Do not force a simple approximation
A slope multiplier can convert a known compatible plan area at one pitch. It cannot discover the plan areas of intersecting planes, hip triangles or dormer returns from a building rectangle alone.
If reliable drawings or a professional takeoff give separate plan areas and pitches, enter each supported planar section with a clear label. Otherwise declare the form unsupported.
What the workbench records
The workbench adds measured section subtotals; it does not create a roof model. Preserve the source for each area and avoid double counting overlaps or omissions.
These calculations describe geometry only. They do not size rafters or trusses, assess loads, approve a design, interpret building codes, specify cuts or fasteners, or guarantee material quantities.
Roof work can cause serious injury. Do not climb onto a roof merely to collect inputs. Prefer drawings, ground-level measurements, accessible interior information or dimensions supplied by a competent professional.
Detailed field guide
A hip roof introduces triangular and trapezoidal planes; a valley joins inward slopes; a dormer creates additional faces and overlap boundaries. None can be recovered from one building rectangle and one pitch alone.
The calculator can still process a plane whose horizontal plan area and pitch are independently known. Name it clearly and retain the drawing or takeoff that established its boundary.
Avoid double counting where plan projections overlap and avoid omissions at returns. The workbench adds supplied sections but has no spatial model that could detect either error.
If reliable plane boundaries, pitches and endpoints are unavailable, obtain a professional roof takeoff. Unsupported geometry should remain explicitly unsupported.
Checks before using the result
- Preserve the original measurement, unit, endpoints and drawing revision.
- Keep different pitches and unsupported intersections separate.
- Compare one representative result with an independent calculation.
- Do not access a roof merely to obtain calculator inputs.
Why one factor is insufficient
Hips, valleys and dormers change the number and outline of planes. Even when every plane shares a pitch, their horizontal projections must be known before a factor can be used. An outside building rectangle contains no information about internal junction lines or dormer faces.
Create a plane schedule
Assign each known plane a unique name, pitch, plan-projection boundary and source reference. Mark shared edges so adjacent sections meet without overlap. Enter only the resulting non-overlapping projections in the workbench and reconcile their combined plan area with the supported drawing.
Treat intersections as evidence problems
A valley line or dormer cheek cannot be guessed from a photograph alone when dimensions, pitch or offsets are unknown. Leaving the section unsupported is more honest than forcing it into a rectangle. Obtain a measured takeoff or suitable design information when the boundary matters.
Keep area separate from detailing
Plane area does not quantify flashing, valley lining, ridge or hip caps, cuts and junction waste. Those quantities depend on product and construction details. Export the geometric schedule as a checked base record and apply documented takeoff rules separately.
Recognise when the overall footprint is insufficient
Hips, valleys and dormers change the number, shape and boundary of roof planes. Even if every plane uses the same pitch, the outside building rectangle does not reveal the internal junction lines or dormer faces. A single multiplier applied to that rectangle may omit projections, count overlap or ignore vertical and low-slope surfaces. The correct starting point is a plane schedule based on reliable drawings or measurements, not an assumed percentage added to a simple roof.
Name each plane, state its pitch, identify its horizontal projection and mark shared edges. The projections should meet without gaps or overlap. Reconcile their combined plan area with an independent drawing quantity where possible. Only then apply the appropriate factor to each plane and add the sloping subtotals. This method makes uncertainty visible and allows one plane to be corrected without changing unrelated parts of the job.
Treat junctions as evidence, not calculator, problems
A valley line depends on the intersecting plane geometry and relative positions. A dormer adds its own roof and cheek boundaries. A hip changes the plane outline even when the main pitch is known. RoofFigured does not infer those dimensions from a photograph, footprint or roof style label. If an offset, pitch or edge is unknown, the associated section is unsupported until suitable design information or a competent measured takeoff supplies it.
Do not disguise missing evidence by creating convenient rectangles whose areas happen to sum to the footprint. A numerical total can be precise and still be wrong because the plane boundaries were invented. Record exclusions explicitly—for example, “north dormer not included; no verified projection available.” That note is more useful to a reviewer than an unexplained allowance and prevents the subtotal from being mistaken for a complete roof quantity.
Keep detailing and waste outside the plane schedule
Ideal plane area does not quantify valley lining, hip or ridge caps, flashing, dormer cladding, cut patterns or junction waste. Those requirements depend on product dimensions and construction details. Export the checked geometric schedule first. Then apply documented coverage and waste assumptions separately, preserving the source for each. This separation prevents a change in product or layout from rewriting the measured geometry.
Complex geometry is also not a reason to take unsafe measurements. Prefer drawings, ground-based survey information and competent professionals. The workbench is designed to aggregate known supported sections, not to replace surveying, structural design or trade takeoff. Stop when a plane cannot be defined confidently; do not climb onto the roof or use the software’s ability to add rows as justification for guessing.
Example of a defensible partial record
A drawing may provide reliable projections for four main hip planes but omit the dimensions of a later dormer. Enter the four known planes with their names, pitches and plan areas, then state plainly that the dormer roof and cheeks are excluded. Do not estimate the dormer from a photograph or absorb it into a generic waste allowance. The exported subtotal is then a defensible partial geometric record rather than an unqualified claim about the entire roof.
If revised drawings later establish the dormer projection, add new labelled sections and rerun the plan-area reconciliation. Preserve the earlier export and drawing revision so the change is auditable. Shared valley or hip edges do not themselves add plane area, but associated coverings and flashings may create separate quantities under a product-specific method. Keeping that work outside the plane schedule avoids mixing ideal geometry with construction detailing and allows each source to be reviewed on its own terms.
Final verification before use
The completion test for a complex roof is a labelled plane drawing, not a plausible grand total. Every entered row should map to one non-overlapping projection and one supported pitch. Every unmeasured dormer, cheek or junction should be named as excluded. Retain the plan reconciliation and source revision so later additions can be incorporated without losing the distinction between verified and unresolved geometry.
When a professional takeoff supplies finished plane areas directly, keep those source values and do not reverse-engineer new rectangles merely to fit the workbench. Direct-area rows can preserve the supplied projections when their meaning and pitch are documented. Note whether the source area is horizontal or already sloping; applying a factor to an already sloping area would inflate it. Ambiguity must be resolved before entry.
Review the final schedule against the plan visually and numerically. Each plane should appear once, shared edges should not create duplicate area, and exclusions should remain prominent beside the total. A later product estimate can then reference the verified plane record without claiming that RoofFigured calculated the junction detailing or associated accessories.