Commentary on Snow Loads

1,27

MB

32

stron

6374

ID

UNITED STATES ARMY CORPS OF ENGINEERS

1998

rok

Table of Contents

Paragraph 1. Purpose and Scope 1

2. Applicability 1

3. References 1

4. Building Configuration. 1

5. Unbalanced Loads. 2

6. Metal Buildings 2

7. Internally Drained Membrane Roofing Systems. 2

8. Building Orientation 2

9. Sliding Snow 2

10. Icicles and Ice Dams. 3

11. Snow Guards. 3

1 The peak snow load of this drift was 130 psf. The ground snow load then was 20 psf, and the

snow load on the upper roof was 15p sf . 4

2 Snow drifts and their consequences 5

3 Unbalanced snow loads on a saw-tooth roof 6

4 Orienting buildings with respect to the known direction of winter storm winds can reduce actual

drifting even though design loads do not change. 7

5 Snow sliding off a metal roof 8

6 Army van damaged by snow and ice that fell from a roof. 9

7 The creep and glide of snow down a slippery roof can create dangerous cornices 10

8 Plumbing stack displaced by snow creeping down a slippery metal roof11

9 Tear in metal roofing caused by the plumbing stack displacement shown in figure 812

10 Parapet capstone displaced by snow moving down the adjacent roof valley 13

11 Metal roof fascia torn by moving snow14

12 Metal standing seams broken and displaced by snow moving down a valley .15

13 Plan view of a gable-roofed building showing some sliding snow issues.16

14 Snow creep can create cornices that cause several problems17

15 Electrical service entrance cables should not be located below cold eaves.18

16 Scuppers are often not appropriate as primary drains for low slope roofs in cold regions19

17 Massive icings all along a metal roof over a warm attic.20

18 When a cold eave is not present, ice may form on building walls21

19 Removal of snow and ice is dangerous and often damages the roof.22

20 Electric heaters can create tunnels which prevent ponds from forming on roofs behind ice

dams.23

21 Electric heaters zigzagged along the eaves of a residence to prevent ponding of water behind ice

dams.24

22 Fence type snow guards installed on a metal roof .25

23 Plastic snow guards adhered to a metal roof .26

24 Two rows of aluminum angle snow guards spaced well apart up a metal roof.27