 0 degrees or 10 degrees. I wanted to try it at 20. It worked fine. I’ll probably try the next one at 10 degrees so I can compare it to this one.

I purchased a new video camera (Canon FS100) for creating a video documentary of the house-building process from this point forward. Using the sawmill provided an opportunity to use it. My dad shot this video of me finishing one of the posts.

I’ll probably share occasional videos on the blog. The editing process for the documentary of the project will happen later.

After milling on Sunday, we now have 22 posts ready for the porch.

I still have some more cedar logs to mill, but I’ve not decided yet what dimension lumber/beams would be most desirable at this point. I’ll also need to haul some beech logs from Gill’s place and mill them. I think the milling will be put on hold for the next three weeks at least, though. I’m hoping to get the root cellar floor poured and the walls blocked and then to get a perimeter of concrete blocks laid around the timber frame. These will enclose the crawl space and help support the porch and straw bale walls.

Milling porch posts

Last week while we had some nice weather, we started milling some of the cedar logs into porch posts. The posts are 6x6s. Sure, 4x4s would’ve worked, but six inch posts will look better.

My dad helped me move and set up my Procut Mobile Sawmill. I hadn’t used it for several months. I did use the saw (a Husqvarna 3120XP) for cutting down several beech trees at a friend’s place. We’ll be skidding out the logs from those trees in the next few weeks if it dries up a bit. Those will be milled into beams and lumber for the porch, at least that’s the plan.

Milling the porch posts went well. It’s not a speedy process with my chainsaw mill, but I wasn’t out to set any records anyway. Things proceeded well, though. We cut 15 posts after getting the mill and everything ready. We also had to change chains on the saw after the first one broke. I have three chains, but they’re all about worn out, having been sharpened about as much as is desirable.




As you can see in the photo of completed posts, some still have bark and rounded corners. I’ve judged this to be fine. I’ll shave the bark off, and the rounded corners will work and look fine. On some of the posts, the rounded corners occur on the end which will be cut off when the posts are cut to length. We also cut a few 2x4s from some logs that weren’t quite large enough to make 6x6s.

With good weather in the coming weeks, we’ll get the rest of the posts milled. We’ll also have to haul beech logs home and mill them into the desired sizes. That may be before or after work on the root cellar and porch foundation work.

(A special thanks to my dad for providing the photos for this post.)

Plaster samples

Two weeks ago, my dad and I worked on some gardening tasks. We had nice weather and the ground dried enough for it to be worked. Gardening tasks are important, and it’s that time of year. My dad has agreed to do a lot of the gardening work in order to free my time for working on the house.

Right now getting the root cellar floor poured and the blocks laid for the walls is what’s standing in the way of significant visual progress on the house. As I’ve been down in the root cellar hole shoveling out dirt that’s washed back in with the rain, I’ve wished greatly that I would’ve been able to have done the concrete and block work last summer. It would’ve saved time right now. I cleaned out about half the washed in dirt a few weeks ago, but you wouldn’t know it now. It actually seems like it’s worse than it was before. I shoveled out a bit last week, but it was frustrating because it was wet and kept sticking to my shovel.

However, as it stuck to my shovel and I complained to no one in particular, it occurred to me that this might actually be a good thing. Why is this dirt sticking so badly? That is one of the properties of clay – it’s sticky. As I continued to grow in height while working in the hole (I had a couple inches of the mucky goo stuck to the bottom of my boots), I became more excited about the possibility that I might be mucking around in the plaster for my straw bale walls.

With this in mind, I collected two samples: one from the bottom of the root cellar hole and another from a pile near the cellar that was excavated from it last spring. I put these samples in jars, added water (and a little salt), shook them vigorously, and left the contents to settle. With this process the larger aggregates and sand settle first, then the silt, and finally the clay (adding salt can help speed up the settling of the clay which can take a long time). Once everything settles, you can determine the relative percentages of the different materials in the soil.

It seems like there is a lot of clay in my samples, so much, in fact, that I cannot clearly determine the lines of demarcation between the different strata. When working with the dirt in my hands, there are clearly some small rocks (aggregate) mixed in, but nothing too bad.

The next thing to do was to try making some sample batches of plaster with this dirt. I brought some up the hill along with a hay bale from the barn. I cut the bale in half with my chainsaw so that I would have twice the surface area to try out my samples of plaster on. Then, I mixed two batches of plaster using dirt from the pile near the cellar.

For the first batch, I mixed on part dirt, one part washed masonry sand, and one part chopped straw (not pressed into the measure, just loose). I plastered a section of the side of the first half bale with this mix. Then, I mixed the second sample using on part dirt, two parts sand, and one part chopped straw. My younguns helped me put this plaster on another part of the same surface as the first plaster.

The plaster actually felt good, and we enjoyed putting it on the bale. The second batch felt a bit sandier, of course. Both went on nicely. They’re not dry yet, though. So, I haven’t determined for sure their suitability for the walls in the house.

The weather’s a bit cool, so it’ll take a little while for them to dry completely. At that point, I’ll see how well the samples adhered to the bales and check them for other desirable qualities. In the following photos, you can see the texture of the samples and the chopped straw in the plaster. The one on the left is the first batch (one-to-one mix) and the one on the right is the second batch (one-to-two dirt/clay ratio).

It will be really neat if we are able to plaster our walls with dirt harvested from our building site. Previously, I figured that I would buy bags of pottery clay for the walls. This new possible method will save some money and will just be better in many other ways. Even so, in order to get the desired wall color inside our home, the final coat on the walls will probably use kaolin clay bought from the pottery supply store.