In the United States semi engineered residential buildings

In the United States, semi-engineered residential buildings are also very prevalent, and these building types are also often most vulnerable to high velocity winds. This is evidenced in the aftermath of the numerous storms that have ravaged the southern coast of the United States over the years. Hurricane Katrina for instance, one of the strongest and most extensive storms to make landfall on the coast of the United States, caused the destruction of thousands of homes in Mississippi and Louisiana. While engineered buildings fared reasonably well in the hurricane, semi-engineered buildings, including those constructed of light weight systems and non-reinforced masonry walls, sustained extensive damage [3].
Hurricane Andrew, a Category 4 hurricane, reportedly caused extensive damage to Dade County in Southern Florida of the United States. This event caused 15 deaths, tens of billions of dollars in damage and left a quarter of a million people temporarily homeless [4]. Contrary to this, many communities, which are primarily comprised of semi-engineered buildings, are known to have survived the effects of significant storms, including many observed by the primary author after major storms such as Hurricane Keith (2000) and Hurricane Iris (2001). In fact, many of the observed failures were limited to or were initiated in the roof systems of these buildings [5–7]. In these cases, the typical failure modes observed included the breakdown of connections and the loss of decking much more often than actual failure of the structural components themselves.

Construction methods and details
A limited range of semi-engineered building forms and types were observed in Belize. These structures are primarily located in urban settings and closely resemble engineered buildings in physical form. For the most part, the primary difference between engineered and semi-engineered residential buildings in this CGP 41251 area appears to be in construction detailing. While concrete slabs are used in some instances, primarily in the northern districts, most roof systems are made of timber trusses of sawn lumber bolted together at their joints and strapped to concrete roof beams or walls with bolts and mild steel hurricane straps. Timber purlins and battens are typically fastened to rafters with simple common nails, and span between trusses. In limited instances, however, metal connector clips are used. Roof decks are primarily of cold rolled steel sheets, which are either nailed or screwed to timber purlins. Figure 3 illustrates the details of a typical semi-engineered building roof system as observed in Belize.
The ranges of roof types, materials, and forms observed in Alibag and surrounding areas are also remarkably similar. Within the town of Alibag itself, there is a large number of non-engineered buildings, however, the specific area inspected, which sits directly on the coast, includes a remarkably high ratio of SEBS to NEBS. Also remarkable is the fact genetic maps the range of roof framing and roof cladding types are very limited, with un-trussed timber frames making up the majority of roof systems observed and Mangalore tiles making up the majority of roof decks utilized. Figure 4 illustrates typical roof construction details, as observed in Alibag, which are no different from observations made in other communities, such as Palghar in India.
Four types of roof deck were observed to constitute the majority of semi-engineered buildings in the areas surveyed in Belize and India. Figures 5–9 illustrate the various deck and fastener types utilized.
In Belize, details, such as material type, deck thickness and overlap of individual roof deck units, are usually similar to that of engineered-buildings. However, in semi-engineered buildings, there is often insufficient attention paid to more subtle details, such as faster embedment lengths and the spacing of fasteners in general roof areas and zones that typically attract higher wind velocities. The effects of some of these deficiencies are highlighted when estimated pressure levels are compared to the capacities of the various components.