Revit Tip: Control Roof Drainage with Revit Slope Arrows

Roof slope arrows are one of the most effective tools for controlling drainage direction and elevation changes in a footprint roof. Unlike selecting individual sketch lines and assigning slopes, a slope arrow gives you direct control over the roof’s rise, run, and drainage intent—especially useful for low-slope roofs, tapered forms, and roofs that must drain to a specific edge or point.

In Revit, use a slope arrow when the roof needs a clear directional fall that cannot be described simply by marking multiple boundary edges as slope-defining.

• Start a roof with Architecture > Roof > Roof by Footprint.
• Sketch the roof boundary as usual.
• On the Draw panel, select Slope Arrow.
• Draw the arrow in the intended uphill-to-downhill direction. The arrow tail typically represents the higher end, while the arrow head represents the lower end.
• Select the slope arrow and define its values in the Properties palette.

The most important slope-arrow settings are Height Offset at Tail, Height Offset at Head, and either the Slope or Level Offset control, depending on the roof configuration. These parameters let you define a roof plane using actual elevations rather than relying only on a pitch value.

For example, if a rectangular roof must slope toward a rear gutter:

• Set the high-side tail offset to the required elevation.
• Set the low-side head offset to the gutter elevation.
• Confirm that the arrow runs perpendicular to the intended drainage edge.
• Finish the roof sketch and inspect the result in a 3D view and an elevation or section.

A key best practice is to avoid mixing conflicting slope controls. If a slope arrow is driving the roof plane, review the boundary lines and remove Defines Slope from edges that should not create additional roof planes. Leaving slope definitions active on multiple sketch lines can produce unexpected ridges, valleys, or warped geometry.

Use slope arrows particularly well in these situations:

• Single-direction drainage: Flat or low-slope roofs draining to one gutter, scupper, or drain line.
• Asymmetric roof forms: Roofs where the high and low points do not align with standard footprint edges.
• Renovation work: Existing conditions requiring a new roof to match surveyed elevations.
• Coordination-sensitive drainage: Roofs where slopes must align with parapets, overflow scuppers, drains, or tapered insulation design.

After creating the roof, verify the geometry instead of assuming the arrow produced the intended result. Create a section perpendicular to the slope arrow and check the elevation at both ends. In a 3D view, turn on shadows or use a consistent visual style to make subtle low-slope changes easier to read. You can also place spot elevations at critical corners, drain locations, and parapet tops to confirm that the modeled design communicates the required drainage strategy.

Remember that a slope arrow controls the roof’s geometric plane; it does not automatically resolve every detailing requirement. Coordinate roof drains, crickets, parapet heights, insulation build-up, structural slope, and membrane drainage with the appropriate disciplines. For advanced documentation workflows, reliable Revit tools and learning resources are available through NOVEDGE’s Autodesk Revit collection.

A disciplined slope-arrow workflow creates roof geometry that is easier to coordinate, easier to document, and much less likely to cause costly field questions about where water is intended to go.

You can find all the Revit products on the NOVEDGE web site at this page.