The Metal for a Dormer calculator computes the metal roof materials for one or more roof dormers based on the dimensions.
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)
- (n) Number of Dormers
- (PW) Panel Width (default 36"). This is the coverage width and not necessarily the measured width of the metal panels.
- (TO) Tolerance (default 3"). This is added to trim and panel lengths as a safety margin.
Metal for a Roof Dormer (m): The calculator returns:
- (TA) Area: Total surface area of dormer(s).
- (r) Ridge Cap: Length of the Ridge Cap (red)
- (j) Valley Trim Length: Length of each individual hip ridge
- (sG) Snow Guard: Total length of snow guard to for under the ridge cap.
- Metal Panels: Number and max length of Metal Panels (36" wide coverage)
- (PL) Length of Panels
- (nP+) Number of Panels with no-reuse. This is conservatively high.
- (nP-) Number of Panels with reuse of cuts. This accounts for one panel used in multiple segments in the hips (see ECONOMY below)
- (α) Panel Angle: The angle of the hip cuts
- (mS) Metal Screws: number of screws needed to attach panels to roof.
- (aT) Angle Trim: Total length of Angle Trim (yellow)
However, these can be automatically converted to compatible units via the pull-down menu.
ECONOMY: This calculator provides two numbers of panels. The first (nP+) is a high number with no reduction in the number of panels based on reusing panel leftovers for additional sections (see graphic). When smaller sections are cut out of a panel of maximum length, it is possible in many cases to use the residual (leftover) for another section. This maximum number assumes that a full panel will be used for each section and therefore provides the maximum number of metal panels needed. The second (nP-) number of panels is lower, because it assumes that cuts making the hip ends will produce leftover pieces that can also be used (see diagram).
The Math / Science
Safety Tolerances
An addition of the TO parameter (default of 3") s added to the following dimensions.
- (r) Ridge Cap
- (sG) Snow Guard
- (j) Valley Trim
- (PL) Panel Length
- (aT) Angle Trim
It's better to have too much and have to cut it, than not enough.
Roof Calculators
- Gabled Roof
- Hip Roof
- Shed Roof
- Dormers
Building Calculators
- Total Building Materials Calculator
- Pitch of a Roof - Computes angle of incline in the roof in both degrees and rise over 12" run (e.g. 26.6o : 6/12) based on the length of the rise and run.
- Number of Trusses Needed for a Roof - number of trusses needed based on the roof width and the truss spacing.
- 4x8s needed for a roof - Calculates the number of 4x8 sheets needed to cover a roof.
- Roofing nails needed for a roof - Calculates the number of roofing nails needed for a roof in normal and high wind conditions.
- Number and Length of Metal Roof Panels - Computes the length and number of metal panels and trim pieces for a metal roof.
- Screws for a Metal Roof - Computes the number of screws needed for a metal roof.
- Number and Length of Purlins for a Roof - Computes the number of purlins for a roof based on dimensions and spacing.
- Number and Length of Rafters - Computes the number and length of rafter boards based on roof dimensions and spacing.
- Number and Length of Rafter and Collar ties - Computes the number and length of rafter ties and collar ties based on roof dimensions and spacing.
- Number and Length of wall top and bottom wall plates
- Number of Studs for a Room
- Number of Studs in a Wall
- Room Interior Area (wall and ceiling)
- Cubic Feet in a Room (volume)
- Number of 4x8 or 4x12 Sheets for a Room
- Number and Length of Floor Joists
- Number of Joist Hangers
- Compute the Cost of Floor Joists
- Compute iJoists for larger floors
- Compute the Number of 4x8 Sheets to cover the Deck or Floor
- Compute the number of Decking Boards to cover the deck or floor
Roofing Geometry Calculators