Flooding

The impacts of a changing climate include an increase in the frequency, intensity and duration of heavy precipitation and storms. Climate change is also leading to a rise in sea levels; a table has been produced by the Intergovernmental Panel on Climate Change to provide a cautious estimate of these rises.

As a result:

• Buildings that suffer storm damage will require more repair and maintenance work.
• Vulnerable buildings will face an increased risk of flooding. Affected buildings will require extensive repair.
• Rain penetration problems will increase. Affected buildings will require repair and, where possible, corrective action.
• The predicted sea level rise and storm surges will have catastrophic consequences for buildings in vulnerable locations.
• Furthermore, with parched soils, increased paved areas and development in inappropriate areas more flooding will occur.

Flood resistance

Concrete is not damaged by water. Concrete submerged in water absorbs very small amounts of water over long periods of time, and the concrete is not damaged. In flood-damaged areas, concrete buildings are often salvageable.

In the rebuilding of New Orleans after Hurricane Katrina, architects and engineers are looking at structures that will keep water out and not shift or float away when submerged in floodwaters. One solution is reinforced concrete walls to the roof height with a 12-inch-thick concrete slab. In one example, the slab will be kept in place with 8-inch helical anchors drilled 10 to 13 feet into the ground (Architect Hank Browne and engineers DMK Group, Building Design and Construction, April 2006).

Concrete will only contribute to moisture problems in buildings if it is enclosed in a system that traps moisture between the concrete and other building materials. For instance, a vinyl wall covering in hot and humid climates will act as a vapour retarder and moisture can get trapped between the concrete and the wall covering.