If you are thinking of buying an old cob walled home or building a cob house in Portugal or are already in progress building a taipa walled house. Here is some advice from Castelo Construction.
For anyone new to Cob or Rammed earth, also known as taipa in Portugal. It is a technique for building walls, foundations, and floors using natural raw materials such as earth, chalk, lime or gravel.
It is an ancient building method that has seen a revival in recent years as people seek more sustainable building materials and natural building methods.
Rammed-earth can be simple to construct, non-combustible, thermally massive, strong, and durable. Structures such as walls can be labour-intensive to construct without machinery (powered tampers), however, and they are susceptible to water damage if inadequately protected or maintained.
Cob or rammed-earth buildings are found on every continent except Antarctica, in a range of environments that include temperate and wet regions, semiarid deserts, mountain areas and the tropics. The availability of useful soil and a building design appropriate for local climatic conditions are the factors that favor its use.
We come across homes constructed wholly or in part of taipa in central and southern Portugal.
There are two main considerations when planning building or renovation a cob/ taipa home.
1, Earthquake resistance – Taipa / rammed earth using rebar, wood or bamboo reinforcement can prevent failure caused by earthquakes or heavy storms, since un-reinforced structures have extremely poor earthquake resistance.
2, Insulation – Hybrid buildings that use insulated framed external walls with rammed earth internal walls and feature elements can achieve high insulation and high mass.
Insulation can also be added within the thickness of a rammed earth wall but this adds to its cost and changes the structural properties of the wall. However, it does provide the benefits of both excellent thermal mass and good thermal insulation in the one wall while retaining the desirable look, texture, feel, acoustics and low maintenance properties of the facing of rammed earth on each side.
The best location for insulation when used in conjunction with rammed earth is on the outside face of the wall, so that the thermal mass is within a contained and controllable external envelope
For more information click this link https://en.wikipedia.org/wiki/Rammed_earth
For up to date technical advice on all aspects of construction contact Castelo Construction