Roof Weight With Ice and Snow

The following is an excerpt from the article “Preventing Roof Collapse on Homes.” For more information please visit disastersafety.org.

ESTIMATE HOW MUCH THE SNOW ON YOUR ROOF WEIGHS USING THESE GUIDELINES FROM IBHS:

Fresh snow: 10-12 in. of new snow is equal to one in. of water, or about 5 lbs per square foot of roof space, so you could have up to 4 ft. of new snow before the roof will become stressed.

Packed snow: 3-5 in. of old snow is equal to one inch of water, or about 5 lbs per square foot of roof space, so anything more than 2 ft. of old snow could be too much for your roof to handle.

Total accumulated weight: two ft. of old snow and two ft. of new snow could weigh as much as 60 lbs per square foot of roof space, which is beyond the typical snow load capacity of most roofs.

Ice: one in. of ice equals one ft. of fresh snow.

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Ice Dams and Flat, Monoslope, Low-Sloped Roofs

The following is an excerpt from the article “Preventing Ice Dams on Businesses.” For more information please visit disastersafety.org.

FOR FLAT, MONOSLOPE, LOW SLOPED ROOF SYSTEMS:

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  • Commercial buildings with flat roofs are particularly vulnerable to water leaks if
    ice dams keep water from flowing into roof drains.
  • If the building has a history of ice dams, removing the snow will remove the source of a potential ice dam.
  • A heavy duty push broom with stiff bristles may be used to brush off the snow on low slope or flat roofs. A shovel or snow blower should not be used since they may tear up the roof cover system.
  • Ice dams don’t actually have to clog the drains and in fact the drains are frequently clear and open. The ice forms a ring around the drain and sometimes a dome over the drain that keeps water from flowing.
  • If ice dams form around the drains, heating cables can be connected to the drains to prevent ice buildup.
  • Heating cables can be installed in a zig zag manner in gutters.
  • Heating cables can also be placed on the roof, connecting them to the drainage system so a path is created for the melting ice to follow.
  • If there is extensive ice build-up around the drains, consult a roof contractor to ensure that the roof cover system is adequately sloped to the drains.
  • When the roof is dry, inspect the roof cover for evidence of long term standing water. This will be evident by the presence of mold, mildew, and even small vegetation growing. This indicates a problem with the slope of the roof cover system; which will reduce proper water shed and drainage. The roof cover system can likely be re-pitched with additional insulation boards by a roof contractor.
  • In low sloped roof buildings, the space above a suspended ceiling located below the roof may be heated and cooled like the occupied area below. If that is the case, there is no need to insulate above the suspended ceiling or seal the ceiling’s penetrations.

 

Estimate How Much Weight Your Roof Can Support

The following is an excerpt from the article “Preventing Roof Collapse on Homes.” For more information please visit disastersafety.org.

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ESTIMATE HOW MUCH WEIGHT YOUR ROOF CAN SUPPORT
  • Unless the roof structure is damaged or decayed, most residential roofs regardless of the location of the house should be able to support 20 lbs per square foot of snow before they become stressed.
  • In some areas of New England and in mountainous areas throughout the United States, snow loads used in home design may be considerably higher and the roofs may be able to resist a greater depth of snow.
  • If you live in an area known for lots of snow, you can probably check with your building department to find out if higher loads were used at the time your home was built.

Steep Roofs and Ice Dams

The following is an excerpt from the article “Preventing Ice Dams on Businesses.” For more information please visit disastersafety.org.

snowy_roof_smFOR STEEP SLOPED ROOF SYSTEMS:

  • If the building has a history of ice dams, removing the snow will remove the source of a potential ice dam.
  • A roof rake may be used for most single story buildings while remaining on the ground to pull snow down the roof slope.
  • Do not pull snow back against the slope or sideways since the snow may get underneath the cover and can break shingles.

For buildings with a history of ice dams with roofs that cannot be reached with a roof rake from the ground, consult a roofing contractor. Occupational Safety and Health Association (OSHA) regulations and standards should always be followed when working on a roof. Fall protection should always be implemented when working on a roof.

Remove or relocate heat sources that are installed in open areas directly under the roof, such as an attic or mechanical room. A warm attic melts snow on the roof, causing water to run down and refreeze at the roof’s edge where it’s cooler.

INCREASE VENTILATION IN ATTIC SPACES.

  • Soffit/ridge vents provide good ventilation for gable roof systems, however due to retrofit costs they are not always a practical solution for existing roofs.
  • Gable end vents are not quite as effective as soffit/ridge venting, however they are cost effective.
  • Electric fans can placed over the gable end vents to increase the flow of air. Box or static vents are practical improvements for hip roofs.
  • Recessed light fixtures in the ceiling below the open area that is directly under a roof, such as attic space, should be insulated to prevent the release of heat into the attic.
  • Check to see if there is any visible light from recessed light fixtures in the attic. If there is visible light, they are not adequately sealed or insulated.
  • Insulate or seal all attic penetrations such as partition walls, vents, plumbing stacks, electric and mechanical chases, and access doors.
  • If the roof covering is going to be replaced in the near future, ensure that a sealed roof deck is installed using at least two layers of underlayment cemented together or a self-adhering polymer modified bitumen sheet (similar to underlayment).
  • The sealed roof deck should extend from the edge of the eaves to at least 24 inches beyond the inside of the exterior wall. See Sealing the Roof Deck

Prevent Roof Collapse on Homes

The following is an excerpt from the article “Preventing Roof Collapse on Homes.” For more information please visit disastersafety.org.

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Guidance for understanding how much snow is too much for your home’s roof to handle.

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EVALUATE YOUR RISK OF ROOF TOP SNOW/ICE ACCUMULATION

  • Melting snow tends to more quickly run off of steep sloped roofs with slopes greater than 3 in. of slope in 12 in. of horizontal distance, particularly the steeper ones that are typically found on houses in northern climates.
  • Ice and snow tend to more readily accumulate on low slope and flat roofs over porches, lanais or parts of a home that are next to a taller section of the house, especially during high winds.

Preventing Ice Dams

The following is an excerpt from the article “Preventing Ice Dams on Businesses.” For more information please visit disastersafety.org.

To help prevent ice dams from forming:

white_contractor_iinstalling_insullationIncrease insulation above ceilings. If the ceilings are suspended non combustible mineral fiber, then install fiber glass
batt insulation. If the ceilings are drywall nailed directly to wood joists, blown insulation or fiber glass batt insulation can be added. When adding fiber glass batt insulation, if there is a paper facer, place the paper side facing down.

Create a roof preventative maintenance plan that includes periodically inspecting the roof drainage system for proper flow including drains, scuppers, gutters, and down spouts.

Self regulating heating cables can be permanently installed on gutters, downspouts, and around roof drains. Since their power is self adjusting based on the ambient temperature, they are cost effective.

The American Society of Heating, Refrigerating, and Air-Conditioning, Engineers (ASHRAE) can be a valuable resource for guidance on the use of heating cables.

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  • Keep all drains, scuppers, gutters, and downspouts free of debris and vegetation that may restrict proper flow.
  • Prune trees that may hang over the roof to prevent an accumulation of tree leaves and branches that may clog or slow roof drainage.
  • Improve ventilation. An option for improving roof ventilation is to install electric power vents with thermostats.

Workplace Safety Tips for Winter

The following is an excerpt from the article “Workplace Safety Tips for Winter” For more information please visit safetyrisk.com.au

Workplace Safety Tips for Winter

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If you or your employees work in a field and location where winter weather presents some safety concerns, you may wish to take some precautions.  Winter presents safety
hazards in possible frostbite, wind-chapped skin, and hypothermia, and winter weather can often be severe enough to cause amputation or death.  The following are some free tips to offer your employees if they are working in severe winter elements:

  • Dress warm enough to withstand the lowest forecasted temperature or wind chill temperature.  Dress in layers you can remove if you begin to sweat, because sweating will increase your chance of hypothermia.
  • Cover all of your exposed skin in sub-zero weather, including your face, your hands, your neck, and your eyes (wearing goggles can protect the skin around your eyes).
  • Wear long underwear rated for cold weather.  The best winter weather underwear will be made of polypropylene to keep water away from the skin.
  • Wear mittens instead of gloves, if possible, because when your fingers touch one another, they will maintain more warmth.  Do not take your mittens or gloves off for extended periods of time, and never take them off in extreme sub-zero temperatures.  Your fingers and toes are subject to frostbite the quickest because they are farthest from your core and have the smallest surface area.
  • Wear proper socks and boots.  Waterproof boots will keep your feet dry, while multiple layers of socks and spare socks offer you the opportunity to remove or add layers.
  • Take frequent breaks in warm, dry areas to warm up.
  • Drink warm, sweet beverages that do not contain caffeine or alcohol.
  • Eat hot, high-calorie foods to encourage your body to burn the foods and keep you warm.
  • Work during the warmest part of the day, and work in pairs or groups
  • Do not overwork yourself or work to exhaustion, because you may expend all of the energy needed to keep your muscles warm.

Preventing Ice Dams on Businesses

The following is an excerpt from the article “Preventing Ice Dams on Businesses.” For more information please visit disastersafety.org.

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Reducing the risk of ice dams forming will help avoid water damage.

Ice dams are ridges of ice that form at the edge of a roof or around drains and prevent melting snow from draining off your roof. The water that backs up behind this ice dam can leak into the building and cause damage to walls, ceilings, insulation and other areas. Additionally, when the roof doesn’t drain properly, snow, ice and water remains trapped on the roof, adding loads that put your roof at greater risk of collapse.

Safely removing the snow will remove the source of the ice dam.

Stranded in Your Car

This is an excerpt from the article, “Winter Weather: Outdoor Safety”  For more information please visit http://www.bt.cdc,giv

What to Do if You Get Stranded In Your Car

Staying in your vehicle when stranded is often the safest choice if winter storms create poor visibility or if roadways are ice covered. These steps will increase your safety when stranded:

  • Tie a brightly colored cloth to the antenna as a signal to rescuers and raise the hood of the car (if it is not snowing).
  • Move anything you need from the trunk into the passenger area.
  • Wrap your entire body, including your head, in extra clothing, blankets, or newspapers.
  • Stay awake. You will be less vulnerable to cold-related health problems.
  • Run the motor (and heater) for about 10 minutes per hour, opening one window slightly to let in air. Make sure that snow is not blocking the exhaust pipe—this will reduce the risk of carbon monoxide poisoning.
  • As you sit, keep moving your arms and legs to improve your circulation and stay warmer.
  • Do not eat unmelted snow because it will lower your body temperature.
  • Huddle with other people for warmth.

Tips for Shoveling and Snow Blowing

This is an excerpt from the article, “prevent Snow Shoveling and Snow Blowing Injuries”  For more information please visit orthoinfo.aaos.org.

Tips for Snow Shoveling

  • Warm-up your muscles. Shoveling can be a vigorous activity. Before you begin this physical workout, warm-up your muscles for 10 minutes with light exercise.
  • Pace yourself. Snow shoveling and snow blowing are aerobic activities. Take frequent breaks and prevent dehydration by drinking plenty of fluids. If you experience chest pain, shortness of breath, or other signs of a heart attack, stop the activity and seek emergency care.
  • Proper equipment. Use a shovel that is comfortable for your height and strength. Do not use a shovel that is too heavy or too long for you. Space your hands on the tool grip to increase your leverage.
  • Proper lifting. Try to push the snow instead of lifting it. If you must lift, do it properly. Squat with your legs apart, knees bent, and back straight. Lift with your legs. Do not bend at the waist. Scoop small amounts of snow into the shovel and walk to where you want to dump it. Holding a shovelful of snow with your arms outstretched puts too much weight on your spine. Never remove deep snow all at once. Do it in pieces.
  • Safe technique. Do not throw the snow over your shoulder or to the side. This requires a twisting motion that stresses your back.

Tips for Snowblowing

  • Never stick your hands in the snowblower! If snow jams the snowblower, stop the engine and wait more than 5 seconds. Use a solid object to clear wet snow or debris from the chute. Beware of the recoil of the motor and blades after the machine has been turned off.
  • Proper supervision. Do not leave the snow blower unattended when it is running. Shut off the engine if you must walk away from the machine.
  • Safe fueling. Add fuel before starting the snow blower. Never add fuel when the engine is running or hot. Do not operate the machine in an enclosed area.
  • Avoid the engine. Stay away from the engine. It can become very hot and burn unprotected flesh.
  • Watch the snowblower cord. If you are operating an electric snow blower, be aware of where the power cord is at all times.
  • No tampering. Do not remove safety devices, shields, or guards on switches, and keep hands and feet away from moving parts.
  • Watch for motor recoil. Beware of the brief recoil of motor and blades that occurs after the machine has been turned off.
  • Keep children away. Never let children operate snowblowers. Keep children 15 years of age and younger away when snowblowers are in use.
  • Understand your machine. Read the instruction manual prior to using a snowblower. Be familiar with the specific safety hazards and unfamiliar features. Do not attempt to repair or maintain the snowblower without reading the instruction manual.