Estimating Roof Loss
Roof Inspections
- 1. Identify the roof design/components
- 2. Identify the roof material
3. Identify damage - 4. Identify the source of ensuing damage.
Ccomponents of a typical Roof system
Types of Roof Design
- 1. Flat
2. Gable
3. Hip and Ridge
4. Mansard
5. Gambrel
Flat Roof - Common in commercial construction
Eave Length X Eave Width = Square footageThe formula for converting to Squares:
Total Square footage ÷ 100 = Number of Squares
30 x 90 = 2,700 square feet or 27 squares
Gable Roof - Common in residential construction
The formula for a Gable Roof is:
Roofs are measured in Squares / 1 square = 100 square feetRafter Length X Eave Length = Square footage
The formula for converting to Squares:
Total Square footage ÷ 100 = Number of Squares
14(2) x 60 = 1,680 square feet or 16.8 squares
Hip and Ridge Roof - Wind resistant
The formula for a Hip and Ridge Roof is:
Rafter Length X Eave Length = Square footageThe formula for converting to Squares:
Total Square footage ÷ 100 = Number of Squares
14(2) x 60 = 1,680 square feet or 16.8 squares
Intersecting Roof - Can combine Hip and Gable
Roof Calculations:
18(2) x 80=288012(2) x 10=240
Total 3120
3120 Total Square footage ÷ 100 = 31.20 squares
Gambrel Roof - Barn roof
The formula for a Gambrel Roof is:
Rafter Length X Eave Length = Square Footage(15+10+10+15) x 75 = 3,750 Square footage or 37.50 squares
Mansard Roof
The formula for a Mansard Roof is:
Trapezoid - ((b1+b2)/2) x Height = Square Footage
Rectangle - Length X Width = Square Footage
(10+30)÷2=20 20x14=280 280x2=560
(20+60)÷2=40 40x14=560 560x2=1120
Area of Trapezoids: 560+1120=1680
Area of Rectangle: 20x20= 200
Total Area of Roof: 1880
Common Roofing Materials
Composition Asphalt Shingles
• Organic - saturated felt with asphalt and ceramic granules.
• Glass Fiber - Asphalt with Fiberglass and ceramic granules.
The ceramic granules are to protect the shingle from the sun’s UV rays and for aesthetics.
Common types of Composition Shingles are:
• 3 Tab Shingles
• Laminate/Dimensional/Architectural
• Individual Shingles
• Roll
3 Tab and Dimensional Shingles
3 Tab Shingles
3 Bundles per square
20-25 year life span
Laminate and/or Dimensional Shingles
4 Bundles per square
25-35 year life expectancy
Architectural and Individual Shingles
Common Composition Shingles:
Architectural Shingles
4 Bundles per square
30-35 year life span
Individual Shingles
4 Bundles per square
25-35 year life expectancy
Wood and Metal Roofing
Other Types of Shingle Material:
- Wood - Shake and Shingle
- Metal - Aluminum and Steel
- Rigid - Clay and Cement
- Synthetic - Rubber
Wood Shakes - 5 bundles per square  |
Wood Shingles - 4 bundles per square  |
Metal Shingles - price by square foot  |
Metal Panels - price by square foot  |
Clay and Slate Tiles
Clay Tiles - 5 bundles per square  |
Slate Tiles - 5 bundles per square  |
Additional Roofing Material
- • Ice and Water Shield
• Drip Edge
- • Valley Flashing
- • Gas Appliance Exhaust Vents
- • Attic Ventilation
Common Commerical Roof Systems
Built up Roof (BUR)  |
Built up Roof with gravel  |
Single Ply Membranes – EPDM (Ethylene Propylene Diene Monomer)  |
Identify Roof Damage - typically neither hail or wind causes a leak.
Wind Damage  |
Hail Damage  |
Commercial Roof Damage
Spray Foam Roof – Hail Damage  |
Steel Roof – Hail Damage  |
Built up Roof – Hail Damage |
Identify the Source of the Leak
-
Improper Installation
Deterioration
Repair versus Replacement
Evaluating Loss from Hail Damage
Roof - 1 layer 3 tab shingles - 5-10 years old - Reparability Factors
0-5 years -- reparability factor of .5
5-10 years -- reparability factor of 1.0
10-15 years -- reparability factor of 1.5
15+ years -- reparability factor of 2.0
Test Squares = Average of 8.5 hits per square x RF of 1.0
8.5 x 1.0 = 8.5
therefore to repair each square
8.5 (average hits per square) + 8.5 = 17 shingles per square
Roof Calculations: Total
30 x 60 = 1800 square feet
10% waste = 180 square feet
Total # squares = 1980 which rounds to 20 squares as 3 tab is sold in bundles of 3 per square
Roof Repair: Repair
18 squares x 17 shingles per square = 306 shingles to repair this roof.
306 x $11.71 per shingle = $3,583.26 cost to repair roof.
Roof Replacement
20 squares x $190.00 = $3,800 [Does not include drip edge; ice water shield, vents etc.]
Things to consider before writing the estimate
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Height, Steepness and Accessibility
Material Guage
Steepness - Any roof 6/12 or greater is considered steep
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Accessibility
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Writing the Estimate - Terms
Square – 1 square is a 100 square feet
Linear/Lineal Feet (LF) – length of straight line
Waste – the amount of material lost during installation. [5% Felt/Rolled Roofing; 10% Gable Roof; 15% Hip and Ridge; 20% cut-up roof.
Roof Pitch – rise in inches over a 1 foot run
Unit Cost – price that includes material, labor, overhead, profit and soft costs.
Test
| Cause of Loss: Hail Damage to Roof | |||
| 2 box vents; 1 exhaust vent | Type of Shingles: 3 Tab | 15 years | |
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| Description | Quantity | Unit Price | Replacement Cost |
| Remove 3 tab shingles | 18 squares | ||
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Replace 3 tab shingles |
20 squares | ||
| Replace Felt | 19 squares | ||
| Replace Ridge | 60 Lineal Feet | ||
| Remove and replace ice and water shield | 360 square feet | ||
| Remove and replace box vent | 2 each | ||
| Remove and replace exhaust vent | 1 each | ||
Printable PDF - Estimating Roof Loss