Terracotta and Cement Roofs Vulnerable in Wildfires, Study Finds

Share via AddThis
Posted on May 20, 2013

Although made of fire-resistant materials, terracotta and cement roof tiles are vulnerable to penetration by windblown embers generated in wildfires, according to new research findings from the National Institute of Standards and Technology (NIST).

In scoping experiments conducted in the Fire Research Wind Tunnel Facility at Japan’s Building Research Institute, NIST fire scientist Samuel Manzello found that the embers—or firebrands—infiltrated gaps between certain types of roofing tiles and, once trapped, proceeded to melt the underlayment below.

Of the four roof styles studied, the flat tile terracotta roofing assembly performed best probably due to its interlocking design. For these tiles, the firebrands were observed to become trapped within the interlocking sections of the tiles and, as a result, the firebrands did not penetrate past the tiles towards the underlayment.

Manzello cautions, however, against a false sense of security with this type of roofing assembly.

“Over time, gaps can develop in roofing assemblies due to settling of the structure, aging of the materials, earthquakes or other causes,” he says. In an earlier study, Manzello and colleagues simulated this effect and observed greatly reduced performance of ceramic roofing assemblies as compared to well-aligned Spanish tile roofing assemblies.

This infiltration of embers through gaps, he explains, ultimately could lead to ignition of materials in an attic space immediately below.

The research findings suggest that one potential approach to reducing wildfire risks would be to install continuous, fire-resistant underlayments. This hypothesis, Manzello says, requires further investigation.

In the new research, Manzello studied roof assemblies made of flat and profiled (wave-like) cement and terracotta tiles. The assemblies were exposed to firebrand showers generated by the NIST-developed firebrand generator. Devised by Manzello, the generator, or NIST Dragon, is a two-meter tall, goose-neck-shaped apparatus that breathes in wood chips and exhales firebrands at a controlled rate. The novel device supports NIST’s program to improve the fire-resistance or hardening of structures in the wildland-urban interface (WUI), with the ultimate aim of reducing property damage and the threat to life safety associated with WUI fires.

Source: NIST



40,196 science & technology articles

Categories

Our Articles (see all)

General News

Follow us

Facebook   Twitter   Pinterest   StumbleUpon   Plurk
Google+   Tumblr   Delicious   RSS   Newsletter via Email

Featured Video (see all)

Dark matter can be observed by analyzing distribution of regular matter and its gravitational interactions in large-scale objets, such as galaxies. Image source: YouTube screenshot.
Complex dark matter
In this video, U.S. CMS Education and Outreach Coordinator Don Lincoln discusses how dark matter might have a…

Featured Image (see all)


Multi-Utility Technology Testbed Aircraft On the Runway
The X-56A Multi-Utility Technology Testbed (MUTT) is greeted on an Edwards Air Force Base runway by a U.S.…