The Dormer Geometries calculator computes the diagram measurements for a dormer based on the dormer width, depth, pitch of the dormer and pitch of the roof.![](https://www.vcalc.com/attachments/df6e1de8-0d09-11ed-8155-bc764e203090/Dormer-Surface-Area.JPG)
INSTRUCTIONS: Choose units and enter the following:
- (DD) Dormer Depth
- (DW) Dormer Width
- (P2) Pitch of Dormer Gable (choose pitch from list)
- (P1) Pitch of Main Roof (choose pitch from list)
Dormer Geometries (DG): The calculator returns the lengths in inches as follows:
- (h) Height of Dormer
- (x) Edge Length of Dormer
- (y) Ridge Length of Dormer
- (k) Prominence of Dormer
- (j) Valley Length of Dormer
The Math / Science
Dormers can be small or large, but if they conform to the basic shapes below, the math still works.
![](https://www.vcalc.com/attachments/a087180d-0c4f-11ed-8155-bc764e203090/Roof Dormer Geometries.JPG)
- Surface Area of Dormers: This computes the roofing surface area for dormers based on the dimensions and number of dormers.
- Metal for Dormers: This computes the metal roof materials (panels, ridge cap and trim) for one or more roof dormers based on the dimensions
- Screws for Metal Dormers
: This computes the number of metal panels screws needed for one or more roof metal paneled dormers based on the dimensions.
- 4x8s for Dormers: This computes the number of 4x8 sheathing needed for one or more roof dormers based on the dimensions.
- Shingles for Dormers: This computes the number of shingle bundles needed for one or more roof dormers based on the dimensions. It also includes ridge shingles, valley lengths for flashing, and roofing nails.
- Underlayment for Dormers: This computes the amount of underlayment needed and estimates the cost of underlayment materials.
- Roofing Nails for Dormers: This computes the number and weight of roofing nails needed for one or more roof dormers based on the dimensions.
- Purlins for Dormers: This computes the total number and length of purlins (roof support boards) for needed for one or more roof dormers based on the dimensions.
- Dormer Geometries: This computes the diagram measurements for a dormer based on the dimension.
Roof Types
![](https://www.vcalc.com/attachments/fc48ca2c-f32b-11ed-8f09-bc764e203090/types-of-roof.PNG)
Roofing Calculators