Task force calls for sprinklers in new homes
Sprinklers are effective, but what about the fire resistance of the house structure itself?
February 6, 2018 by John Bleasby
A recommendation that mandatory sprinkler systems be included in the building code as early as 2020 was recently submitted to the National Building Code of Canada commission by a task force assembled by the Canadian Commission on Building and Fire Codes. That sounds like an expensive proposition, although not according to the Canadian Automatic Sprinkler Association. Not surprisingly, they reportedly downplay the added costs, saying sprinklers would add a mere 1.0 to 1.5 per cent to the cost of a new home. Far more expensive, of course, would be adding a sprinkler system to an existing home, given the amount of plumbing that would be installed behind existing walls and ceilings.
Today’s homes burn faster
A study conducted by Underwriters Laboratory in the U.S. recently reported in the Washington Post concludes that homes burn significantly faster today than homes of the past. In fact, the study indicates that occupants often have less than three minutes to evacuate versus some 17 minutes three decades ago. “Most people underestimate the speed and power of fire and smoke,” according to the National Fire Protection Association. Their advice to homeowners: “You shouldn’t fumble with the fire extinguisher, grab your photo albums or even rescue your cat. GET OUT!”
What is causing homes to burn faster?
Instead of jumping on the home sprinkler bandwagon, perhaps it would be a good idea to look at why homes are burning faster. Initial causes of fires haven’t changed much over the past 100 years —mostly human factors such as candles left burning at night, smoking in bed, flammable liquids stored near heat and electrical deficiencies of various sorts. However, once started, fires spread quickly, and that is the issue. The culprits seem to be two things: Home design and construction, and the amount of fast-burning synthetics used in furnishings.
Open floor plans are said to contribute to the speed at which flames spread; the more oxygen available, the faster the fire will grow. The smaller rooms of older designs could be shut off with doors. However, today let’s face it — open floor plans are here to stay, and home furnishing selections will always be the domain of the client. On the other hand, materials used in home construction can have a positive impact on the fire resistance qualities of the structure itself.
Concrete and brick
Concrete and concrete blocks don’t burn. While that seems obvious, builders might still want to do some research about the products they use. Concrete is an aggregate, from 60 to 80 per cent of the volume, and can vary in its ability to withstand heat without losing load bearing capabilities — moisture in the aggregate can expand when heated, causing concrete to sinter after long exposure. A brick wall has the potential to offer from one to four hour fire resistance, while a one-inch layer of stucco can add another hour.
ICF’s offer recognized fire retardation qualities
While poured concrete and concrete block is very popular for foundation and basement walls, fire resistance drops above grade due to traditional stick frame construction methods that turn homes into tinder boxes. However, by going right to the roof, ICF’s (Insulated Concrete Forms) offer new home clients the possibility of having an all-concrete building envelope. While focus is often placed on the high levels of insulation and thermal break qualities of ICF, its fire resistance should not be overlooked. In fact, this author’s home is 100 per cent ICF, resulting in a 10 per cent discount on the home insurance policy.
Composite lumber’s superiority over dimensional lumber
When it comes to post and beam load bearing elements, composite lumber products such as CLT’s (Cross Laminated Timber), LSL’s (Laminated Strand Lumber) and PSL’s (Parallel Strand Lumber) are also highly fire resistant, making them a rival for steel and heavy timber.
For example, according to FireEngineering.com, CLT’s have “excellent fire resistance, comparable to that of non-combustible materials and to heavy timber (Type IV) construction, due to the ability of thick wood assemblies to char slowly at a predictable rate while maintaining most of their strength during the exposure.”
Even CLT panels, used for flooring and walls are similarly recognised. “After testing CLT panels to the standard fire resistance test (CAN/ULC S101 (Canada), ASTM E119 (USA), and ISO 834 in other countries), manufacturers propose that a five-layer CLT floor panel can receive a 1.5-hour rating; and a three-layer wall panel can receive a 45-minute rating,” the publication continues. “This fire resistance is based upon the insulating properties of the char layer that develops during the exposure to the fire.”
In other words, composite lumber gives firefighters more time to save a building from collapse or room-to-room destruction, and potentially give more time for occupants to evacuate safely.
Interior elements all have an impact
Fire-resistant gypsum board, names as Type X and Brand Firecode, is available. The paper layer burns slowly, and its non-combustible core contains chemically-combined water that comes out as steam, impeding the transfer of heat. Multiple layers of gypsum can be used to add even more fire resistance to a room or an entire building. Combine fire-rated gypsum with steel studs instead of wood studs, and you have added significant fire resistance to the wall structure.
Insulation choices can add to fire resistance of a wall structure too. For example, mineral wool insulation has better heat resistance quality than fibreglass and will not melt at temperatures as high as 1800° F. Blown cellulose, if treated with nontoxic fire-retardant additives such as boric acid, will withstand temperatures up to 1200° while also filling gaps around electrical boxes and framing left by batt insulation, thus hindering the spread of fire.
Alternatives to a water-fed sprinkler system
There are also alternatives on the market to the traditional water–fed sprinkler system. The Canadian invention Haven (see previous coverage) is an excellent solution for home fire protection, combining the best characteristics of detectors and extinguishers without the short-comings of either. The Haven detects heat, not smoke, so there are fewer false alarms when, for example, the toast burns. The unit shoots out five pounds of non-toxic powder at high-pressure to supress the source of the flames, much like a hand-operated extinguisher, yet maintaining visibility that allows occupants to focus on evacuating quickly.
Will mandatory sprinkler systems find their way into Canada’s building codes in a couple of years? That depends how home builders respond to the lobbying efforts of fire prevention groups. In the meantime, there are materials and products contractors can offer clients today that can limit fire damage and, most importantly, give occupants more time to get out safely.
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