A word about Cement

One thing I noticed doing masonry and learning about foundations was just how ubiquitous the use of cement and concrete is. The mortar used between the stones contains cement. The concrete we pour between the stones and the insulation of the knee wall contains cement. The foundation of nearly every building is made with concrete, and therefore cement. 

Just to clarify, cement is burnt lime mixed with clay, silica, iron oxide, and aluminum oxide. When mixed with water, cement will set and harden. It is the binding ingredient in concrete, which is cement mixed with an aggregate for a stronger hold. Sand and gravel are the most common aggregates. 

Concrete is a staple in modern construction of basically any structure. Bridges, buildings, side walks, and road ways, for example, all use this material. We can shape it into distinctive and specialized forms, and use it to support massive loads (with the right reinforcement). It's durability and resistance to weather also make it a very popular building material.  Despite these advantages, I think it's important to know the price we pay to use this material.

Manufacturing concrete is extremely energy intensive. The limestone used to make it mostly comes from mines. This involves heavy use of fossil fueled equipment as well as the explosives. The limestone must then be transported to a factory, at which large grinders and crushers break the stone into smaller chunks. This process takes several stages to get the stone to the right size. The stone is then mixed with other ingredients, including iron ore, and passed through huge kilns that heat it to about 2,700 degrees Fahrenheit. The remaining material (a lot of gases burn off in the kiln) is cooled and then ground into extremely fine powder and mixed with more limestone and gypsum. This material is then packaged and sold as cement. 

There is an environmental cost as well. Often, limestone deposits occur around karst, a topographical formation that is caused by dissolving limestone, which forms underground sink holes and caves. Ground water often flows through these formations, and when mining operations happen at these sites the flow of ground water is disrupted. Mining crews sometimes remove the ground water to gain access to the mining site, and this lowers the water table. Removing the rock and water from a limestone also removes the under ground support for the rock and dirt on the surface. This can cause sinkholes. These can be dangerous for mining crews and people living in the surrounding area.

Cement is also extremely alkaline. It burns when it touches your skin, and you have to rinse your hands in vinegar to neutralize it. You don't want to breathe it in either. The particles are so fine, they could easily coat your lungs and I'm sure that damage would be hard to reverse. 

Right now, concrete is too essential to our building industry to replace. There are few materials as versatile and easy to work with. But I hope that we can work towards finding alternatives, or alternative ways to process the cement. The cost in terms of fossil fuels is very high, and the water supply is definitely not something we should be jeopardizing. 

http://education.seattlepi.com/environmental-hazards-limestone-mining-5608.html

http://www.cement.org/cement-concrete-basics/how-cement-is-made

Drawings and Plans

I just realized that I never posted any other drawings besides the detail of the knee wall. I did a few of the elevations myself, and Mark has a really great plan drawing that gives a sense of the interior space.

The entrance is on the North side, at the top. There will be a small mud room that leads into a hallway. There will be a closet on the left and an office space on the right. (Directions are reversed when looking at this picture.) The bathroom and the bed room are down the hallway to the left, and the kitchen and living room occupy the open space on the south side of the house. 

One thing I love about the design is the large picture window on the south side that looks out onto the property. Mark has plans for a garden and a deck, which will make the view even more picturesque. I also really like the openness of the living room and kitchen areas. This will be good for heat circulation in the winter, when the masonry heater is going. 

There have been several changes to the plan since this drawing was made. There will not be a window on the west side of the living room. That's where the masonry heater will go, and it is better to have some good solid insulated wall behind it. There will already be a significant thermal break because of the large picture window. Mark also decided that the sliding door that is drawn in the bedroom will just be a window, and that there will be another on the north wall.

Some decisions have yet to be made. I know Mark was thinking about using partial barriers and partitions for the office space. Perhaps a half wall, or a glass wall. That way it would not be entirely closed off from the rest of the house. There is a lot of time to think about that still. 

Here are some of the elevations that I drew. Hopefully they convey a sense of what the house will eventually look like. 

South Elevation

West Elevation

The roof is pitched pretty high. It will give Mark a lot of expansion space and the possibility of another finished room. Here is a cross section of the roof structure. 

June Update

It has been a while since my last update, and, not surprisingly, there has been a lot of progress! I did not work a lot in May due to finals and the general craziness of the end of the year. But my official internship started June 1st, and I am now in my third week of working full time on the building site. I'm still astonished by how much we have been able to accomplish. In just the first week, Mark and I finished erecting the posts. We have nearly completed the knee wall (against which the stone wall rests), finished installing the flashing, and we have laid a significant amount of stone.

Here is a picture from June 4th. The posts themselves are somewhat obscured by the bracing, the non-vertical beams that make those tipi-like shapes. The site, which is on a hill, is pretty exposed and the wind can be very strong. All the posts have bracing that secures it in all directions, just to be sure that the frame won't blow over. The bracing will probably stay there for quite a while, but will come off when the frame is completely finished, there is a substantial roof, and or we need to start putting in bales of hay.

The whole bracing ordeal struck me as funny because even though the bracing is not a permanent part of the structure, it took so much longer to install compared to the posts themselves. The 2x4s that reach to the ground are anchored with stakes, and to bury those stakes we had to dig holes that were about 2.5 feet deep. This doesn't sound like much, but this site is located on a kame formation, which is a mound formed in conjunction with a kettle, or basin formation. These formations are the result of glaciers melting and depositing the sediment they carry. Pine Lake is actually the kettle to the kame on which we are building. The mounds are generally made of gravel and rocks of varying size, whatever the glacier happened to be carrying and happened to deposit. These mounds have several advantages when it comes to building. Aesthetically it is very appealing to be situated on a hill. There is also great drainage due to the large amount of gravel, so flooding will not be an issue. However, digging in this kind of soil is... difficult to say the least. The most useful tool is called a "Delaware County shovel," and it is a 30 pound solid steel bar used to loosen up the stones so that you can scoop them out. Real shovels are not really much help.

Here's a picture of the kames. They make for really pretty rolling hills. Mark's house is situated on the highest hill, behind where the picture is taken.

After all the posts were up and braced, Mark started on the knee wall. The purpose of the knee wall is to provide backing and support for the stone portion of the wall. It will also partially support the straw bales when they are installed. Between the frame of the knee wall and the stone work there is a layer of R15 extruded polystyrene insulation. Here's a picture that shows all three components.

The stone work has consumed most of our time on the site this past month. It takes a remarkably long time to find and fit the stones together because there is a lot to consider. For a wall like this, that is not slip-form, you have to pay attention to the joints between the stones, the level of the row as a whole, the depth of the stone (whether or not it will run into the rebar). You also don't want the shapes to be too regular lest it be too brick like, so variation in size and shape is good. While you fit them, you also have to leave room for the mortar, which adds between half and inch and an inch to the level of the stone. The most basic rule, however, is that you want to lay one stone on top of two stones. This makes the wall far more stable, as long joints that run up the length of the wall are vulnerable. Sometimes a long joint is unavoidable, however, due to a large rock that reaches up a few levels. But in cases like that it's generally ok.

Here are some pictures of rocks that I fit. You can see that the larger rocks will have large seams on either side, but for the sake of some variation it is ok.

Sometimes, you have to cut the stone to make it fit better in one way or another. Maybe you have to cut a protruding bit off, or angle the face of the rock so that it is more vertical (that is called rocking the face). Sometimes you have to cut the rock in half entirely. This is generally not advisable because it takes a long time with a chisel and hammer and it's usually better to just find a stone that actually fits the spot. But if the fit is otherwise absolutely perfect it is justifiable. This was my first successful major cut, and I'm proud to say, the stone fit perfectly afterwards. :)

The downside to doing this kind of work is that the weather dictates what you can do to a great extent. The mortar, in which we lay the stone, and concrete, which we stuff behind the stone work against the insulation, need to cure and set and are very delicate for a few hours. If it looks like it will be a rainy day it is better to not even try to lay stone. Even on good days, we cover the work we have done to protect it from potential showers during the night. We've had some intense storms in the past few weeks. I caught some nice clouds right before a storm broke last week.

For the coming weeks, we will be focusing on installing the rim joists, which will tie the posts together so that the whole structure can support the roof. We have started on the North wall. Each wall will get a double layer of 2x12s. But since there is not one piece of wood that can span the whole distance, we have to stagger the endings of the 2x12s so that both pieces don't end on the same post. Some of the posts, the solid 6x6s, have a lip cut into them to hold both pieces of wood. But the other posts are 2x6s' nailed together and do not have a lip to keep the rim joist in place. So, we nailed a brace to the backs of these posts, which gives the joists something to rest against.

We will also continue to lay stone. That project will probably continue all summer. But, as we determined yesterday, we are about 3/8ths of the way done with the entire house, and we are nearing the end of third week in June. Perhaps we can finish by the end of the summer. Weather permitting. 

Sill Plates

Last week we installed the sill plates, which are the base for the frame that will support the roof. The straw bales themselves are not weight bearing in this particular structure, although there are straw bale buildings where the bales are the structural support as well as the insulation. I am sure that it can be done, however there is the worry of compression. That is why Mark is building a frame, and why we install the sill plates.

Here is a drawing of the whole set up.

A cross-section of the foundation and wall structure.
Drawing by Mark Rogers

The sill plates are kind of hard to see. They are represented by the rectangle with an "x" that is connected to the j-bolts, which are the smaller, j-shaped hardware that stick into the foundation. As you can see from the drawing, the sill plates and the frame will be closer to the inside of the thick walls, supporting the roof with a post and beam system. The insulation will go between the stone wall and the frame of the house. The straw bales, when we get to that stage of the construction, will have to be cut out to fit around the beams. 

Instal ling the sill plates was challenging, but there is a trick. I hope Mark won't mind me sharing it. :)

Sill Plate installation

The first step was to measure 19 inches in from each edge of the foundation and mark that with a chalk line. This is about the thickness of the wall, though it may extend farther into the interior space when the plaster is applied. You can see the blue chalk line a little bit in this picture. The j-bolts were installed already, when the foundation was poured. The challenge, then, is to drill the holes exactly where they need to be in order for the plate to sit right along the edge of the blue line, since the bolts are not placed at exact, regular intervals. 

The next step is to set the plate parallel to the blue line, behind the j-bolts, by measuring and equal distance on both ends. This will ensure that the following measurements are accurate. Then, using a rafter square... 

Rafter Square
from www.irwin.com

we drew two lines, one on either side of the bolt (which you can see in the photo). The lip of the square would go on the far edge of the sill plate and keep the line square. The bolt would go in the middle, between these two lines.

The next measurement is from the blue line to the middle of the j-bolt. Then we measured that same distance from the bottom edge of the sill plate to determine where to drill the hole. There was always a bit of anticipation after drilling the holes and checking to see if the plate will fit over the bolts. Mark let me install 3 plates by myself, and I got pretty good at it by the end, if I do say so myself. Its a shame they are all finished now!

The last step is to put a layer of tar paper on the underside of the sill plate. Wood and masonry (concrete) are generally not supposed to touch, so it just adds a layer of protection. You can see a little bit of it sticking out at the corner in this picture. It doesn't have to be exact since it won't be seen. 

The sill plates I installed. All by myself!

The next step in the process will be to add foam insulation to the outer vertical edge of the foundation. This will ensure that the insulated envelope around the whole house will be complete and there will be no heat leaks. Then, we will install flashing to protect the foam from wheel barrows.

That's all for now! 

Laying the Foundations

This spring, I am very fortunate to have the opportunity to work with a natural builder on his very own straw bale house. Mark Rogers is one of a few builders in the area, with experience in stone masonry as well as straw bale construction, and he has graciously allowed me to tag along and "help" (learn) from him through the process.

I met Mark towards the end of last summer (2014), when he was in the process of pouring the concrete foundation for his small house. It is about 1000 sq ft, not counting a second story loft, and the floating slab foundation serves as the floor of the interior space. Here is a quick diagram of a basic floating slab foundation, though there are several variations. 

Image from:
http://www.barntoolbox.com/foundation-types.htm

Mark's foundation is a little different. There is not only rebar in the thicker portions that will support the walls, but there is also welded wire reinforcement throughout the slab. The concrete is also completely insulated with 5 inches of foam insulation underneath. This way, he can take advantage of the foundation/floor's thermal mass. He has also put in a radiant floor heating system, which will run hot water through small pipes embedded in the concrete and heat the floor. That will be super cozy and nice during the winter. Here are some pictures of the form before the concrete was poured. 

Another thing that is different about Mark's foundation is that there are a few dozen pieces of rebar sticking up about 3 feet high all around the edge of the slab. This is a picture of the slab covered for the winter. Mark used straw and foam insulation underneath a sheet of plastic to help protect the concrete from thermal stress and the elements. You can see here the rebar I was talking about. These rebar posts are anchored into the concrete slab and will serve to anchor the stone wall that will lie underneath the straw bales. 

There are a few advantages to having a stone wall. Not only will it be very beautiful when completed, but the stone wall will raise the straw bale up from the ground and protect it from water damage. Plaster often gets worn away by the splash of rain water falling off the eaves of the roof. It seems minor, but years of splash can really damage the plaster and straw bale. 

Hopefully I will figure out a way to scan and upload some of the technical drawings to illustrate the plan for the next stages of construction. I'll keep you posted!