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| VERSION FRANCAISE |
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History |
| Lightweight Earth Concrete |
| Multilayered Carpentry |
| Public Declaration |
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ECOLOGY |
| NATURAL MATERIALS |
| BEN'S WORK |
DESCRIPTION
It has an insulation value around half that of glass-wool (lambda = ~0.07). A roof 40 cm thick has a thermal resistance (R) of 6 or 7. Its fire resistance is of the order of M1 or M2 and its useful life will be a lot more than 10 years.
HISTORY
The beginning
It was in 1992 that I found an old adze among the rubbish, which I recognised by its shape and the steel which was harder than a hoe.
Unbaked Earth
Fire Resistance
Carpentry with square wood
Reflecting on these two facts led me to observe that traditional roofs are made from square sections in a number of layers; battens, rafters, purlins, truss frames. I reasoned that if each element of an upper layer was fixed at each intersection to an element in a lower layer, to share the load, we would gain efficiency.
I calculated the resistance of the battens used and quickly concluded that a widespread distribution, and the possibility to concentrate the support where it was needed, could be obtained with smaller battens and more layers. On the other hand the fixing time increased with the number of elements.
A balance between these two considerations led me to make more serious calculations. The optimal size came out at 4cm x 4cm. Battens of this size can easily be fixed using self-tapping wood screws. Multilayered carpentry was born.
LIGHTWEIGHT
EARTH CONCRETE
STANDARD
CONSISTENCY
What is Lightweight Earth Concrete (LEC)?
The woodchips should be air-dry, around 15% moisture content. Green woodchips, covered with sap, adhere better if they are washed by the rain and dried in the sun. During this process, they should be turned regularly to prevent them from fermenting and the possibility of spontaneous combustion.
The woodchips and mud are mixed with 20 to 30 litres of mud for 80 litres of woodchips by hand or in an ordinary concrete mixer, poured into vertical shuttering or onto more or less horizontal shuttering and tamped or vibrated. Vertical shuttering can be removed after several hours.
Lightweight earth concrete sets by the evaporation of the water and the formation of electrostatic links between the micelles of clay and the woodchips. The drying rate, within the limits of the possible, that means < 60°C, does not modify the integrity of these linkages.
When dry the LEC typically has a density of 4-500kg/m³. The carpentry that supports it must be calculated with regard to this weight plus the weight of additional charges.
Fire resistance experiment:
(en construction)Persistent leak experiment:
(en construction)MULTI LAYERED CARPENTRY
What we all know
It is this web, filled with lightweight earth concrete that becomes wall, roof, partition, ceiling, floor, pillar, arch.... The distribution of the battens throughout the volume provides a uniform and flexible support. The concentration of the battens around the critical points assures optimal resistance.
Mathematical model :
Consider the elements in a horizontal structure.
The setup shown to the left is a simple junction between three elements, disposed in three layers.
Each element contributes : 85.33 / 2 = 42.67 cm³
Viewed from left to right the central element contributes its moment which is : 10.67 cm³
This value must equal the sum of the moments previously calculated. We can ensure that this is the case by adding elements to the structure.
PUBLIC
DECLARATION
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Peter Lorien, the system's inventor, offers it free to the world |
N© |
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This is freeware, please acknowledge it with help to develop and spread the system. |
Demonstrations, technical assistance & short courses available on demand. |
| Site : http://lorien.free.fr |
Mail : lorien@free.fr |
| Declaration in the public domain | 15 February 2001 |
WHAT IS THE TECHNICAL DESCRIPTION OF THE INVENTION?
Wood reinforced lightweight earth concrete, (WORLEC). A construction system which comprises a wooden armature filled with lightweight earth concrete.
TECHNICAL DOMAIN IN WHICH THE INVENTION APPLIES?
It is used in the construction of relatively flat parts of buildings; e.g. walls, floors and roof surfaces.
WHICH PROBLEMS DOES IT PROPOSE TO RESOLVE?
It addresses two categories of problems encountered in building construction.
- The first is the contradiction between the structural and the protective functions of a building.
The structure of a building presents a support for the protective elements such as thermal insulation, acoustic insulation, rain and wind resistance and hygrometric stability to maintain the internal atmosphere in the comfort zone.
It must be solid enough to support its own mass and that of the occupants and their belongings, and it must be strong enough to resist the impact of the external forces that can be anticipated.
We are frequently required to make compromises or to make complex structures.
I will address these compromises more precisely when I consider the existing solutions.
- The second are of an ecological nature. The problems in this category are related to the high cost of the energy required in the manufacture and transport of building materials; or to the chemical or fibrous emissions given off during the construction, useful life, or the demolition, of current constructions.
WHAT SOLUTIONS, TO YOUR KNOWLEDGE, HAVE, UP TO THE PRESENT BEEN BROUGHT TO BEAR ON THE PROBLEMS THAT YOUR INVENTION PROPOSES TO RESOLVE?
- Concerning walls:
The contradiction between the solidity of a structure and its thermal isolation is manifest in the case of masonry or reinforced cement concrete structures.The proposed solutions are to use hollow bricks or blocks, no-fines or expanded concrete, or adding insulating fillers. Timber embedded in cement or lime is subject to fungal attack. Masonry, especially when it is rendered with plaster, dries the atmosphere inside the building. It is complicated to produce earthquake resistant masonry. The raw materials, requiring large amounts of energy for their manufacture and transport, have a high ecological cost.
Modern, composite, timber-framed structures resolve this contradiction by means of assembling complicated multi-layered structures using many different materials. There remain problems of waterproofing, condensation and acoustic insulation which are not fully resolved. The ecological balance-sheet starts with the emissions given off by the chemical products used to protect the wood and the fibres used for insulation, both during the construction and the useful life of the building and returns when we have to demolish these complex structures.- Concerning roofs:
Traditional carpentry uses an excessive quantity of wood being based on the principal that each layer must support those above and itself. It has no redundancy and requires qualified workmen to produce it. It is difficult to insulate.
Roofs built with lightweight truss frames are difficult to insulate to a great thickness. Their mass is not sufficient, in themselves, to prevent the roof from flying off in heavy winds. Similar remarks to those above mentioned apply to the products used to protect the wood.
- Concerning floors
Floors made with concrete beams and blocks require additional insulation and fall down in earthquakes. See my remarks in relation to masonry walls.
Wooden
floors display problems with acoustic insulation and fire-resistance; and need
to be protected with chemical products.
- Concerning fires:
In spite of being built to the norms, classical roof and floor structures often fall, before the occupants can escape. The prolonged stability of a building on fire is only to be welcomed.
EXPLAIN IN DETAIL THE STRUCTURE AND FUNCTIONING OF AT LEAST ONE WAY OF APPLYING THE INVENTION ILLUSTRATING YOUR EXPLANATION WITH DRAWINGS AND EXAMPLES.
figure 1
Typical example of a more or less horizontal structure employing 10 layers.
figure 2
Typical example of a vertical structure employing 7 layers.
The armature consists of superimposed layers of parallel strips of identical dimensions; each layer being fixed at an angle different from the preceding one.
The strips can be more or less square or round and can be of wood, bamboo or bundles of fine stalks.
The layers are fixed together at each intersection by means of bolts, screws, nails, dowels, rivets; of metal, plastic or rawhide; or with cords.
These multiple fixations offer a high degree of redundancy, which insures stability in the case of damage to the structure.
The number, dimensions and spacing of the strips are calculated to support the determined load within the total thickness chosen for that element.
This thickness is determined from the degree of thermal insulation required and the thermal resistance of the infilling material.
A continuous horizontal layer is fixed to the foundations at the bottom of the walls, above and below openings and at the junctions between walls, floors and roofs, within the diagonal layers and using the same materials.
One or both of the outside layers could be of traditional timber-framed construction, either existing or made to measure; the shuttering being fixed to the outside of this framework with a layer of elastomer foam, or panels of polystyrene, plywood or fibreboard cut to fit between the framework, to set back the concrete to make space for the rendering. The armature being set into the infilling, no extra support is necessary between the timber frames.
To improve acoustic insulation adjacent layers can be made to move independently by means of inter spacing them with blocks of a soft material such as cork or fibreboard.
The necessary trunking and pipe work are placed within the armature before fitting the shuttering.
This armature is shuttered either by means of a permanent shuttering which remains in place made from masonry, weather boarding or wooden, chipboard or straw board panels, or strip mats to take a rendered surface ; or by shuttering made from wooden or metal panels, full and covered with paper to prevent sticking or in the form of a mesh ; fixed to the armature with screws, nails or bolts which traverse the element or supported on props in the case of more or less horizontal surfaces; which are removed after the infilling has solidified.
In preparation for a rendered finish the shuttering can be spaced from the armature by means of blocks so that no wood remains apparent.
The armature covered with shuttering is poured with earth concrete made from a clay mud, filled with cellulose particles such as chopped dried plant materials, straw, paper or fibres; or wood chips; or other insulating materials such as expanded clay, vermiculite or plastics. The cellulose fillers can be waterproofed with silicone or wax in order to speed up the drying process and to make the material waterproof. The concrete can be poured manually or by means of a blower and is compacted by vibration. The degree of compaction and the proportions of the mud and the filler determine the degree of solidity and inversely the level of thermal resistance of the element. Different particle sizes in the filler influence the solidity and the sound insulation at specific frequencies.
As soon as the earth concrete has solidified, the shuttering can be removed and after thorough drying, a plaster, lime or earth rendering can be applied to the exposed earth concrete; or panels of other materials can be fixed to the walls and ceilings.
The roof can be covered with sheet roofing, tiles, slates, shingles or thatch fixed by traditional means, the outer layer of the armature taking the place of the battens normally employed; or set in a lime or earth mortar.
Floor surfaces can be finished with the planks and wooden tiles normally available, or they can equally be finished with beaten earth or a lime mortar to take ceramic tiles.
No waterproof film is required because the earth concrete, being permeable to vapour, it is preferable that it respires from both sides. It is therefore important that the external finish is impermeable to liquid water but ventilated if it is not permeable to vapour.
WHAT SOLUTION DOES THE INVENTION SUPPLY?
The proposed system can be used for all flat elements within buildings, even for the panels used in geodesic domes and zomes and to construct pillars and arches. It is even easy to make curved forms.
It is constructed with only one size of strips without any difficult cut joints.
At one and the same time it satisfies the structural and thermal insulation requirements.
It can be easily built without the need for specialised tools or workers, with materials available locally almost everywhere.
Its vapour permeability avoids the use of impermeable products thus eliminating condensation and the need for air conditioning.
There are no thermal bridges.
It has a high level of acoustic insulation both for airborne and transmitted noises. Built from multiple continuous layers, it will be earthquake resistant.
The lightweight earth concrete filling has a high degree of fire resistance protecting the wood for several hours, and it also protects against wood boring insects and fungus attacks, with the exception of termites.
It must be protected at ground level against termite attack in affected zones.
WHAT DO YOU BELIEVE TO BE THE ADVANTAGES OF THE INVENTION?
The advantage of this system of construction rests in the simplicity of its methods of construction and the local availability of the basic materials almost everywhere as well as their natural qualities.
It may well be the cheapest way to construct buildings.
In horizontal elements there is a saving in the amount of wood used as the upper layers are solidly fixed to the lower layers and help to support them.
It can be used to construct all imaginable forms, even complex curves and large or multi-story buildings.
It satisfies all the demands that we make of buildings in relation to their structural, and thermal or acoustic insulation requirements; (given the thickness of the insulation which goes all through each element, it presents the quality of super insulation permitting no heating requirement throughout much of Western Europe).
The use of clay with its vapour permeability contributes to the control of the hygrometry inside the building.
It is fire resistant (which can be improved by treating the wood with a fireproofing agent), earthquake resistant, hurricane resistant and flood resistant (with waterproofed filler), and the wood being unexposed is protected from insect and fungus attack without using dangerous or toxic products.
It can easily be taken apart offering the possibility of recycling the wooden elements into other structures. The earth concrete can be remixed with water and used again, or thrown on the ground where the cellulose materials will become compost with the earth and clay.