Some considerations about domed and vaulted roofs

Each space in the house has an independent roof. So it is starting to look like if several domes, vaults, or combination of both, are placed against each other (picture at the bottom). Until now there is a reciprocal roof over the living room and 3 domed or vaulted roofs (or a mix of both).  One vault is over the entrance corridor and two domes cover each a room. The one I am making now is the dome over my room, which is quite irregular in form so as a consequence the dome is also irregular, you can see some info about it in the previous post here: Domed roof over an irregular shape.  The roof over the living room is a 12 beam wooden reciprocal roof, but I will probably replace it by a big dome.The reason is because I did it before I learned about domed roofs and how beautiful they were. Here are some pictures, from a facebook photo album, about the reciprocal roof: Reciprocal roof. The pictures document a bit what I was doing.

The domes have no supporting poles, they lie over thick (60 cm wide) walls. All the domes are also lying against each other in several sides (the internal walls of the house), that eliminates the horizontal forces there. In any case the walls are thick and rounded (the house is basically an hexagon), and the thickness of the domes so thin in comparison to the supporting walls, that there is no issue with horizontal forces pushing the walls. The thickness of the domed or vaulted roofs  is 10 cm corresponding by the width of the brick, plus more or less 3 cm stucco over that, so a total of 13 cm (which I just noticed that it is not a lucky number!). For the living room, the biggest space, the thickness for the bricks of the dome I plan to make, replacing the reciprocal roof, will probably be 15 to 20 cm in the lower part of the roof and 10cm in the higher part. But that could change because maybe I will stabilize the bricks with lime or fire them to make them harder without needing to make them thicker. I add to that the 3 cm of stucco.

The stucco to make the domes (or vaults or combination of both) water resistant is something similar to Tadelakt, that is lime with vegetable soap, like olive oil soap or coconut soap or soya based soap etc…. rubbed hard with a smooth river stone or steel trowel, except that in the inner part I also add clay. Lime is mostly pure with no clay in the exterior part of the stucco. Lime reacts with the soap and makes it hydrophobic, water resistant, but still breathable. Still a lot to work so I hope it will all workout OK :).

Roofing has been a challenge but very gratifying and where I have learned and enjoyed most. Those flat domes are a pleasure to work with. If you used unfired bricks 20x10x5 cm the domes and vaults should not have more than 8 meters wide, if they are fired bricks it could go up to 10, beyond that I should start using thicker bricks at least in the lower parts of the domes or stabilise them by compression and/or with lime.

Several options…. Seems complicated but less as I gain experience. Testing is important. I started with very small spaces and got each time bigger, to build confidence and experience. At the end it gets simpler and simpler and it is very pleasant to work with. I still consider myself a rookie and have had bad experiences on the way, but then again, those made me want to work harder to get it right, and it seems to be working.

 

Best wishes !

jrv

 

PD: This is an old picture when there were only 2 domes, there is now a 3rd and bigger dome on the back.  They are also without plastering in the picture (not anymore). It gives an idea of how the domes lie besides each other as well as how the final result will be when all the spaces will be covered: 12140083_10153349286778401_2409549385569915495_o

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Domed roof over an irregular shape

The following pictures give an idea of the construction process of the domed roof of my room. It is made with the technique explained before in the post: “Dome made with unfired earth bricks”. The difference here is that the roof is over an irregular shape and partly lies over another smaller dome. The shape is easier to understand by looking at the following pictures and the explanations.

Here below you can see me over the roof, it gives an idea of the proportions. You can also see that four curved sides are coming together.DSC_6782

The picture below shows the location of the room in relation to the house. The room is in a rounded corner of the house, its ground level is one meter over the the outside level. That elevates the house and isolates it from the ground humidity. All the sandbags that form the lower part of the outside wall will be removed and stuccoed in its due time.DSC_6768_m

The following three pictures show how the bricks are placed. Only mud is used. The bricks form an arch, the mud to place the bricks is rather liquid, the bricks have a certain proportion and are dry when placed. If not all the conditions above are met the brick or roof (if arches are not formed) could fall.DSC_6764_m

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Below you can see that the left side of the roof lies over a dome. A dome that will probably be a bathroom. I am standing more than a meter above the ground level of the room while a place the bricks.DSC_6757_m

Here you can see how the roof sides are “advancing” and closing themselves.DSC_6749_m

I stand over some pieces of wood in order to have enough altitude to place the bricks. Some steel rods were temporarily placed over the dome in order to give an idea of the direction of the roof. They confused and annoyed me more than helped so I took them out, they are not necessary.DSC_6748_m

My head can be seen popping out. As you can see the left side of the roof is not a straight line, it curves to the inside so the dome obtained has an interesting form.
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Here are the bricks used. The dimension in centimeters is 20x10x5. They are made of earth, with mud. An earth that I estimate has around 30 % of clay.
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Here you can see how the sides of the roof are coming together in order to close themselves. It is interesting to see the bricks forming arches everywhere, strategically integrated, to make a roof. It shows that basically any form can be closed using that technique. Note that each side is formed by arches and the superposition of all sides forms the dome. You can also here see that the right side is curved to the outside. It is clear in this picture how one side of the roof lies over a smaller dome.
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Here again you can see how several arches are forming the roof.
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It is now time to say goodbye, here below I wave you (so you can easily spot me) my best wishes !DSC_6774

 

 

 

Dorodango

 

 

 

Here below is the first Dorodango that I made basically using the instructions defined in the following link: http://www.kyokyo-u.ac.jp/youkyou/4/english4.htm

It is a Japanese technique that uses only with common earth and water. I find it pleasant to do and it lets me understand much better the properties of earth. That knowledge comes very handy when you are making a mud house with cheap and easily accessible materials (just dig a hole to get them).

Making it is fast and fun and lets you understand stucco techniques better. The surface is cold, very soft, and shiny. It can be used to make a pretty and classy surface (wall or ground), made with the most common material on earth: earth.

It can easily be made water proof or at least quite water resistant. That comes handy if you want to use the technique for a wall in a bathroom or in the exterior.

Its very pleasant to do, I recommend it to anyone, you just need earth, a bit of water and preferably a dry day. Kids love to do it too and you end up with a pretty piece of decoration at the end.

It is funny to remark that all the people I have showed it too and ask what they thought it was responded something else than mud, they most think it is some kind of metal, or stone, or marble.

Best wishes for all !

Photo on 4-12-16 at 09.26
dorodango

Dome made with unfired earth bricks

The first post explained, in general terms, how the house was being built. I will now talk more specifically about the dome that I am building over my sons’ room. My son Pablo Mateo is the one in the following picture. He was born in 2006. He likes to pass time in the building site and often helps. He is sitting there in the roof, in a thick wall (60 cm wide) that divides the entrance corridor on the right and his room on the left. The wall is thick and can easily support the weight of both domes. The thickness of the roof is a fraction of that from the wall. Therefore the roof is, in relative terms, light and can be supported by the wall. Where my son sits water accumulates so something like a water gutter was made later on (not shown in the picture) in the middle to drive the water out. After the gutter was made both domes were covered with a 3-4 cm width layer coating of waterproof cement. Before cement was used it was necessary to cover the roof with plastic to protect it from the rain, that is what you see behind my son.

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My son also likes practicing Kung Fu. The following picture is not related with building techniques, but I am so proud of it that I published it here :). He is practicing in our “garden”. That place is next to our property, next to the building site. It is where we currently rent and live while the house in being built.

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In order to make the dome you start by laying arches on each corner of the room.  A dome or a vault can be seen as the addition or superimposition of several arches, which by themselves are structurally a strong form. You add a little mud on a dry brick and place it over the previous arch by making sure that you form a new arch. You can place it slightly higher or lower in relation to the previous arch in order to control the curvature of the roof. The following pictures give an idea of how it is done.

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As shown next, you can make mud by using earth from your own ground. To gain garden space, I take it from the wall where my smallest son, Miro, is sitting. You could also take it by digging a whole on the ground. If you dig a one meter deep whole I think that chances are high that you will find quite good earth for that purpose. To make a strong “plaster” mix it well until nothing is left dry and a kind of a thick mud soup is formed. Once done and when it is quite liquid, but not too liquid, you can place it in a bucket and use it to place the bricks.

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Before placing the bricks my son Pablo Mateo some times works on them to let them more uniform. It is not always necessary, but he likes to keep busy. He is a great company and helps to have a good time in what can otherwise be a lonely job. What helps a lot too to make the job nice is to hear to music while working.

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The process is not too hard and with practice it becomes natural and can be improved relatively fast. You just need to make sure that you always keep forming arches. You place bricks as shown in the pictures that follows. The two corners will eventually merge and you keep on going until all corners come together. When each arch is closed you work on the final brick in order that it fits well in the middle and the arch is secured.

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As I explained before these are the conditions that need to be satisfied to make the dome:

  1. The bricks dimensions are more or less 20x10x5 cm. Bricks are not too small nor big, not heavy and relatively flat. The area used to “glue” them is big in relation with their width.
  2. Each time an arch is formed which lies over the previous arch. If the arched shape is lost the roof can become unstable and fall.
  3. Little mud is used to glue the bricks. They must be glued dry, like that they stick. If the bricks are wet or too much mud is used they can fall.
  4. Each corner starts with a 45 degree angle with respect to the horizontal plane. Like that every brick in the roof is under compression. If the angle is bigger the roof could have parts that are not under compression and could break.

In the following picture you can see how the different beginning points of the roof, starting from each corner, are united. I used a mask to protect myself from the dust because I had a bad cough those days. Probably caused by some allergy.

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The room is more or less a triangle therefore the other side of the room starts on only one corner, laying the first arches of the roof against the wall. That pointed part of the room has a window that connects to the living room.

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Since the room has three corners once the roof corners starting from them come together they form a triangle. If they had four corners they would have formed a square like the one you see in the other dome in one of the following pictures taken from outside. From inside the roof looks like this:

11116217_10153349285463401_2517307646515871329_o From outside, near that building stage, it looks more or less like the following picture. I closed a bit the triangle on the corners. On the right side you can already see a bit of cement over the domes. Each dome generates a force against the wall but since they are placed one against the other and the walls are thick the horizontal forces are partially eliminated and relatively weak. That leaves mostly vertical forces over the supporting walls.

In the front part of the next picture you can see the start of yet another dome. That one will cover a bigger surface over an irregularly shaped room. Therefore I left if for later and made the domes over the smaller and more regular spaces first. Like that I have time to acquire skills starting with the simpler rooms.

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From outside you can see how the domes look as well as the entrance of the house. I am over the roof placing the water proof cement layer in order to protect against the rain. The cement will be painted in order to make it look nice. I will probably use a cement based paint. The paint will be a mixture of white cement, calc, salt and iron oxide to give it the colour. It is a cheap paint, looks nice and lasts for years.

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It is not too hard to imagine how the end roof will look like. Basically each room will have its independent dome or vault or a mixture of both over it. It will be like if several differently shaped domes come together one against the other. That gives them structural strength since like that the forces tend to push the walls down and not to the sides. It is important to see what to do with the rain water. It could be redirected outside or inside and collected in order to re use it. In the picture above you can see a little bit that in between the two domes, or between the two arches, there is something equivalent to a gutter that redirects  the water outside.

The construction is paused while I am now in Sao Paulo visiting my oldest son Martin. He was born in 1993. Here we are both in his apartment, resting and being together. I hope I con convince him to drop the city life and come live with us, like that we can build something nice 😉 and explore the Chapada Diamantina !

martoSP

I am sure that he would like to explore some of the places near where I live, like the Vale do Pati in the picture below. That probably beats sitting behind a computer 😉

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Best wishes !

Jrv

A General Explanation of my House Construction

Hello all! This is the first post on this blog. The goal is to document the process of building my house. Most of the pictures from this post were taken from my facebook account. I made a couple of albums to show it to my friends. In case that you are interested in seeing more pictures and the associated comments you can take a look at the public album called my super adobe fortress. I also made an album to document the reciprocal roof construction that I made to cover the living room.

A few videos were posted on youtube, they give an idea of how the house started :

I have taken very few pictures and documented little about the building process. Probably because I pass most of my time having fun doing it or reading about things I need to learn. Documenting is time consuming and not as much fun, so I gave it little priority. Nonetheless now that I have a little bit of time I think it is worth while talking a bit about it and showing it to the rest of the world.

Most of the pictures were taken by my wife. Without her support and good will I would have not been able to do any of this. She fed me and patiently took care of our kids while I was on the building site.

To have an idea about how all of this looks like lets go straight to the point by showing a first picture of me working, back in the beginning of the year:

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I live in the Chapada diamantina, in Bahia, Brazil. On the border of a national park, very near a colonial city that was built and grew out of diamond seekers. The house was made over the ground of a diamond open pit mine. That sounds complicated but the bottom line is that it was just basically a big hole that men dug in order to find diamonds. Since the ground was in such a condition I could buy it cheap. I knew the place well because it was owned by a friend who lived there and that I visited often. That gave me the time to feel the place and visit it during a whole year before deciding to buy it. Nobody seemed to like a place with a big whole in the middle and surrounded by hills. It did not bother me, the price was right and I was buying it to a friend who would become my neighbour.

So I bought it and I rented a place next to it to be close to the construction. I begun the house by preparing the foundations and filling part of the mining whole. I digged a trench and filled it with river stones to support the future walls. I used the earth from the borders of the ground to make mud and fill bags. Like that I did not have to transport cement from outside and I could get all the material I needed from the same place. I used earth from the surrounding hills. The walls of the house were being built while I was landscaping: flattening the place and gaining space for the garden.

The house is made of polypropylene bags filled with adobe. That is in other words bags filled with mud. The bags were bought used, at the local bakeries, little by little, as I needed them. Originally the bags were used to store wheat to make bread. Once the mud inside the bags dries they get hard and form gigantic bricks weighting around 70 Kgs. Some call them super adobe bricks. Once they dry you can cut the bag out and plaster it with the same mud or other type of plasters that you may prefer, even cement. I personally do not want to use cement as a plaster because what I like about mud is that it stabilises the humidity and temperature inside of the house. It is deliciously fresh inside, even when it is very hot outside. And when its cold it stays quite warm inside. The same happens with the humidity levels. No mater how dry or humid it is outside, inside it stays at basically in the same humidity range. That is the magic of earth ! Besides that it has other characteristics as being bullet proof, sound proof and very very durable. It lasts long and is not affected by the environment because it is by itself the environment and integrates with it perfectly. The interior of mud bricks is very dry, making it impossible for insects to live or damage them and perfectly preserving wood inside of.

The mud is made from earth taken on site. The amount of clay found on the local earth generates good super adobe bricks that stay hard when wet and are strong under compression. Below you can see me making the mud. It is done by hand, a very good exercise. That is the other reason I decided to build the house: exercise. I was not feeling good by passing too much time reading in front of a computer, I needed to do something physical. I reasoned that better than going to a gym or to do some sport I could spend my energy by doing exercise and at the same time obtaining a liveable house as a result.

Anyways, back to the mud… : it is important to mix it well, like that when it dries it stays quite hard:

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Between each row of super adobe bricks two rows of barbed wire are placed. This gives some tensile strength to the construction and avoids the wet bags to slip but I still have my doubts if they are really necessary.

The foundations where the walls are placed are more or less 60 cm deep and filled with stones taken from a nearby river. Besides that the first row of bags is also filled with stones. The initial rows of bags with mud therefore lies over stones. The ground level outside is a bit below the first row of bags filled with stones. Like that if water reaches the bottom of the outside walls it is not much of a problem. In any case I deviated the water flows so that even in case of heavy rains as little water os possible gets close to the house.

After a certain level I started using big adobe bricks to continue, that is because the higher I went the hardest it was to fill the bags and it was easier instead to place bricks. You can see how they look like on the right side of the first picture above.

To avoid using cement or wood the doors and windows were made with arches. Several of them are also shown in the first picture just mentioned. Here next is a picture of one of my first arches. Note that the adobe bags over the arches are also forming by themselves another arch, a very exotic type of arch:

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You can see that the bag used to make the superadobe “brick” is no longer there. That is because once that the mud dries the brick is hard and the bag can be taken out and plaster can be used in between the jointures of the “bricks”. What remains is the form of the bag. After a bit of stucco with the same mud a white paint made of light coloured clay earth, found on site, was used to paint the bricks. Finally, above that it can also be painted with some type of natural oil to give it a nice finish.

Originally I wanted to make a green roof, that is  a roof covered with earth and some vegetation. In order to do that I made a reciprocal roof covering the living room:

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From inside it looks more or less like the pictures below. It is not yet with stucco so do not get disappointed because at the end it should look much better:

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The basic structure of the reciprocal roof over the living room looks more or less like this from outside:

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The house until now has 6 spaces, lets call them rooms, each room can have its independent roof. That gave me the opportunity to think about what kind of roof I could put over each space. I practiced making domes starting with the smaller rooms. Like that I could learn more roof techniques. I liked quite much the reciprocal roof but I loved the vaulted and domed roofs so I started learning by building them, initially starting by covering the smaller spaces and deepening the learning by making the roofs over the bigger rooms. Here are the first roofs I made using the Mexican vault technique:

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The material for the bricks for the vaulted roof are obtained and made on site, the dimensions are important, if they are too big they get heavy and can fall while being placed. If they are too small it takes too long to build the roof. The weather is usually hot so they can be made and are ready to be used fast. In the picture below the earth used to make the bricks is taken from the left side “hill”, like that garden space is gained around the house:

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If I get handy enough on building earth domes I will probably replace the reciprocal roof over the living room by a domed one. It will be similar to the ones shown above but much bigger and with a rounder base. The technique to build those kind of roofs is well explained in youtube in videos such as this one: Mexican vault.

My first vault using something similar to that technique is for the entrance corridor. Below is the house entrance from inside, it has a view into the living room at the end. On the left there is a window to one one room and on the right a door to another. It lies over four arches. I left an opening in the middle in order to get light. More light enters through roof openings than through windows or doors.

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Once you cross that corridor you reach the bigger space, the living room. It gives access to two more room. It has interior as well as exterior window openings. There is also an opening in the middle of the roof a chimney and a sofa made of adobe. It looks basically like this:

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Above you can see one of my sons, he comes often to help. My other smaller sons here below also come often to play with the mud:

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This panoramic picture of the living room shows the future chimney and how the first arches I built, they were much thinner than the ones I made later. You can also see a sofa also originally made of mud:

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As I got more experienced I started making bigger arches with different brick forms, even double arches. I made them bigger in order to support the roof and also because I found them beautiful. The entrance to the house has a one of those doubles arches. My son is sitting on it:

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Next below is a view from outside. The picture is old, the walls are much higher now but it gives and idea of how the super adobe walls were made, as well as showing the structure of the reciprocal roof (in the back, right):

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Before I knew about Mexican domes I learned about african domes. The picture below shows me working on my first dome, more of the african type, it was done using the Nubian dome technique. Nubia is in the south of Egypt, they developed, more than 3000 years ago, a technique to make vaults. I practiced with the Nubian technique in a room that could become a bathroom or a sauna:

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It was an interesting experience doing it but it was hard work because of the big dimension of the bricks. I therefore investigated more into vaulted roofs and found out about the Mexican vaulted roofs. A refined technique with lighter bricks and a much flatter type of dome, I loved how it looked like. It was easy to decide that it would be the next choice to make the other roofs. The one below is the second space I covered using the Mexican technique (the first was for the corridor, just next to this one, on the right).

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Each corner is used to start the roof, either by laying over the corner as shown above or lying against the wall as shown below:

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Once the arches advance by piling one over the other, they merge together as the roof gets closed. The great thing about this technique is that no support form is needed to make the roof. These Mexican vaults are much lighter roofs and faster to build than the ones using the older Nubian vault technique. Note that Mexicain vaults are not really vaults, they are domes, I do not know why the wrong name is used to describe them. In any case both vaults or domes are made by the union of arches. Mexicain vaults come from Nubian vaults. Those techniques were invented in Africa, on dry places who had no trees, it was natural to invent something that would only use earth and water to cover spaces. They had no other options. The following conditions should be satisfied to build Mexicain vaults:

  1. The bricks dimensions are more or less 20x10x5 cm (instead of 20x20x5 cm in he Nubian case). Bricks are not too small nor big and the area used to glue them is big in relation with their width.
  2. Arches are formed that lie over the previous arch. If the arched shape is lost the roof can become unstable and fall.
  3. Little mud is used to glue the bricks. They must be glued dry, like that they stick. If the bricks are wet or too much mud is used they can fall.
  4. Each corner starts with a 45 degree angle with respect to the horizontal plane. That is important like that every brick in the roof is under compression. If the angle is bigger the roof could have parts that are not under compression and could break.

If all those conditions are satisfied the roof will not fall :). Finally cement made with water proof additives covers the roof so that no water damages it. Cement over the roof is not a problem, the house will still have a big place to breathe through the walls.

Here below I keep on working on that same roof. It is by now finished. I will maybe show pictures of how it looks later.

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I hope I will write more about the rest of the house. This was meant as a first post to get you fast acquainted with what I am doing. Do not hesitate to leave comments and share your experiences ! Building with this basic techniques has been enormously rewarding.

Ahh and if you are interested to come and help me you are very welcome, just let me know to see how we can arrange it I have a lot of space and like to teach, but be aware that the work is hard !

No, joking aside, it is not hard, it is healthy and will provide you with the knowledge and a set of tools which will make you very happy and independent.

Best wishes !

Jrv