The Underlayment for Gable Roof calculator estimates the cost of underlayment to cover a basic gable roof based on
the area of a roof computed from the dimensions (length, span, pitch and overhang) and the unit price underlayment material.
INSTRUCTIONS: Choose units and enter the following;
- (L) Ridge Length of Roof
- (S) Span of Roof
- (P) Pitch of Roof
- (oH) Overhang of Roof
- (uP) Unit Price per Square Foot of Underlayment Material
Cost of Roof Underlayment (TC): The calculator returns the total square feet in underlayment and the estimated cost in U.S. dollars. However, these can be automatically converted compatible units via the pull-down menu.
Note, the default Unit Price per Square Foot is equal to the cost of Polypropylene below. Enter any other value you wish to override the default.
The Math / Science
The surface area of a gable roof is easy to compute based on the span, ridge length, overhang and pitch of the roof. This calculator uses those specifications to compute the surface area of the roof. Once the surface area is known, the unit pricing (cost per square foot of underlayment) can be easily applied.
Underlayment comes in different types of materials and in different sizes of products measured in square feet. To compute the Unit Price per Square Feet CLICK HERE. A pop-up calculator will let you enter the product size (e.g., 265 square feet) and the total cost and will return the dollars per square feet.
Underlayment Pricing Data
The underlayment pricing data contains the following information in each record.
- Underlayment Pricing Survey Date: 1/2/23
- Underlayment Pricing Survey Store: Lowes
- Price of Felt Underlayment: $0.12 USD/ft²
- Price of Polypropylene Underlayment: $0.36 USD/ft²
- Paper (red rosin) Underlayment: $0.03 USD/ft²
- Rubber Underlayment: $0.95 USD/ft²
- Rubberized Asphalt Underlayment: $0.61 USD/ft²
- Synthetic Underlayment: $0.08 USD/ft²
All pricing is in U.S. dollars per square feet of underlayment.
NOTE: Local pricing should ALWAYS, ALWAYS, ALWAYS be used! These price points are for estimation convenience only, and there is no guarantee on the prices of the product nor of their availability at the listed price.
Underlayment is installed beneath the outer roofing material (shingles or metal panels) and directly on top of the roof deck. Its primary purpose is to provide an extra layer of protection against water infiltration and to enhance the overall weather resistance of the roof.
Underlayment Calculators
- Underlayment for a Gable Roof: Estimates the cost of underlayment to cover a basic gable roof based on the area of a roof computed from the dimensions (length, span, pitch and overhang) and the unit price underlayment material.
- Underlayment for a Hip Roof: Computes the surface area of a hip roof based on the dimensions and uses the surface area to compute the cost of underlayment based on the unit price (price per square feet) of underlayment material.
- Underlayment for a Gambrel Roof: Computes the total surface area of a gambrel roof for underlayment based on the dimensions below and the estimated cost based on the area and unit price of underlayment material.
- Underlayment for a Shed Roof: Computes the surface area of a shed roof and the cost estimate for underlayment based on the roof dimensions and a unit price of underlayment.
- Pyramid Roof Underlayment: Computes the surface area of a pyramid hip roof based on the dimensions, and uses the surface area to compute the cost of underlayment based on the unit price (price per square feet) of underlayment material.
- Underlayment of Dormers: This computes the amount of underlayment needed for one or more dormers and estimates the cost of underlayment materials.
Gable Roof Calculators
- Gable Roof Area: This computes the surface area of a gable roof based on dimensions and pitch.
- Trusses Needed for Roof: This computes the number trusses need for a roof including gabled roof.
- 4x8 Sheathing for Gable Roof: This computes the total surface area of a roof, the number of 4x8s and framing nails needed for a gabled roof based on the length, span, pitch and overhang.
- Gable Roof Sheathing Cost: This computes the number of 4x8 sheets (32 ft² each) needed to cover a gabled roof based on the ridge length, roof span, overhang and the pitch and applies the unit cost of a 4x8.
- Nails for Gable Roof Sheathing: This computes the approximate number of nails needed to nail 4x8 sheets to trusses or rafters on a roof based on the dimensions of the roof, spacing of nails on the edges and field of the 4x8, and whether blocking or clips are use.
- Purlins for Gable Roof: This computes the total number and length of purlins for a simple gable roof based on the ridge length of the roof, the roof pitch and the span of the roof.
- Metal for Gable Roof: This estimates the metal panels and trim needed for a metal roof for a simple gabled roof based on the roof dimensions.
- Metal Screws for Gable Roof: This computes the number of special screws needed for a metal roof.
- Shingles for Gable Roof: This computes the number of shingles (bundles), underlayment, ridge shingles, starter strip, and roofing nails for a gable roof.
- Gable Roof Shingle Cost: This estimates to shingle a basic gable roof based on dimensions (length, span, pitch and overhang) and the unit price of a bundle of shingles.
- Underlayment for Gable Roof: This estimates the cost of underlayment to cover a basic gable roof based on the area of a roof computed from the dimensions (length, span, pitch and overhang) and the unit price underlayment material.
- Roofing Nails for Gable Roof: This estimates the number of roofing nails needed for a common gabled roof based on roof dimensions and wind conditions.
- Rafters for Gable Roof: This computes the total number of rafter boards (roof joists) for a gabled roof based on the ridge length, pitch and span. It also returns the length of the ridge board, and the length and number of rafter ties and collar ties.
- Rafter Length: This computes the length of the rafters based on the span, pitch and overhang.
- Gable Roof Geometries: This computes the length of rafters, pitch and cut angles, soffit and facia base widths of a gable roof.
- Weight of Snow on Roof: This computes the weight of snow on a gable roof based on roof dimensions, depth and type of snow.