Auckland Region VillageTown

A Fireproof Village through the use of a single bulk material

Why will almost all the village be made from a single bulk material called Variable Density Concrete (VDC) and what is VDC?

To answer the second part first, VDC is standard concrete with an additive that looks like shaving cream – a foaming agent that allows a precise amount of air bubbles to be added to the concrete so when it cures it is lighter and less dense, which means it offers a higher fire rating (as much as five hour), excellent thermal and acoustical insulation, and most importantly, the ability to build a floor, wall or roof out of a single bulk material. It is made on-site, like normal concrete. It is low-cost & highly flexible in application.

Think about it: The conventional wall, no matter what it is made of, consists of different parts that have to be fabricated and installed, often by hand, greatly adding to the cost and complexity (especially in scheduling trades), with numerous inspections and different professional qualifications to get a wall built. If one builds using normal concrete, one then must batten the inside to allow for insulation, and then the battens must be clad, usually with wallboard that must then be finished and painted.

If instead we replace complexity with a single bulk material, we need to accomplish the following elements:

• Must meet thermal & acoustical insulation requirements. VDC does this with a thicker wall.
• Must meet or exceed fire ratings. VDC does this by using a material that does not burn.
• Must meet structural requirements. VDC does this because it is reinforced concrete.
• Must be durable. VDC does not rot, resists termites and insects, is not affected by UV.
• Must be affordable. Concrete is universal and inexpensive, especially if it needs no cladding.
• Must be beautiful. VDC is plastic, meaning it can be moulded to any type of form.
• Easy to inspect – In the real world, building inspectors are people who work best with familiar materials. While new materials will gain approval eventually if they merit it, using concrete raises no issues or concerns. Additives in concrete have been used for generations, and should raise no concerns as long as they are certified, which the foaming agent is.

Why will we use a single bulk material, VDC, for most village buildings?

1. Speed
2. Cost
3. Insulation
4. Fire Rating
5. Flexibility in design (Aesthetics)
6. Durability

Please explain:

• Speed – Unlike a conventional development where sales depend on people getting jobs in the regional economy, in a parallel village sales look to a global market, on people bringing their jobs with them. Indeed some of those jobs depend on the village achieving a critical mass; certain businesses require a minimum population in order to operate profitably. To assure sales, a conventional development needs to be built in stages. In contrast, a parallel village must be built all at once. This creates the need for speed; buyers cannot wait years for their place to be built. Once construction begins, it needs to be completed in short order – perhaps 12 months or so. Otherwise financing may prove to be too great a burden. To accomplish this one needs a construction system that more resembles a modern factory than the conventional job site where assembly tends to still be bespoke. Given that upwards of 4,000 buildings will be constructed in 12 months, it creates an opportunity to implement a manufacturing system with far higher efficiencies than the normal construction project.
• Cost – When costs are contained, the village secures additional funds to provide amenities. Amenities such as the artist guild halls, the plazas, the greenbelt, to name but a few, become affordable if savings are realised elsewhere. After examining many different building systems and methods, we concluded that for high volume construction, building in-situ with standing forms and moulds offers the best solution. Bulk materials… cement and crushed rock or sand are brought to the job site in the most efficient form… solid packed. Given the volumes cement can be purchased by the shipload or trainload and moved directly into silos, with no bagging. Mixing and certification testing occurs on site and wet concrete is then pumped into the standing forms. When it sets, the forms are moved to the next building using mobile cranes.The form system enables workers to install doors, windows, pipes and conduit and then pour the concrete around them, thus locking them in place. This is significantly easier than conventional fitting. The forms have plastic custom-computer-cut moulds inside them so the final walls are shaped.
• Insulation – VDC enables very high insulation ratings, both thermal and acoustical. While thermal is environmentally important, acoustical is essential in a medium density community where homes share a common wall. Hearing the neighbours is a major source of irritation in medium and high density living.
• Fire Rating - While the dreadful fires in Australia’s suburbs raise another reason to build a development using materials that do not burn, the prime reason for the parallel village has to do with the width of the streets – avoiding what is called design by fire truck. The parallel village needs to be human-scaled. This means not designing streets to support on-street parking and two ton vehicles hurtling by at speed. But it also means that one must eliminate the need for large fire trucks and apparatus. While they may not be used often, street engineers will insist the streets be wide enough to provide for public safety. If one builds a development using materials that do not burn, setting out fire hoses as part of the development and requiring any building with flammable elements in its structure (such as a wood-panelled room) to have sprinklers, then fire safety is addressed without needing wide streets.
• Flexibility in design – Speak of concrete slab housing and many people think of Soviet block housing – uniform and utterly plain, dismal and depressing. Indeed, concrete can be depressing, it is too dense. Variable density concrete overcomes the density issue, but if it were to be poured into flat forms, the visual aspect can be unattractive. Introducing new technology: Today one may purchase a very large flat-bed carver that is a 3D printer able to carve in plastic (or other material) almost any shape. One may take a 3D photograph or make a 3D CAD design and the “printer” will carve it in reverse. Using soft plastic moulds one can even hire a skilled carver to hand carve a mould. These moulds are then set in the upright form, and when the VDC is poured, the wall is shaped. In this way, ornament and detail is only restricted by the talent of the designer or architect. Indeed, one can even do a home that looks timber clad, except it won’t burn, rot or attract termites.
• Durability – Concrete lasts. Because parallel villages are intended to endure for generations, they need a bulk material that lasts for centuries. Once built, it would be hoped that the village will not see homes or workplaces constantly being torn down and replaced, but rather that it will be a timeless place that serves peoples needs - where the buildings do not wear out.