TT Talk - Winter Preparations
As the northern hemisphere enters the winter months, it is timely perhaps to remind that a cold weather maintenance plan is important for facilities located in all but tropical areas
The following is advice gleaned from the TT Club's preferred supplier of risk assessment surveys, Global Asset Protection Services LLC.
Such plans should include:
- Ensuring that vents and roof penetrations, such as skylights, are maintained and weather tight, and access points to monitor or clear excessive snow accumulation are checked.
- Examining and maintaining heating systems to correct any deficiencies before the extreme cold arrives. It is generally recommended that temperatures should be maintained above 4 degrees centigrade (40 degrees Fahrenheit) - subject to specific use of your facility - and adequate fuel reserves should be on hand at all times.
- Preparing and monitoring fire protection systems during cold weather. Valves and hydrants must be accessible, dry pipe sprinkler systems should be purged of moisture, and systems should be checked for leaks.
Roof collapse due to snow loading is a concern in both northerly areas accustomed to snow, and more temperate areas where snowfall may only be rare
. Factors such as age of the roof, design criteria, and equipment that has been added subsequent to design may not be known to site personnel. Long-span, light-metal roofs typically used for warehouses can be particularly vulnerable to snow loading. For this reason, it is important to consider how to avoid accumulation of snow on roof areas. Below are some items to consider for roof snow loading/removal. This is not exhaustive, just some brief guidelines.
- Personnel safety is critical when inspecting a roof for snow build up. Site safety program for proximity to building/roof edge must be adhered to at all times. Personnel on a snow covered roof must be aware of the locations of any skylights or other areas where they may trip or fall through. No one should go on the roof alone.
- 'Sticking' the depth of the snow on the roof is a common method. A predetermined amount should be used to trigger removal. This should be based on design of roof. If unknown, 6-8 inch (15-20 cm) accumulation is a common amount in areas that are not used to having much snow. Areas accustomed to heavy snowfall typically have roofs designed to handle an increased loading.
- Site personnel need to be aware that heat loss from the building through the roof will form ice that is MUCH heavier. Therefore, 'sticking' the depth alone is not good enough. Particular worries for ice build up are located over specific heat sources (such as boilers) and penetrations through the roof for stacks, vents, etc. Ice should be carefully removed. Chemically melting the ice should be reviewed by site environmental personnel.
- Removing of snow must be cautious. Preferably using plastic hand shovels, taking care not to damage/penetrate the roof exterior nor remove loose stone from the roof ballast.
- Snow removed and thrown to the ground needs to be carried out with caution, particularly to avoid potential ice chunks hitting windows, cars, transformers, etc.
- If necessary, snow blowers/brooms can be used on the roof but at no time should gasoline be stored on the roof. All equipment should be removed from roof after use including shovels, tarps, etc.
- Differing roof heights with a sloping collection of snow should be cleared even if the rest of the roof is free of accumulation.
- When removing the snow, do not create piles on the roof as this concentrates weight. Evenly remove as much as possible.
- Personnel should be educated to recognise a deflecting roof. Symptoms include:
- Lights hanging lower than normal and often getting hit by inside permanent mounted crane
- Lights flickering on and off due to wires being stretched
- Water infiltration at the roof where it connects to walls
- Creaking noises
- Peeling/falling paint from underside of roof deck
- Other utilities having minor interruptions - water pipes that are attached to the roof breaking or leaking
- Broken bolts/screws that normally hold the roof together found on the floor
- Roof drains that become raised above the roof deck
Be prepared this winter!