Recommended Procedures for Roof Snow Loads

Recommended Procedures for Roof Snow Loads

Fall 2022/Winter 2023

IMPORTANT NOTICE – To Our Valued Butler Roofing System Owners:


The winter season is here and Dutton & Garfield, Inc. wants to remind you of the recommended procedures to safeguard your Butler roof system.


Heavy and/or repeated snowstorms can create packed snow and ice such that only a few feet of depth may weigh 50 psf or more, imposing unusual and excessive loads on any building structure. Blowing and drifting snow can easily double these loads and rain on snow can significantly increase these loads. An excessive accumulation of snow can cause a building to be loaded beyond capacity creating a risk of building damage and even collapse.


Relatively flat roofs are particularly vulnerable. Most snow-related losses occur at stepped elevations where blowing snow is carried from the roof of a higher building onto the roof of a lower building. Such drifting normally occurs where the buildings are attached. However, drift loads can also form on closely adjacent buildings, over ridges, at valley conditions, behind parapets, next to rooftop units, and on below eave canopies or overhangs. Post construction changes to the building site, added higher buildings, or significant tree growth, can also cause drifting where none was anticipated.

Modifications to the structure, loads applied after the original design (such as piping, roof units, hanging heaters, etc.) and prior damage to the structure are other areas of particular concern because they may significantly reduce the capacity of the building to withstand snow loads.


As a building owner, you should activate a snow watch program to monitor snow depths and excessive accumulations of snow from your roof. Drains and gutters should be clear of ice and snow to facilitate melting run-off. This will prevent ice dams from forming causing water to build up, leading to interior damage. Heat tapes in gutter and downspouts may assist in preventing ice build-up, except during extremely low temperatures.

Warning signs indicating excessive snow accumulation include the deflection of purlins, the popping of ceiling tiles in dropped ceilings, and unusual noises. If any of these situations occur, you should immediately contact Dutton & Garfield, Inc. at (603) 329-5300 or your building manufacturing company

We offer the following tips for successful snow and ice removal:

  1. Always provide proper safety precautions when working on the roof, especially along the edge of the roof. Never send one person on a roof to remove snow alone. Place ladders at the gable end of the building so sliding snow will not dislodge them.
  2. Remove drifted areas first, down to the level of the snow on the remaining roof. Next, remove the snow from the middle 1/3 of each bay (from eave to eave), beginning with the most snow-packed bay. Complete snow removal on the remainder of the building. On gabled buildings, remove snow on both sides of the ridge at the same time.
  3. Remove snow in a pattern that does not cause an unbalanced loading condition. Avoid large differences in snow depth between adjacent areas of the roof. Remove snow gradually in layers from all over the roof.
  4. Remove the snow from the eave toward the ridge but be cautious of snow or ice breaking away and sliding down the roof. Prior to removing snow from the roof, remove all hanging icicles from eaves and gutters. These can be quite heavy and cause snow and ice to hang up.
  5. Do not pile shoveled snow on other areas of the roof or on other roofs. Keep dumping area clear of all persons and property.
  6. Always use plastic shovels. Do NOT use picks, axes, or other sharp tools.
  7. Do not attempt to remove snow by washing it off with a hose. Snow acts like a sponge and will rapidly absorb water, increasing the loads on the roof and potentially causing failure.
  8. Be careful to avoid hitting panel straps, fasteners, snow guards, etc. Care must be taken in removing snow and ice around ventilator bases, pipe flashings, rooftop unit supports, conduits, etc., since such items are easily damaged.
  9. Be aware of skylight systems locations. These panels are not intended to support roof foot traffic loads.

We thank you in advance for taking the time to review and implement these important measures. Should you have any questions or concerns, please feel free to contact Dutton & Garfield, Inc. directly at (603) 329-5300.