Determining Snow Loads **

1. Measure with a ruler the depth of the snow down to the ground. (D)

2. Take a five gallon bucket.

3. Weigh the empty bucket (B)

4. Fill the bucket with snow and level off. Be sure to dig straight down to the ground in the same area so you have a representative sample of the snow.

5. Weigh the bucket with the snow in it. (WB)

6. Subtract the weight of the bucket. (WB - B) = (W)

7. The resulting weight is the weight of 5 gallons of snow. (W)

8. For a house with a sloped roof, divide that number (W) by 10. W/10 = lbs per inch (WPI) per square foot.

9. If you have a flat roof, disregard step 8. Instead, divide the number (W) by 9. W/9 = lbs per inch (WPI) per square foot.

10. Multiply by the total amount of inches from the ground to the top of the snow (D) by (WPI) to find the weight of the snow (S). D x WPI = S. S is the weight of an equivalant amount of snow in lbs per square foot on your roof.

11. If you find ice, ice weighs the same as water, roughly 6 lbs per inch. For every inch (or portion thereof) you have to multiply the number of inches of ice by 6 (I). Inches of Ice x 6 = I. I is the weight of an equivalent amount of ice on your roof per square foot.

12. Add the Snow Weight (S) to the Ice Weight per Inch (I) to find the total weight on the roof. S + I = P. P is the total weight in lbs per square foot equivalent of ice and snow on your roof.

13. Look for your town on the table to know if you are under the amount. If house is older than 30 years, use 30 lbs per square foot, if younger, use page 28 with the table. Find the link here: http://www.ct.gov/dcs/lib/dcs/office_of_state_building_inspector_files/2009_amendment_5-6-09.pdf

14. If your total weight (P) exceeds the design load for your town, it is structurally unsatisfactory and you should take steps to immediately remove the snow. Your structure should be inspected by a structural engineer, such as Scalzo Engineering, or a building inspector.

15. If you are anticipating more snow, ice or rain, and have exceeded the limit, take action.

Example:

(D) = 12”

(B) = 1 lb

25 lbs (WB) – 1 lb (B) = 24 lbs (W)

(W) = 24 lbs

24(W)/10 = 2.4 lbs per inch (WPI)

12 (D) x 2.4 (WPI) = 28.8 (S) lbs per square foot (psf)

1/2 Inch of ice x 6 = 3 (I) psf

28.8 (S) + 3 (I) = 31.8 (P) psf

For the town of Andover, the limit is 30 for psf or P, according to the chart on page 28 at http://www.ct.gov/dcs/lib/dcs/office_of_state_building_inspector_files/2009_amendment_5-6-09.pdf

For our example, if your home is in Andover, it would exceed the limit and it is structurally unsatisfactory and you should take steps to immediately remove the snow. Your structure should be inspected by a Structural Engineer, such as Scalzo Engineering, or your town’s Building Inspector.

**This is a procedure for

1. Measure with a ruler the depth of the snow down to the ground. (D)

2. Take a five gallon bucket.

3. Weigh the empty bucket (B)

4. Fill the bucket with snow and level off. Be sure to dig straight down to the ground in the same area so you have a representative sample of the snow.

5. Weigh the bucket with the snow in it. (WB)

6. Subtract the weight of the bucket. (WB - B) = (W)

7. The resulting weight is the weight of 5 gallons of snow. (W)

8. For a house with a sloped roof, divide that number (W) by 10. W/10 = lbs per inch (WPI) per square foot.

9. If you have a flat roof, disregard step 8. Instead, divide the number (W) by 9. W/9 = lbs per inch (WPI) per square foot.

10. Multiply by the total amount of inches from the ground to the top of the snow (D) by (WPI) to find the weight of the snow (S). D x WPI = S. S is the weight of an equivalant amount of snow in lbs per square foot on your roof.

11. If you find ice, ice weighs the same as water, roughly 6 lbs per inch. For every inch (or portion thereof) you have to multiply the number of inches of ice by 6 (I). Inches of Ice x 6 = I. I is the weight of an equivalent amount of ice on your roof per square foot.

12. Add the Snow Weight (S) to the Ice Weight per Inch (I) to find the total weight on the roof. S + I = P. P is the total weight in lbs per square foot equivalent of ice and snow on your roof.

13. Look for your town on the table to know if you are under the amount. If house is older than 30 years, use 30 lbs per square foot, if younger, use page 28 with the table. Find the link here: http://www.ct.gov/dcs/lib/dcs/office_of_state_building_inspector_files/2009_amendment_5-6-09.pdf

14. If your total weight (P) exceeds the design load for your town, it is structurally unsatisfactory and you should take steps to immediately remove the snow. Your structure should be inspected by a structural engineer, such as Scalzo Engineering, or a building inspector.

15. If you are anticipating more snow, ice or rain, and have exceeded the limit, take action.

Example:

(D) = 12”

(B) = 1 lb

25 lbs (WB) – 1 lb (B) = 24 lbs (W)

(W) = 24 lbs

24(W)/10 = 2.4 lbs per inch (WPI)

12 (D) x 2.4 (WPI) = 28.8 (S) lbs per square foot (psf)

1/2 Inch of ice x 6 = 3 (I) psf

28.8 (S) + 3 (I) = 31.8 (P) psf

For the town of Andover, the limit is 30 for psf or P, according to the chart on page 28 at http://www.ct.gov/dcs/lib/dcs/office_of_state_building_inspector_files/2009_amendment_5-6-09.pdf

For our example, if your home is in Andover, it would exceed the limit and it is structurally unsatisfactory and you should take steps to immediately remove the snow. Your structure should be inspected by a Structural Engineer, such as Scalzo Engineering, or your town’s Building Inspector.

**This is a procedure for

**approximately**determining the weight of snow and ice per square foot on your roof and should not take the place of professional structural analysis. For further information, contact ScalzoEngineering.com, scalzoengineering@sbcglobal.net or call (860) 669-4900.