Concrete provides a perfect alternative to conventional, endangered building materials, particularly lumber, and offers the strength and beauty sought by home buyers. The Portland Cement Association describes some of the many advantages that make concrete an ideal material for residential construction: Concrete is environmentally sound. It replaces a natural resource, lumber, in construction and instead relies on abundant natural resources. It is safe: durable enough to withstand hurricanes, tornadoes, fire and water. Concrete offers a wide variety of style options and is an energy-efficient material that can save homeowners money on heating and cooling costs. International Form Corp., Jacksonville, Fla., has developed modular housing systems that combine the best aspects of concrete with cost-efficient, modular precast systems. Most recently, they have introduced a modular housing project, that fully exploits the advantages of concrete over more limited resources. The fully automatic process creates a monolithic, five-sided (four walls and a roof) module. Usually, two of these cured modules are set on a slab of poured concrete, joined together, and protected by a precast roof that bridges the space between them. Because the construction process is fully automatic and creates a seamless module, modular housing saves labor and can be completed quickly. International Form Corp. says that it is possible to pour, cure, remove, and load the module within 24 hours.