Is it risky to build “upwards not outwards”?

Thetford could experiment with allowing three- or four-story buildings in village centers by changing their zoning bylaws.

Is it risky to build “upwards not outwards”?
Demonstration of firefighting ground ladders of different heights; Photo credit: Mark Van Der Fyst. Left: if unobstructed, a 14 ft ladder reaches a second-story window; Middle: if unobstructed, a 25-ft ladder reaches a third-story window; Right: if unobstructed, a 35-ft ladder reaches a fourth-story window.

To add more housing in Thetford without contributing to rural sprawl is challenging. State and regional planning goals stress the importance of “the traditional pattern of development so as to maintain the historic settlement pattern of compact village and urban centers separated by rural countryside.”

However, the edges of Thetford’s villages are often constrained by important agricultural soils, steep valley sides, or wetlands. It seems that if we can’t readily build outwards, building upwards could be a solution to providing more housing. The recently passed HOME Act  (S100) permits “any affordable housing development … to exceed density limitations … by an additional 40 percent, which shall include exceeding maximum height limitations by one floor, provided that the structure complies with the Vermont Fire and Building Safety Code.” Unfortunately it doesn’t apply to Thetford because it only concerns “any area served by municipal sewer and water infrastructure.”  It does not extend to villages that rely on wells and septic systems.

Like other communities, Thetford has a building height maximum of 35 feet as specified in the Town’s zoning bylaws. Could we still build upwards in Thetford, at least in village centers? The prevailing answer is no, and it’s attributed to fire safety. The constraint, apparently, is that Thetford doesn’t have the equipment, specifically a ladder truck, to fight a structure fire in a building taller than 35 feet.

However, Thetford does benefit from mutual aid from other fire departments, and both Hanover and Lebanon have ladder trucks for those rare instances of a structure fire. Lebanon’s ladder truck can reach nine stories — the tallest sections of the Dartmouth-Hitchcock Medical Center. But very large trucks are hard to maneuver, especially down rural gravel roads. Village centers might be the only reasonable place where a truck this size could safely operate.

The smallest ladder trucks on the market today reach 50 feet, an advance over 35 feet, although all of that length may not be deployed vertically. Firefighters understand that “the top of the ladder drops one foot for every four feet the base is pulled away from the building.” Depending on where a truck can be positioned in relation to a structure, that 50-foot ladder may not reach to 50 feet in height.

To add an option, there are ladders without trucks (ground ladders). In choosing a ladder, firefighters consider these numbers: average height between two floors in a residential building is 10 feet; average height from floor to windowsill is three feet. Thus, a 14-foot ladder under optimal conditions can reach a second-story window from the ground, as it will be, on average, 13 feet from the ground. A 24-foot ladder can reach a third-story window, and a 35-foot ground ladder can reach a fourth-story window. (Indeed some ladders are marked for easy reference thus: a 24-foot ground ladder has the numbers “2” and “4” and in between those two numbers is the number “3”. So, that means a 24-foot ground ladder can reach a third story window. A 35-foot two section ground ladder has the numbers “3” and “5” with the number “4” in between them. That means a 35-foot, two-section ground ladder can reach a fourth story window). Three or four firefighters can handle a 35-ft ladder to access a fourth-story window, assuming there are enough volunteer firefighters.

However, former Thetford Fire Chief Don Fifield points out, “While a 35-foot ground ladder will reach a fourth-floor window under optimal conditions ( e.g. no obstacles like bushes or other objects making it difficult to minimize the angle and maximize the height of the side opposite the hypotenuse), it’s not the safest way to perform a rescue or to deliver water when you’re talking about a fourth-story situation. A ladder truck is preferred for safety and efficiency.”

Today there are around 50% fewer house fires than 40 years ago, although the average cost of damage has nearly doubled. The commonly used half-inch sheetrock has a fire rating of 30 minutes, while 5/8 inch “fire code” sheetrock has a rating of one hour. Fire codes have contributed to making structure fires less common. For instance, the VT Fire Code states “In new buildings three stories or greater in height, a quality assurance program for the installation of devices and systems installed to protect penetration and joints shall be prepared and monitored by the Registered Design Professional responsible.” Today in Vermont, buildings of three or more stories also require an external fire escape and multiple egress points. In addition, buildings over three stories, or having five or more units, require sprinkler systems. This sprinkler system must be able to work offline when power to the building is cut in the event of a fire. This becomes very difficult in communities without public water. A sprinkler system fed by a private well would require a large reservoir, pumps, and a backup power source.

Does this mean a building over 35 feet is a fire risk if built in Thetford? Not necessarily. But building a structure above three stories would incur a lot of additional cost to meet fire code. Thetford could experiment with allowing three- or four-story buildings in village centers by changing their zoning bylaws. It might lead to some in-fill development, as called for in the Town Plan. Or at the very least, it would reflect a better understanding of modern firefighting and building standards available to us today.

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