Fireplaces & Chimneys. Are You Proactive or Over-reactive?

The I-ENG-A Report from Investigative Engineers Association, Inc

On Saturday, November 18, 2000, at 8:45 p.m. the smoke detection alarms at a well-known hotel chain location sounded. Around the same time flames were seen on the exterior of the hotel’s fifth and sixth floors. When the fire spread through the eaves and erupted on the building’s exterior, the sprinklers activated but the water didn’t reach the flames. The fire burned for six hours and destroyed 126 of the 350 rooms and consumed exterior balconies and siding on the fifth and sixth floors. Damage was estimated at $19 million. No one was injured.

The fire started in the vent shaft of a wood-burning fireplace in room 220 and crept up the flue and ignited interior supports of the roof overhang. Federal fire experts estimated it smoldered undetected for three hours before erupting. Although all the responsible parties may never be identified, the cause of the fire was determined to be defective installation.

Recently, many units are being converted to gas burning fireplaces. Over the last couple of decades tens of thousands of these conversions have taken place. There are a number of positive benefits to using gas fireplaces. They include: reduced emissions into the atmosphere resulting in improved air quality, reduced operating costs and lower maintenance costs (including property management and fireplace and chimney care).

During the glory days of wood burning it was not uncommon for local fire departments to respond to fifteen or twenty chimney fires in a single season. Today, they are lucky to have less chimney fires due to benefits of gas fireplaces.

It is not our goal to deter anyone from converting to gas burning fireplaces. It is important, however, to have all the facts before making what can be a sizable investment.

Considerations before converting to gas include: conversion costs and the lost aesthetic value of a wood?burning fireplace. A wood?burning fireplace adds value to the property; both in terms of appraised value and appeal as a rental unit. If you have been told that your fireplace chimneys are unsafe and should be replaced it might be prudent to get a second opinion. Don’t hastily make the decision to give up a valuable feature of your property that you may never get back. After all, fireplaces have been around for hundreds of years and routinely and safely serve our needs.

Some instinctual reactions to the hotel fire include keeping combustible material such as magazines, newspapers, and decorative objects away from the opening of the fireplace. One elusive spark coming to rest in the wrong spot could be the end of a good evening.

Also important is how the fire is started in the fireplace. Chimneys and fireplaces need to be warmed up slowly. Rapid temperature changes in the unit may cause serious damage. As heat is produced inside of the unit, the fireplace components start to expand with the exterior of the chimney still cool. If the interior is heated too rapidly, it will fracture and split. This can allow the products of combustion to enter the chimney chase. This damage usually occurs from three different scenarios.

[ This photo displays a significant crack in the second flue from the inside top of a chimney which, if not fixed, can present a risk for fire. ]

The first is the person who stuffs newspapers and cardboard into the fireplace, places wood on the pile and then ignites it. In no time the temperature in the fireplace rises from a room temperature near 70�F to over 600�F. The next scenario is Christmas morning. The presents are opened and the wrapping paper is stuffed into the firebox. One properly placed match and 20 minutes of cleanup is averted. Once again the chimney is heated dramatically and flue tiles split and separate. The third scenario concerns a creosote-fed chimney fire. Creosote is a byproduct associated with burning wood. Smoke cools and adheres to the cooler walls of the chimney. This, if allowed to build up will thicken to the point that it covers the walls of the smoke chamber and chimney. One hot spark or a flame that is allowed to rise into the damper area may ignite this material. The result is a rapid fire that burns out all of the material stuck inside of the chimney. Temperatures from this event have been measured at over 2000�F, more than enough to destroy your chimney, liner, and possibly your home. All of these scenarios may be averted with proper knowledge and maintenance.

NOTE: This article was published by the Investigative Engineers Association (I-ENG-A) and written by a member firm, Professional Investigative Engineers, Colorado. I-ENG-A is a national network of independent engineering firms across Canada, the United States and Carribean who are committed to providing the insurance industry and litigation professionals cost-effective and timely reporting. For details, please visit or or call toll-free (800) 523-3680 for the profile of the firm nearest you.