Flooding is the most common of all environmental hazards. It regularly claims over 20,000 lives every year and adversely affects around 75 million people world-wide. The reason lies in the widespread geographical distribution of river floodplains and low-lying coasts, together with their attractions for human settlement because of the fertility of the soil and the importance of the fishing industry. Over some flat deltaic countries rainy season flooding regularly covers an estimated 20% of the total land area and very high floods may cover half the available land. The December 2004 Tsunami disaster in South and South East Asia has removed any remaining complacency over the possible consequences of natural disasters. People of goodwill respond to dramatic images with customary generosity. However, much of the expensive relief activity does nothing to prepare for future events or to re-establish the everyday livelihoods of the people caught up in the tragedy. Nature is too powerful to keep under control at all times. Flash flooding from storms falling on urban areas or deforested hillsides result in vast quantities of water rushing through towns and villages. Sea defences can only cope with normal tidal surges; tsunamis penetrate far inland exerting forces which cannot be resisted except by exceptional civil engineering measures. Giant single-purpose emergency refuges for times of flood have been constructed in Bangladesh. But then people have to return some distance to what is left of their homes after the floodwaters have gone down. The more logical step is to provide safe refuge right in the locality – a building that is used daily, not just in times of flood, and

which accommodates, rather than confronts, a torrent. In this way we learn to live with floods. A pilot project undertaken by the Wesleyan Methodist Church in Mozambique, supported by MRDF (Methodist Relief and Development Fund) has demonstrated that it

is possible to provide local flood-proof buildings requiring only a small team of people and low material use, with all building components manufactured on site. This approach can be replicated elsewhere to reduce loss

of life and property damage at time of flood. By employing local resources and using the skills and energies of the local people, it also creates new livelihoods, alleviating poverty.

1

HIGH AND DRY CONSTRUCTION FOR VULNERABLE AREAS OF THE WORLD

THE HIGH AND DRY CONCEPT Knowing that the floods will come again one day, a

community should have a place to go

which has an everyday purpose, but will provide a

safe refuge for many people. In due

course all homes should have a

HIGH AND DRY area.

School children in Mozambique point to their new HIGH AND DRY classroom

Houses with solid walls are demolished by powerful

floods but, with an open frame ground floor construction, the

water passes underneath leaving the upper floor HIGH

AND DRY

The concept was developed by Parry Associates in a practical exercise at their Cradley Heath headquarters in the UK. The object was to design the new elements of the system and demonstrate the effectiveness of the building technique, which involves a deeply coffered raised slab forming the raised floor. The construction system is modular, based around a near-cubic frame comprising concrete columns and beams formed from standard concrete and steel reinforcing bars. The beam elements are made up of individually moulded sub-components – cavity blocks - into which the reinforcing bars are embedded in fresh mortar during construction.

The design of the raised floor consumes less concrete than a solid slab and eliminates the need for expensive plywood shuttering and formwork. The slab is supported on slender concrete columns, engineered to a standard similar to the posts of a pier or pedestrian bridge. A new hollow coffer assembly has been the main innovation. These modular hollows were initially made of micro concrete and left in place. Subsequent development led to the use of flexible moulds which can be used over and over again, simplifying the manufacturing process. The moulds are then temporarily supported in position by bush poles (which are also used over and over again), whilst concrete is poured over reinforcing bars placed in the valleys between the rows. This forms a grid of beams between the columns. When the concrete is set the bush poles can be removed and used for the next section of the floor.

To ensure the practicality and ease of operation of what would be an innovative system, the Cradley Heath work team undertook a series of design and manufacturing tasks. Several building exercises were undertaken in the UK to prove the construction equipment and methods proposed. The final exercise involved construction of a complete section of raised floor including casting the slab. A roof was erected over the upper floor, again comprising roofing tiles produced on site using the same equipment that produced the column and beam elements. In practice the householder would apply whatever materials are locally available to build the upper storey – as if building at ground level. The concept proceeded to overseas implementation, starting with the aftermath of the catastrophic floods in Mozambique in 2000. Since then ‘High Schools’ (HIGH AND DRY buildings built as school classrooms) have been constructed in Lionde and Nconhane, with a third project under way at Malkazene: all in the area of Gaza Province, hardest hit by the Limpopo flooding.

HIGH AND DRY CONSTRUCTION: DEVELOPMENT PHASE

2

‘High School’ proposal for Mozambique

Cross section of the raised floor, after props taken our and before removal of the coffer formers

Rubble and waste items added to save cement

Reinforcing bar

Coffer former

HIGH AND DRY A single core based

on a contractor’s weekly output

Preparing raised slab for casting

HIGH AND DRY: IN MOZAMBIQUE

The Wesleyan & Methodist Church of Mozambique had been carrying out community programmes in the Limpopo valley for some years. With the flood disaster in year 2000 and the prospect of recurrence due to climate change and other factors, the church began to cast about for solutions which could provide defence against floods. Meanwhile, staff at Methodist Relief and Development Fund (MRDF) in London were aware of certain building projects to which it had contributed, notably in Sri Lanka and Sierra Leone, which were based on building elements – roofing and wall blocks, etc., – manufactured on a small scale near the point of use from locally available materials. As the projects had been successful, both technically and as generators of local employment, MRDF had begun to exchange ideas with the originators of the production and construction systems: West Midlands engineering firm JPM Parry & Associates Ltd. As news of the flood disaster in Mozambique unfolded, Parry Associates quickly produced a design concept for a two storey building which could be constructed from local materials using an extension of the firm’s proven technology, and which would offer very substantial savings in comparison with conventional multi-storey building techniques. The upper storey would rest on a securely founded frame and would provide a substantial area of refuge for people and stores in time of flood. The concept design was presented as a classroom, hence the original title ‘High School’, but it could be used for almost any other communal or private purpose under the description of the HIGH AND DRY construction system.

MRDF consulted the local Methodist Church in Mozambique to ascertain whether it agreed with the validity of the concept and could provide resources to undertake a pilot project. Their response was positive in both respects and the project was initiated.

MRDF agreed to provide funding in the UK to cover manufacture and shipment of special production tooling, and to assist a local church to provide the organisation and funding for a first HIGH AND DRY classroom project in Mozambique’s Gaza Province. After completion of the first project, at Lionde, a second application was initiated and completed during 2004 at Nconhane. A third ‘High School’ at Malkazene is now under construction and is planned to be opened in July 2005.

It is estimated that by mid-2005 high quality, safe refuge will have been provided for over 1,000 people in buildings which at normal times provide classroom accommodation for the school children of the three villages. The precedent created by the Mozambique project is potentially valuable to other situations where fears of future flooding need to be taken into account in plans for reconstruction associated with sustainable development.

3

One of the new HIGH AND DRY

classrooms in Gaza Province,

Mozambique

HIGH AND DRY: HOW THE SYSTEM WORKS

4

THE CONSTRUCTION ELEMENTS The special elements required to support the raised floors using the Parry HIGH AND DRY system are: 1. Hollow column blocks 2. Column top slabs 3. Shuttering slabs 4. Hollow rectangular blocks for ground and wall beams These are all made on site on a hand powered, large format vibrating machine, using special moulds designed and produced for the purpose Comprehensive training is given for making the elements; descriptive and illustrated manuals are provided. The production site requires availability of water, but electricity supply is not necessary. The manufacture of the wall and beam building elements is based on vibrated concrete shaped in re-usable moulds. Vibrated concrete results in a stronger, lighter product with consequent savings, especially in cement and roof timber. Columns are founded in a 400mm deep concrete base and constructed of pre-cast concrete blocks and reinforcing bars. The raised floor is constructed with rows of 600 x 600mm cavities in the underneath surface formed by coffer units, which are laid on bush pole props accurately located by spacers. Reinforcing bars are positioned between the coffer domes; shuttering panels are positioned around the floor extremity rising to 10mm above the domes; concrete is poured to fill the space up to the top of the shuttering, and consolidated by tamping or vibration. (A conventional raised floor would require nearly twice the amount of concrete and cradling in 18mm plywood shuttering which is usable, on average, twice only.) Once the slab is complete, a conventional building can be erected on the raised floor from vibrated concrete elements, with wall blocks, window frames and roof tiles – or by reverting to materials and methods traditional to the area. The ground floor can be left open-sided to present no resistance to fast flowing water. If walls are constructed between the frames, non-structural materials should be used which readily give way under pressure of deep, fast flowing water so this passes through the lower storey, leaving the upper floor HIGH AND DRY and the occupants and contents safe from harm. DURABILITY AND SERVICEABILITY Although the HIGH AND DRY concept is innovative, all structural calculations and working procedures follow established orthodoxies and adhere to ‘best practice’ for this type of high performance structure.

Shuttering panels in place awaiting installation of

reinforcing bars and pouring of the concrete slab

Coffer former

The concrete fill forms a grid of beams

Edge shuttering panels

Column blocks

Reinforcing bars

THE RAISED FLOOR CONCEPT

The strength of the slab depends upon the steel reinforcement placed between the hollow coffers which, once concreted

into position, form a series of beams

Construction of blockwork columns tied

with reinforcing bars

Horizontal beams made by joining ‘V’ blocks with steel

reinforcement grouted in with fresh concrete

METHOD OF CONSTRUCTING THE HIGH AND DRY PLATFORM

5

Substantial foundations are laid for the columns, which are reinforced by accurately positioned bars. The columns of blocks are built to the raised floor height of 3 metres above ground level.

Column caps are mortared to the tops of the columns and the column reinforcing bar ends are joined to the reinforcing bars of the slab. The vertical reinforcing bars are nested into the cutaway corners of the blocks and then grouted into permanent position, using fresh cement mortar. The coffer moulds are then lifted into position (top right)and supported on props made from bush poles obtained locally. A ‘claw’ device holds the square coffer moulds together at the corners.

Right: At the point where the coffer moulds meet the corner cap, the claw goes into the cavity in the corner of the cap holding the adjacent moulds in position

Right: An area of coffered floor slab viewed from above. On the extreme right the concrete in-filling is in place; on the left the moulds are still exposed

The vertical reinforcement bars extend up-wards through the slab to provide a means of tying the upper floor superstructure in place. Ideally this should be based on further col-umns, the same as those which support the raised floor. The tops of the columns can be linked by a ring beam joining all four columns.

Below right: a school in Mozambique, demonstrating the HIGH AND DRY construction method

THE EQUIPMENT KIT AND THE PRODUCTS

6

MANUFACTURING TOOLS HIGH AND DRY building technology is based on a series of moulding tools used with a vibrating table, powered manually or by a 12V DC electric motor. A Vibrating table B Column block mould C Column top cap mould D Mould for standard wall

blocks E Mould for ground and

wall beams F Mould for slab side

shuttering panel G Multi-stacking units H Moulds for roof ridge

tiles I Moulds for roof tiles

CONSTRUCTION TOOLS J Coffer formwork units K Coffer formwork frames L Claws for supporting slabs M Roof tiling template

The amount of equipment supplied to construct a 3m x 3m core slab will include 25 formwork sets, including claw brackets used with locally supplied bush poles to prop up the slab for one week

The pre-cast equipment manufactures the correct number of products needed to construct foundations, ground beams, columns (including top capping), wall

beams and roofing to cover the upper floor. A detailed manual specifies the details of the reinforcing steel and the concrete mixes used.

Production equipment supplied will be sufficient for a 2-3 person team to make elements for one core in a week.

THE PRODUCTS

Column cap

Roof Ridge Tile

Side shuttering panel

Hollow block

Roof tiles

Beam block

Column block

Coffered slab seen from below

HIGH AND DRY: BENEFITS FOR THE POOR

7

The HIGH AND DRY concept is designed primarily for people dwelling in flood-prone areas where capital is relatively scarce and labour is relatively plentiful. For such communities the system offers the following advantages and opportunities: REFUGE AND ACCOMMODATION For people whose occupations require them to live in areas with the risk of flooding, a HIGH AND DRY upper floor provides a secure area where they and their most precious possessions can remain, either until a minor flood subsides or – in extreme circumstances – until rescue by emergency services. The upper floor becomes the ‘core’ of the dwelling but, being modular, is capable of extension into a wider, longer building.

EMPLOYMENT A HIGH AND DRY construction project employs people from the immediate area, operating hand-powered equipment to produce building elements; gathering sand, aggregate and bush poles; constructing columns; and pouring the coffered

concrete platforms. Besides the incomes generated, the sense of common purpose in a vulnerable community will be highly positive. BUSINESS OPPORTUNITIES Initial construction of raised platform buildings is likely to be led by an NGO until the business parameters are fully recognised within the community. The system offers excellent scope for small business activity with low cost equipment,

easily learned skills and relatively straightforward management. An NGO can encourage a move towards an independent commercial operation if it intends to withdraw after launching the enterprise, or it can continue to organise the activities with direct labour or small sub-contractors as a livelihood-generating mission. INDEPENDENCE The existence of secure areas will change many attitudes, e.g. to investment in manufacturing facilities and to property development. It will encourage enterprise and the move from subsistence to the generation of a saleable surplus. The circulation of incomes will advance the integration of the community into the formal economy, giving its people ever greater control over their lives. In summary, the HIGH AND DRY concept has the potential to mobilise community effort to bring important and beneficial changes to people’s lives. It promises to be good value for money as a development initiative eligible for humanitarian support during the introduction phase then moving into self-sustaining small enterprise.

Left to build with indigenous materials, poor people’s homes are sometimes so flimsy that their possessions and accommodation can be

swept away in a few minutes

Parry-trained technician from the Gambia providing instruction to builders in Malawi.

Transfer of skills can be done ‘South to South’, with technicians from one country travelling to

another land to introduce new groups of trainees to new skills, such as roof building

Small beginnings with just two or three workers engaged in production can grow into larger

undertakings once business becomes established

LONG TERM BENEFITS FROM POST-DISASTER RECONSTRUCTION HIGH AND DRY house cores to improve and protect lives

8

Parry Associates are introducing an affordable, easy-to-construct raised platform for flood-prone settlements. HIGH AND DRY house cores are designed so that the flood can pass underneath a secure room built well above the water level on top of the platform. The platforms and supporting frames will provide a structurally-robust and protective core to informally-constructed sections of the dwelling. The HIGH AND DRY concept derives from experience gained during the aftermath of previous flood disasters in Mozambique’s Gaza Province in 2000, and Northern Honduras in 1999. The approach seeks to combine early provision of shelter with resumed livelihoods, more durable accommodation and greater security for the future when other inundations may occur.

HIGH AND DRY platforms comprise the use of light but robust frames pinned to the ground by vertical post foundations with flat, lightweight coffered floors, raised 3 metres above ground level. The frames are modular, approximately

cubic in proportions, 3m x 3m x 3m. The materials used are bought from local suppliers and all manufacturing and construction activities are performed by local people. Production of the building elements and the subsequent construction is performed using a kit of equipment which provides for the local manufacture of high quality wall, floor and roofing products. These will be saleable in the local market – a basis for a sustainable local business. There will need to be a training phase, creating the vocational skills for small producers and contractors to acquire for delivering the technology, and pilot programmes in the areas concerned to make the public, businesses and government officials aware of the potential benefits. The provision of the modular house cores, installation of which involves primarily local resources (materials and labour), could become a subject of targeted sponsorship, to assist the lowest income families. Individual units could be constructed by local manufacturers/contractors for under £500 each. NGOs working with the local authorities will be able to identify suitable beneficiary households, while western organisations such as charitable foundations, churches, mosques and schools may raise sponsorship funds to pay for HIGH AND DRY house cores.

San Pedro Sula, Honduras: workers making tiles using Parry equipment after the

flood disaster destroyed the local village

For further information contact: JPM Parry & Associates Ltd, Overend Road, Cradley Heath, West Midlands, B64 7DD, UK

Tel +44 (0) 1384 569 171 Fax +44 (0) 1384 637 753

Email: info@parryassociates.com www.parryassociates.com

Vision of newly-built HIGH AND DRY house cores integrating into a small town in Sri Lanka