Upgraded Cement Block Walls
Reinforced cement block walls offer significantly more protection from hurricanes than un-reinforced walls although in varying degrees and at an escalating higher cost. Placing rebar in the walls at 2 to 3 ft vertical intervals and filling these holes with rebar increased the ability of the wall to hold together in category 2 hurricanes. Adding horizontal rebar adds additional strength. The next increment of protection and cost would be filling the entire wall with grout mix to survive category 3 hurricanes. This increased expense and can be difficult because of the tight space inside the block usually leading to an upsizing of the block specification to a minimum of 6″ deep and ideally 8″ deep. This adds significant block, rebar and concrete costs to the project but result in walls that can withstand category 3, 4 and even 5 storms if all these upgrades are included in the design.
Concrete block walls can be made to survive hurricane forces but are inherently energy in-efficient. Heat moved to cold through concrete and can result in significantly higher utility costs in hot, cold and mixed climates. To offset this inefficiency, mechanical systems have to be upsized and work harder using more energy and incurring higher operating expenses.
To improve the energy efficiency of concrete block wall, insulation must be attached to the concrete surfaces to stop the transfer of hot to cold. This process adds expense and can reduce interior living space if not planned for initially in the sizing of the home footprint.
Attaching interior and exterior surfaces like clapboards, drywall and cabinetry will require additional planning, methods and expense in the form of attachment strips to the concrete walls made of metal or wood that allow places to fasten material. All these viable should be designed into the project and the additional costs of material and labor analyzed to understand the trade-offs of different methods of achieving the preferred end goal of hurricane survivability combined with energy efficiency and a comfort living environment.