Putting It All Together
The previously cited link to the ACI Concrete International magazine ("Disaster-Resistant Shell Houses" [PDF], May 2008) shows different stages of the assembly of an all-concrete disaster-resistant house. Joint details must positively connect the roofs to the walls and to the foundations.
The design concept is completely sound from the standpoint of providing safe structural shells. It meets the conditions of ACI 318 Building Code Requirements and ACI report 550.R1-09.
(a) Concrete walls are erected up to the roof level
(b) Foam-lined forms for ridge and valley beams are erected
(c) Forms are installed for the overhangs and eaves
(d) ICF roof planks are installed and the concrete is ready to be placed
Figure 9. Construction sequence for a compound roof with concrete walls and insulating roof plank on concrete walls.
Animated House Assembly video
This link leads to an interesting animation showing the construction of a reinforced concrete house utilizing insulating concrete forms (ICFs). Produced by an Irish company, Eurozone Building Solutions, the video shows assembly of all of the elements fundamental to creation of a disaster-resistant two-story house utilizing insulating concrete forms to create the outside reinforced concrete load-carrying shell of the house. This house may also be designed utilizing the Emulative Detailing principles shown in ACI publication 550.1-R-09 as well as the provisions of ACI 318 Building Code Requirements.
Roofing
The approach illustrated here utilizes insulating concrete form roof planks which are universally available on the market throughout North America. This technology is well developed, widely available, and is being used more and more, as documented in the cited article about disaster-resistant shells.
If constructed according to code-required specifications, it is quite feasible to allow the concrete roof slab to remain uncovered by any other roofing material, an offset to the structural cost of a concrete roof. Conventional roofing materials have been stripped off by tornado winds. A crystalline water-proofing admixture or surface treatment should be used. On the island of Guam where the annual rainfall is about 100 inches, such roofs are left exposed. Roof finishes might feature stamped concrete simulating shingles or tiling, colored pigments and/or water-repellant coatings.