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Building & Renovation Planning -- Sprinklers

Planning For Roof-Top Sprinklers

For those who are planning to build or revovate your building, this is the perfect time to give consideration to the inclusion of exterior roof-top sprinklers. However, first a clarification.

Types of Sprinkler Systems

  1. Interior - Commercial/Industrial
    This is the type of sprinklers that we are familiar with in stores, offices, factories and public buildings. You see them arranged in a regular pattern projecting through the ceiling or suspended just below the ceiling or building roof. They are contually armed and ready to release soaking amounts of water should a fire occur in the immediate vicinity. Activation occurs when the sprinkler head reaches a set temperature. Heads activate individually. These systems are regulated by building and fire codes. Their purpose is fire suppression -- to put a fire out!

  2. Interior - Residential
    The effectiveness of commercial fire sprinkler systems is now expanding focus into the residential area. In the coming years it will be mandated -- beginning with new construction and renovations. Exactly how it will be implemented remains to be seen, but you can expect it to become a requirement. If you have construction/renovation plans, be sure not to overlook this area. Your local building and fire authorities will be your best sources for information. Again, their purpose is fire suppression -- to put a fire out!

  3. Lawn & Landscape Irrigation
    These systems are popular in urban areas to keep lawns green and lush and landscape foliage appealing. These systems can be extensive and highly automated. They operate on the principle of slow-rate water distribution for the purpose of maintaining vegetation health. These systems are not for fire suppression. However, a properly irrigated landscape has a low fire risk.

  4. Exterior Roof-Top
    This concept is growing in popularity, thanks to the development of strategies by the Ontario Ministry Of Natural Resources. Recent experiences have proven that this technology is highly effective for protecting property from wildfire. Exterior sprinkler systems are totally separate from interior systems. Components, installation, water supply and operational considerations are quite different. The concept involves producing artificial rainfall that bathes the building and the landscape adjacent to the building. This is achieved by mounting commercial (agricultural) grade sprinklers at the highest point(s) of the building or on nearby poles, towers, trees, etc. These sprinkler use supply lines that route back to a common point at ground level where water is supplied at sufficient pressure and volume to support the sprinklers. Usually a gasoline powered fire pump drives the system. Electricity driven systems usually cannot provide the water required and are unreliable in fire situations. Often sprinklers are integrated with other exterior fire suppression strategies. Their purpose -- fire prevention -- reduces the ability of a fire getting established within the protection perimeter.

Sprinkler Installation

Roof-Top sprinklers are easiest to install during the construction phase. Every installation will have its own flavour dictated by building architecture, physical appearance tolerance and integration with other systems and fire protection strategies. The following are the key criteria for a successful install.

  • Sprinkler Placement
    Choose 1 or more high locations for sprinkler head placement. Typical heads have a 15-18 m. (50 - 60 ft) throw. Allow for some wind-drift and overlap, as well as overspray to the surroundings. Use a sufficient quantity of heads to ensure complete coverage. Spacing 50' apart is a good starting point.

  • Sprinkler Mount Points Each sprinkler head should project above the roof such that the spray shoots above nearby objects that would block proper distribution or be damaged by a continual water stream. Each head requires a 3/4" female pipe thread fitting pointing vertical. It should be securely fastened to the structure so as to accommodate the lateral forces when operational. Care must be taken to prevent water from wicking along supply lines into your building. Also, make sure that any water provided by this system cannot enter your building in any way.

  • Supply Lines Water supply lines will lead from each elevated sprinkler head to a connection point at ground level. Typically, this point will be on the outside of your building and conveniently located for the attachment of supply hose from a fire pump. It is critical that the network of supply lines be naturally draining. If your lines must be manually drained at the end of each season, trouble will await you in future years. Each sprinkler requires a minimum of a 3/4" supply line. In general, add 1/4" to line size for each head. When dealing with multiple heads, make sure that you include a valve to control water flow to each head. Supply lines will use standard plumbing materials. This may be metal or plastic -- just make sure that it can handle a minimum of 150 psi (300 psi is ideal). Operational pressure is usually 40-80 psi, but there will be pressure surges from time-to-time.

  • Water Supply For most installations, water will be supplied by a portable fire pump with a discharge line attached at the connection point. The pump will draw water from some nearby source such as a lake, pond, or even a large storage tank. When needed, the pump is started and the sprinklers activated. In the case of an active fire situation, both the sprinklers and a hand-held fire hose could be simultaneously made operational. For those who wish to integrate their household system for casual watering, care must be taken to prevent backfeeding that might contaminate the household water supply. Note that your household system would probably only support one high volume sprinkler at a time.

Final Words
          For those of you looking to construction or renovations, include roof-top sprinklers in your planning. If nothing else, at least include a rough-in. Cost, at this stage is minimal. Retrofits can become costly and may result in an undesireable visual impact.

View sprinkler installation Case Study #1
View sprinkler installation Case Study #2

Here is an excellent reference:

Wildfire Water Pumping and Sprinkler System Handbook, 3rd Edition

One Stop Fire Products Inc.
Markham, Ontario
L3P 7H9
Tel: (905) 946-1033