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

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