Project 2302 - Threza - Design of triple roof

Far away in a valley in Portugal lived a family among the cork trees.

They lived in an earth-bag house. They wanted a roof much larger than the house itself to create large shaded areas, and the possibility to add rooms left or right to the house.

A team of construction workers was hired and started on the project..

A circle of posts was places on an offset to the building and a large roof was being built on top of it..

Then the problems started: the framing design was incorrect: an A-frame style on the oval outer ring, a row of wooden A's, increasing in size, the first smaller frames worked well but as the larger frames were being built, large tension forces on the center beams started to grow.

The center beams started making noises.

Wood is for compression strength, not tension.

Also the roof was divided into sections for the roof tiles that didn't make sense. Adding tiles would make the frame crumble (let alone the winter winds which sweep the Iberian peninsula).

The workers somehow wanted to add steel beams from the ground to the structure to create vertical support (also they 'needed' to purchase a welding machine for this purpose).

The owners wanted a reinforced concrete ring on top of the building and the workers were building a brick ring..

The one thing that an earthbag wall can do is vertical support. It needs retention.

Much went wrong, no structural design, additions later, terrible welds, no results.

Therefore the construction was halted.

I arrived that winter and discussed the situation with the owners.

So take the wooden frame down..

Design a roof with the available materials,
apply the rules set by Pablo (the local roof expert)..

Wishes:
- Use recycled materials that were already bought.
- Create a shaded area around the building.
- Build a chimney in the center of the living room.
- A room on top of the living room.

Demands:
- A frame to support the roof.
- Only 2 m spans with the chosen beams.

Therefor I choose to separate the roof into three pieces. An external roof for the shade (made with garden branches, cheap materials), spanning from the building to the offset ring.

Atop the building itself a smaller roof (using the materials provided) and a central chimney. On top of the chimney we'll place the third roof.

The owners had many chickens so I was thinking of a chick hatchery in the second roof, letting the chicks walk out onto the first roof.

The second roof has an opening around the chimney where hot air can escape because the sun passes straight over this spot and it gets really hot in Portugal.

The central chimney can be used to support the roof. This creates a big open space that can be used as a room.		The roof is continued along an offset ridge towards the other side of the house. This creates an opening where a staircase can be added.

The first roof can be made from all remains from the second roof plus any materials that can be found.		The first roof will create a hot-air rise into the second roof. This seeps into the second roof that creates a vortex.

I can choose whether the staircase is placed on the north or south side of the building.		After consulting the owner, the air vortex should flow clockwise. The chimney gets offset holes further amplifying the effect.

No further expenses were possible though, so the roof was not started again.