Sprinkler systems are proven to control fires and minimise damage. Developments in technology mean that home sprinkler systems can be a viable addition to homes of all ages, as this example of a system designed for an 1891 villa demonstrates.
The owner of the villa built in 1891 had been keen for some time to install a fire sprinkler system to help preserve the 2-storey native timber family homestead.
The proposed home sprinkler design involved a ring main installed in the exterior wall of the ground floor with horizontal side wall sprinkler heads protruding into each room through the wall linings. The accessible roof space enabled another ring main with dome sprinkler heads to be located more centrally in every upstairs room (see Figure 1).
However, the homeowner preferred the look of the dome sprinkler heads and, being a builder by trade and understanding how the house was built, decided dome sprinklers could be installed throughout and also protect the roof space.
A sprinkler system was designed and calculations for the hydraulics of the system prepared for a building consent. Horowhenua District Council permitted the connection of a 50 mm pressure pipe to the town supply water main. Water travels 120 m to the house, through a flow switch and non-return valve (connected to a monitored alarm system). This reduces to a 32 mm pipe under the house and up the east and west walls to the first floor. A product was chosen for its low material costs, ease of installation, fire rating and access to a certified fabricator.
Installation in one piece
Scaffolding was set up on the east and west sides of the house to carefully remove two rows of matai 9 inch rusticated weatherboard at first floor level. This exposed 10 × 2 inch floor joists at 18 inch centres with an unobstructed view from one side of the house to the other, except where the chimney and staircase are sited. This enabled the change from wall mounted to ceiling mounted sprinkler heads.
The exact position of the sprinkler heads was decided based on where they were needed in the ground floor rooms and a little adjustment for the position of ceiling/floor joists between floors. Then, 8 × 1 inch totara boards were made to straddle the required positions of each head.
These boards were then prefitted and drilled for the sprinkler head size and marked at the outside ends. Removed, the boards were laid out on the ground and the piping/sockets were cut/welded and clamped into position ready for installation in one piece. These slid through between the floor joists and were repositioned above the holes previously drilled in the ceiling.
The clamps hold the piping so that the sprinkler heads could be screwed into place. Four screws around each sprinkler head hold the boards in position and disappear under the sprinkler head cover dome. This system allows for easy removal if repairs or adjustments need to be made.
Less pressure on water
A template was made for drilling holes at the outer ends of the floor joists for the north/south piping halfway up the floor joist. This was to make room for a welding iron and to miss the 4 × 2 inch framing of the top storey (which is tenoned and mortised into a 5 × 3 inch top plate of the bottom storey framing, also with the 10 × 2 floor joist sitting on top). This proximity allowed the vertical pipes to be fed up inside the walls on the east/west sides – ‘looping’ the system under and around the house and increasing the directional flows of water.
Installation of an attic ladder enabled good access to the ceiling and roof space.
Progress in this area was much easier as the rafters started at the outside end of the 14 inch soffit and two posts supported the hipped roof (with no collar ties, trusses or ceiling joist beams to contend with). Two back rooms on the second storey were accessed by the board method as these had skillion roofs. It was decided to cover the roof space area with sprinkler heads just below the ridge with a loop pipe around this area (a total water rise of 8.5 m above ground level). From here, a 25 mm pipe returns to the ground floor toilet and a fresh supply of water is recharging the system each time the cistern is flushed.
The final specifications included:
- first storey – 10 dome sprinkler heads
- second storey – 8 dome sprinkler heads
- attic – 8 pendant heads
- 500 kPa pressure at sprinkler heads
- flow test of 90 litres per minute achieved (manufacturer flow tests recommended 54 litres per minute)
- 170 m of pipe used.
Problems encountered during the installation were largely due to access limitations. There was little or no room under the ground floor for the loop pipe under the house, which led to excavation of a tunnel. Access to the attic also proved awkward until an attic ladder was installed. There was minimal disruption and disturbance to the rest of the house.
The benefits far outweigh the effort required. The homeowner can now look at the scrim covered walls – liable to take only a few seconds to ignite – knowing that 90 litres of water per minute would be spraying around the room in the event of a fire.
Articles are correct at the time of publication but may have since become outdated.