Minimizing flood and water damage from hurricanes and extreme weather events
Extreme spring and summer rainfalls across the USA and Canada have far exceeded the annual averages. In the central and eastern parts of the continent, heavy rainfall and flooding have caused millions of dollars in damage, lost revenues, damaged crops and homes. As we all know, Hurricane Harvey ravaged southern Texas and the nation’s fourth largest city, Houston, flooding vast areas of the region and Hurricane Irma has pounded Florida, Puerto Rico and much of the Caribbean with high winds and downpour. Hurricane Jose is hot on Hurricane Irma's heels in causing additional potential damage. In British Columbia, the threat of heavy rainfalls in fall is anticipated after a tough spell of raging wild fires over the summer.
Water ingress resulting from storm surges, high rainfalls and flooding can cause massive damage to the typical home. When water ingress occurs from extreme weather events, it becomes necessary to assess the extent of damage and contamination, clean up removal requirements and how to re-construct or repair to mitigate the probability of similar damage in the future.
When seeking methods to reduce the risk of water ingress, spray foam insulation is often overlooked as a comprehensive solution that can help play a role to keep out moisture and deter flood damage. However, spray foam insulation can be a key component in the design of building assemblies against future disaster-driven damage. Both open-cell and closed-cell spray foam insulation can be used throughout a residential or commercial structure to manage and minimize moisture ingress.
When it comes to addressing moisture, open-cell foam is better suited for use against building materials that can be damaged by water build-up. When applied against these types of materials (i.e. exterior wood sheathing), particularly in hot/humid climates, insulation should allow moisture diffusion to occur, just enough to let adjacent building materials breathe in order to prevent moisture entrapment. Open-cell foam delivers this ‘breathability’ and allows building materials to dry, minimizing moisture build-up and related problems such as mold. For example, in scenarios where the foam is applied to the underside of a roof deck, in the event of a roof leak, water drains straight through the insulation by gravity rather than being trapped against the roof sheathing where it could contribute to roof rot. Upon drying, some open-cell spray foam insulation products return to their original state without warping or distortion, and the effectiveness of the insulation is restored back to its original performance potential.
The Federal Emergency Management Agency (FEMA) has identified closed-cell spray foam as a flood resistant material due to its resilience and strength. According to the government agency, flood-resistant material is any building material capable of withstanding direct and prolonged contact with floodwaters without sustaining significant damage. Closed-cell spray foam, like Icynene ProSeal, can be used as a water-resistant barrier to help deflect moisture away while also helping to provide additional ‘racking’ strength to help resist the high winds of a storm or hurricane.
Dealing with the aftermath of flooding
When assessing flood damage, one must almost always assume that the water contains contaminants such as decaying organic matter and debris, raw sewage, fuel, solvents, microbes and mold. Through wicking, moisture and contaminants can be drawn up into areas above the actual flood level. Even after clean-up, homeowners may still notice problems with housing elements, since mold and other contaminants can be present due to wicking and therefore may render homes unliveable.
Cleaning up after a flood should involve an assessment of the extent of removals required, necessary cleaning, drying and disinfecting of surfaces by a qualified contractor. Proper cleaning drying and disinfecting of some porous materials may take days or even weeks to carry out. Mold can begin to thrive in as little as 48 hours when contaminated water floods an assembly. This makes it likely that many porous materials will, in fact, require removal following water ingress from an extreme weather event such as flooding.
Repair work following water ingress or flooding will often involve raising older buildings and constructing new buildings on piers or platforms above the Base Flood Elevation (BFE) and ensuring that construction below the BFE is done with flood-resistant materials. As a flood resistant material, closed cell spray foam insulation is suitable for application below the BFE.
Above the BFE both open cell and closed cell spray foams can be used but consideration has to be given to avoiding other porous materials that can absorb contaminated water. The choice of materials should be made based on sound building science principles. For instance, in a floor above a damp crawlspace it may be desirable to use closed cell foam because of its vapor retarding, compressive strength and water resistant characteristics. A qualified and experienced insulation contractor is able to help work through the best approach in repairing and protecting the structure from water ingress.
Building materials exposed to flooding must be resilient enough to sustain a certain amount of water exposure in order to avoid the need for complete replacement. A ‘repair and prepare’ approach using spray foam insulation can help reduce the risk of water ingress and potential damage as weather patterns across North America continue to change and challenge our approach in designing and building sound and solid structures to live, work and play in.