I recently had a client who had issues with a Revit roof design containing gaps. The existing roof had two slopes creating the gap. Below are screenshots of the gap, both a 3d and a side view.

Revit roof design - 3D view Revit roof design - 2D view

I’m sure there are many solutions, but the first one that sprang to mind was using roof/floor Modify Sub element tools.

Revit roof design - Modify Tools

The Modify Sub element tools can only be used when a roof or a floor does not contain a slope.

So, the first step in the solution was to go to roof plan view and create a flat roof that fits into the gap. Once you have finished creating the sketch, you need to make sure no slopes exist on any of the three sides of the filler roof.

Revit roof design - Slopes

Once created, select the roof and click the Modify Sub elements tool in the Shape Editing contextual panel on the ribbon. Three green grips will appear on the corners of the roof.

Revit roof design - Modify Sub Elements

Select the two grips on the eave side of the roof. Drag each – one at a time – downward and snap to the existing roof to close the gap. You might also need to just adjust the angle of the surface pattern by Tab Selecting a line on the roof and rotating the surface pattern line to match the existing roofs pattern.

Revit roof design - Grips

Here is a screenshot of the completed roof filler linking the existing two roofs together.

Revit roof design - Filling Gaps