What is a safe snow load for my roof?

Safe snow loads depend on your roof design and construction. Typically, residential roofs can handle 20-70 pounds per square foot (psf). Flat roofs have lower capacity (20-30 psf) while steep roofs can handle more. Always consult local building codes and consider professional assessment for heavy snow conditions.

How does roof pitch affect snow load?

Steeper roof pitches reduce snow accumulation and load. Snow naturally slides off roofs with pitches above 30 degrees. Flat roofs retain all snow, while gable and hip roofs may have uneven snow distribution. The slope factor calculation accounts for this in the load determination.

When should I remove snow from my roof?

Remove snow when the load exceeds 70% of your roof's design capacity, typically around 30-50 psf for most residential roofs. Signs of concern include sagging ceilings, cracking sounds, or visible roof deflection. Always prioritize safety and consider professional snow removal services.

What factors affect snow density and weight?

Snow density is affected by temperature (colder snow is lighter), moisture content (wet snow is heavier), age (older snow compacts and becomes denser), and wind (wind-packed snow is denser). Fresh dry snow weighs about 10 pcf, while wet snow can weigh 20-30 pcf, and ice weighs 57 pcf.

How can I prevent ice dams and roof damage?

Prevent ice dams by ensuring proper attic insulation and ventilation, keeping gutters clear, using ice and water shield under shingles, and removing snow from roof edges. Maintain consistent roof temperature to prevent snow melting and refreezing at eaves.

Snow Load Calculator

Roof Parameters

Location

Select region

Roof Type

Select roof style

Roof Pitch

Roof slope

Snow Depth

Snow accumulation

Snow Type

Select snow condition

Calculation Results

Snow Load Calculator: Your Guide to Roof Safety

Need to calculate snow load on your roof? Our Snow Load Calculator helps you determine the weight of snow accumulation and assess potential structural risks.

Understanding Snow Load Calculations

Snow load calculations are important for several reasons:

Structural Safety: Prevent roof collapse
Building Codes: Meet local requirements
Insurance: Maintain coverage
Maintenance: Plan snow removal
Design: Optimize roof structure

How to Use the Snow Load Calculator

Select Location: Choose your region
Select Roof Type: Choose roof style
Enter Roof Pitch: Input slope angle
Enter Snow Depth: Input accumulation
Select Snow Type: Choose condition
Click Calculate: Get load estimate

Snow Load Calculation Formula

Basic Load Calculation:
L = D × ρ × C

Slope Factor:
C = 1 - (P/70)

Where:
L = Load (psf)
D = Depth (inches)
ρ = Density (pcf)
C = Slope factor
P = Pitch (degrees)

Common Snow Load Specifications

Northeast Region:
- Design Load: 40-70 psf
- Snow Type: Mixed
- Density: 15-30 pcf
Northwest Region:
- Design Load: 30-50 psf
- Snow Type: Wet
- Density: 20-25 pcf
Midwest Region:
- Design Load: 20-40 psf
- Snow Type: Dry
- Density: 10-15 pcf

Real-World Examples

Example 1: Northeast Gable Roof

Location: Northeast
Roof Type: Gable
Pitch: 30 degrees
Snow Depth: 24 inches
Snow Type: Mixed
Results:
- Snow Load: 45.7 psf
- Total Weight: 18,280 lbs
- Safety Factor: 1.5
- Risk Level: Moderate

Example 2: Midwest Flat Roof

Location: Midwest
Roof Type: Flat
Pitch: 0 degrees
Snow Depth: 12 inches
Snow Type: Dry
Results:
- Snow Load: 15.0 psf
- Total Weight: 6,000 lbs
- Safety Factor: 2.0
- Risk Level: Low

Frequently Asked Questions

What is a safe snow load?

Depends on roof design, typically 20-70 psf for residential.

How does roof pitch affect load?

Steeper pitches reduce snow accumulation and load.

When should I remove snow?

When load exceeds 70% of design capacity.

What affects snow density?

Temperature, moisture content, and age of snow.

How do I prevent ice dams?

Proper insulation, ventilation, and snow removal.