Roof¶
Step 3 puts the roof on the building. Choose its shape in the main panel; set pitch, overhang and special options in the parameter panel on the right.
Selecting the Flat roof tile starts with a 0.50 m overhang. Set the overhang to 0 to switch automatically to a parapet. This applies to the main roof, independent annex roofs and secondary roofs on storey setbacks. Selecting Flat roof again returns to a 0.50 m overhang; loading a project preserves its saved dimensions.
The facade editor in Floor plan, roof-edge options in Roof, window details in Extras and shutters on openings are explained in Facades and window details.
Main and independent annex barrel roofs do not allow an additional eaves cornice. Switching to a barrel roof turns off an existing cornice selection while preserving the building and its other facade settings. The same rule applies to the AI interface without a confirmation question. Annexes under the main roof follow its rule; independent roofs of other shapes keep their permitted cornice choice.
Barrel-roof arch rise¶
Explicitly selecting Barrel roof starts the existing dimension control at 50% of the actual roof-base width, forming a semicircle. You can reduce the rise to 12.5% inclusive. The dimension icon shows the vertical distance at the middle of the arch from the horizontal line joining the eaves to the crown. The eaves stay fixed while the crown lowers. At a width of 10 m, 30/40/50% gives a rise of 3/4/5 m. Loading, changing the width and recalculating preserve the saved percentage. There is no separate variant or radius selector. An independent annex barrel roof has the same control for its own width; annexes under the main roof follow the main curve. Overhang is fixed at 0.10 m. Roof skin, wall connection and roof-height end windows follow the same circle. The separate barrel dormer keeps its own setting.
Choosing a roof shape¶
| Shape | Description |
|---|---|
| Flat roof | A horizontal roof slab. Preselected by default. |
| Hip roof | Sloped on all sides. Individual edges can be turned into a gable — see Gable edges on a hip roof. |
| Shed roof | A single sloped face. |
| Gable roof | Two sloped faces, ridge in the middle, vertical gables. |
| No roof | The building ends flat at eaves height — no roof shell, no gable. |
Shed roof on the T-plan
For the T-shaped floor plan the shed roof isn't available.
Pitch¶
Gable roof: −30° to −5° or +5° to +75°. Height may limit the range. Negative angles lower the centre between fixed eaves; drainage is internal.
Hip roof: +5–+75°. Mono-pitch roof: +1–+60°. Both asymmetric gable slopes remain positive (+5–+75°).
Pitch and height limit each other
The pivot point of the roof pitch lies on the inner edge of the exterior wall. At the outer edge the underside of the roof is therefore 0.40 m · tan(pitch) lower — with too little height the roof would cut below the floor. The app doesn't allow that in the first place and limits both directions automatically: the maximum pitch follows the available height, the minimum height follows the pitch you have set.
| Available height | Pitch up to |
|---|---|
| 0.3 m | 36° |
| 0.4 m | 45° |
| 0.5 m | 51° |
| 0.7 m | 60° |
| 1.0 m | 68° |
| 1.5 m | 75° (end of the slider) |
What counts is, on the main roof, the ceiling height of the top floor, on the extension roof its eaves height, and on the secondary roof the floor-to-floor height (ceiling height plus slab thickness). Flat roof and "No roof" are exempt.
Asymmetric gable roof¶
Only for rectangular plan + gable roof and Custom ridge direction = off: the "asymmetric gable roof" toggle in the parameter panel gives you two separate pitches — one per roof face. The ridge then shifts out of the middle toward the steeper side. The two pitches must differ.
Roof overhang¶
The overhang ranges from 0 to 2.5 m. Two modes:
- One value for all edges — toggle "var. roof overhangs" off (default).
- Per edge — toggle "var. roof overhangs" on: you give each outer edge or edge group its own overhang. Each row shows the floor plan in miniature beside it, with the edge in question highlighted in yellow. At inner corners (valleys), converging edges automatically share one value.
Bearing surface at overhang 0
With the overhang set to 0, the eaves no longer end at the roof pitch but get a horizontal surface 10 cm wide, flush with the front face of the wall — so it does not project. It serves as an additional bearing: previously the roof rested on a single edge here. This applies to all roof shapes and only at overhang 0; as soon as you set an overhang, the eaves stay as before.
Gable edges on a hip roof¶
A hip roof is hipped on all sides. You can exempt individual edges: below the roof shape a switch "Edge 1", "Edge 2", … appears for every selectable edge.
The hip is omitted at this edge — a gable is created there, turning the roof into a gable roof on that side. Only edges with a triangular roof face can be selected.
On a rectangle these are the two short sides; the long sides carry a trapezoidal face and are therefore not offered. Which edges are selectable is computed by the server from your outline — the list changes as soon as you change the floor plan.
The roof gets bigger, not smaller
Instead of the hipped triangle, the two neighbouring faces now run through to the gable wall. In the measured example (rectangle 10 × 8 m, pitch 25°) the volume of the roof shell grows from 32.68 m³ to 33.60 m³.
On L, T and U the whole roof is rebuilt
Gable edges exist for all floor plan shapes as well as on extensions and secondary roofs. On L, T and U you should know what the switch does there: without a selected edge the hip roof is made of two or three rectangular tracts that cut into each other. As soon as you turn one edge into a gable, the roof is rebuilt as one roof over the entire outline — and roof faces far away from the selected edge change too. Measured: on an L only 2 of 6 roof faces stay unchanged, on a T 1 of 7, on a U 3 of 8. The ridge height stays the same; the ridge line may run further than before. Deselect the edge and the original roof is back unchanged.
The choice belongs to this outline and this roof shape
If you change the floor plan shape or the roof shape, the edge selection is gone and you choose again. That is deliberate: edge 1 on an L floor plan means a different edge than edge 1 on a rectangle — the old number would point at a side nobody selected.
Secondary roofs (free floor plan only)¶
If your building has a leftover area that the main roof doesn't cover — a bay window or a lower extension, say — you use the "Roof 1", "Roof 2", … buttons to choose one of two options per area: the floor slab stays visible, or the area gets a roof of its own (shape, pitch and overhang separate from the main roof). For a roof terrace, select the “Walkable roof” icon directly under Roof surface for that area’s own roof.
| Value | Range |
|---|---|
| Shape | Flat, Gable, Hip, Shed |
| Pitch | Gable −30…−5° or +5…+75°; hip 0…75°; mono-pitch 0…60° |
| Overhang | 0 to 2.50 m |
| Count | at most 50 per building |
The eaves of a secondary roof sit on the top edge of the floor slab of its area. Roof windows and dormers can be placed on secondary roofs too.
Walkable roof — the roof terrace¶
For the walkable main roof, the railing choices remain visible at all times. Roof overhang and eaves cornice are not offered here.
The height described above applies to non-walkable secondary roofs. A walkable area is generated as a floor slab directly on top of the walls, with the regular slab thickness and matching wall-to-slab connection profiles. On a leftover area it remains part of the existing floor slab; no additional roof slab is placed above it. The same construction principle applies to walkable main and extension roofs.
Under Roof area, Walkable roof comes before Flat roof, for the main roof, leftover areas and extensions. It forms a floor slab without roof overhang; stairs up are possible. No railing, Closed, Balusters and Battlements use square icons with labels below. No railing creates a continuous parapet as on a flat roof without overhang and switches off differing railing types per edge. The roof edge stays clear alongside higher adjoining walls. The parapet follows only the free edges. An extension’s own roof slab and parapet remain available even while the main roof selection is incomplete.
When a railing is selected:
The walkable area gets a railing along all free outer edges — either closed, as a baluster railing like on balconies and terraces, or with battlements, which exist only here. At very small scales the merlons automatically become fewer and wider so they stay printable. The railing is fused to the floor slab beneath it as one printed part. Closed and picket railings end 5 cm before the front face of a higher adjoining wall. The gap is measured perpendicular to the wall; the end face is parallel to it. This building-space distance is independent of print scale. The slab retains its wall contact and any applicable storey band remains. Attika and battlements retain their own connection profiles and the existing 0.3 mm print clearance (flush in the monolith model). The cantilevered ends and teeth of the battlements also retain this print clearance from the actual higher wall when it continues outside the local roof outline. The free cantilever remains intact.
Only the battlemented parapet projects: it stands 0.40 m in front of the wall face and rests on a continuous 45° slope. Merlon caps and crenel sills fall away 30° towards the outside. The heights are measured on the inner face — 0.90 m to the crenel sill, 2.10 m to the top of the merlon. Where the parapet meets a wall rising above it, the projection returns on a mitre.
Battlements on selected edges only¶
The toothed crown known from castles need not run all the way around. Below the railing choice sits the switch "Choose railing type per edge". With it on, the outline of the walkable area appears and you click the edges that should carry battlements — they turn yellow. All remaining edges get a closed parapet. A second click takes an edge back again. To the right of the outline it says how many edges carry battlements and how many do not.
At the corner between a battlemented edge and a parapet edge, the battlement runs around the corner and ends in line with its own inner face — with a right angle that is 0.25 m further. This way the corner forms completely instead of breaking off at the edge. At oblique corners this piece becomes longer by itself.
Custom ridge direction — choose ridge and eaves yourself¶
For the gable roof and shed roof over a standard floor plan (rectangle, L, T, U) the parameter panel has the "Custom ridge direction" toggle.
- Custom ridge direction = off (default): ridge and eaves positions are set automatically — on the gable roof the ridge runs parallel to the longer building side, on the shed roof the face slopes down toward the preset eaves side. You don't need to choose anything else.
-
Custom ridge direction = on: you set the position yourself. An outline window appears in which you click the relevant edges:
- Gable roof: Pick two opposite parallel edges — the ridge runs between them. Any further parallel edge you pick trims the roof surface (gutter) but does not move the ridge.
- Shed roof: Pick the eaves edge (the low side of the roof). Any further parallel edge trims the roof surface (gutter or ridge).
Wherever you pick no edge, the roof runs out to the outline. If on a simple rectangle you pick two non-opposite edge directions, they intersect automatically into a T-roof.
Standard floor plan only
On the free floor plan you always choose the ridge reference edges via the outline window — there is no standard-ridge toggle there. For the T-plan the shed roof isn't available.
A connected main-roof area¶
On a free floor plan, the selected main-roof area and every annex assigned to that roof must form one connected outline. Touching only at a corner is not enough.
If the areas are initially separate, the roof-area selector shows a warning and keeps the existing remaining areas available. Select an adjoining remaining area if it should provide the intended connection. Only a connected selection can be accepted. Assigned annexes are fully included in the main roof; a connecting remaining area is added through your actual area selection.
Ridge reference edges on the free floor plan¶
On the free floor plan — and likewise on every secondary roof on a leftover area — you choose the ridge reference edges in the outline window. Your picks form groups, and each group is a roof part of its own. In the window the groups get different colors so you can see what belongs together.
- The first two edges form the main group — the main ridge runs between them.
- Every further edge parallel to them sets a gutter. It limits how far the main roof is carried down at that point, but does not move the ridge. Wherever you set no gutter, the roof surface runs on down to the lowest eaves — that creates a covered outdoor area.
- Edges of a different direction form a cross gable. A cross gable has exactly two reference lines; if you pick a third edge in its direction, that starts a new cross gable. So gutters only exist in the main group.
- Instead of a second edge you can click a corner point. A dashed, imaginary reference line then runs through it parallel to the first edge — handy when there is no suitable edge opposite the cross gable. Every cross gable may have its own corner point.
A cross gable must not rise above the main ridge
All roof parts have the same pitch — so the distance between the two reference lines alone decides the ridge height. If a cross gable spans further than the main roof, its ridge would sit higher; the app rejects that and tells you both spans.
Incomplete ridge references
An incomplete ridge-reference group, such as a single line without its second reference line, blocks calculation of the corresponding main roof. The main roof can be calculated only once all its required groups are complete. The hint below the outline window identifies the missing selection; the dot on the Roof 1 … Roof n tab shows which roof is still waiting. Wall-flush cross gables also require a main roof that can be calculated. Independently completed secondary and annex roofs remain available.
What you see in the window
Ridge, hip, valley and verge lines are drawn in live as thin white lines — solid for the ridge, dashed for hip, valley and verge. They come from the roof as actually built, not from a sketch. Sections marked red lie against an exterior wall running up past the roof: no eaves may drain there, so the eaves are interrupted at that point and a cross gable is formed above the wall section.
Eaves and ridge
Roof-related terms — eaves, ridge, verge, knee wall — are in the Glossary.
Wall-flush cross gable¶
Cross gables are available on suitable gable, mono-pitch and hip roofs. On a mono-pitch roof the cross gable has a saddle roof at the main pitch, which is fixed here. On a mansard gable or hip roof, the cross gable also has a mansard break with 75° below and 30° above. The option is absent on flat, sawtooth and barrel roofs. The front remains flush with the wall and the crest stays within the permitted roof height.
Place it on a blue eave edge in the plan. It snaps to the eave midpoint and shows live clear distances to the outer wall edges. Use + to add more. Width follows from height and pitch. Click the width dimension to enter it.
Outer roof edges must stay within the perpendicular wall boundaries. Keep 0.25 m clear in plan from other cross gables, eave corners, dormers and roof windows. There is no lateral eave overhang; the front verge ends exactly at the main eave front edge. There is no separate overhang control.
The outline also appears under Extensions and fixtures and Openings. Normal facade windows can be placed in the raised wall, with height limited by the actual roof. Export uses the normal roof-face, connector and print-bed splitting for the selected construction mode.
In the roof plan under Openings → Roof, beside the roof windows, select the Cross-gable window icon and place a window on the cross-gable front. The usual window controls set sill height, height and width. Tall windows starting lower down and extending into the cross gable also appear in the roof plan. Each remains one continuous wall opening; no separate opening is needed for the roof area.
Set the mansard Break height beside a section icon showing its vertical dimension. The icon and slider share one row. The perspective Cross gable icon activates editing; its controls appear only after activation.
Print orientation of the mansard hip roof¶
For a mansard hip roof, the lower closed ring rests on the print bed with its receiver side toward the upper hipped roof facing downward. Its original upper edge is trimmed vertically by 96 mm in building dimensions. This building-space value stays fixed and is converted proportionally for every print scale. The prescribed bed orientation is retained through texturing and STL/3MF export. The lower ring and upper roof are separate print parts.
Parapet on a walkable flat roof¶
The parapet is available on walkable main roofs, leftover areas and separate extension roofs. It is fused to the floor slab with the normal wall-to-slab connection. The wall is 30 cm thick and rises 20 cm above the roof; the cover adds 5 cm, projects 5 cm on each side and returns to the wall at 45° underneath. Wall texture reaches the underside of the cover.
The rendered roof carrier and parapet wall use the selected exterior-wall colour throughout, including storey and extension overrides. The coping remains its own separately coloured material part. In BM, the inner horizontal roof surface is a separate material layer with 0.6 mm printed thickness at every BM scale, in the selected floor-slab colour. These material parts belong to the same roof print object; existing roof openings stay open. MM keeps the roof fused. HM retains its existing single-colour roof output.
Sawtooth roof¶
MM: The entire sawtooth roof is one connected print piece without panes. Its L-shaped sections are fused at their joints. BM and HM retain the separate plug-together L modules. The glazing choice for other windows and doors still applies. For printing, the roof rests on its side sawtooth cross-section.
BM/HM: The lower outside end of the last short glazing leg is bevelled at 45° to the horizontal of the print bed in this orientation. The supporting side walls follow the same end contour with 0.15 mm printed clearance normal to the mating face; the roof overhang remains 0.10 m. If an end module is too short at the selected scale to keep a post connected to the frame, calculation reports the geometric conflict and does not export a detached post.
BM/HM: The sawtooth roof uses only the structure of its profile and receives no additional surface texture, including on the glazing frame. The dividing posts are fused with the frame and roof module. When glazing is included in the export, each L module has a separate continuous pane. Its recess is near the inner face of the frame, and the pane is inserted from inside. On the print bed, the outer glazing-frame face lies flat and the solid roof sheet stands upright. The pane recess is therefore accessible from above. This applies to main roofs and independent annex roofs.
BM/HM: The pane perimeter uses the existing window-frame retaining profile. It engages behind the groove lip; the receiving groove is enlarged by 0.15 mm at print scale, normal to the mating faces. The continuous pane is pressed in from inside. Wall tongues remain integral with the supporting walls and fit the roof grooves, including at the joints between L modules.
BM/HM: At the free roof end, which is at the top in the print orientation, wall tongues and their receiving grooves are shortened by 15 cm in building dimensions along the roof slope. Roof height and part thickness remain unchanged.
BM/HM: If separate windows are also exported, the sawtooth-roof panes are independent glass parts in the same window print output. Without separate windows, they receive their own glass-only output.
BM/HM: The connection between adjacent L modules follows the raised reference tongue contour. The tongue and the short leg’s end face belong together. Across the roof width, the tongue is divided into equal sections; fixed-width interruptions leave supporting bridges in the mating part. Pockets are enlarged by 0.15 mm at print scale on every mating face, including both ends.
Battlements automatically inherit the facade texture of their storey or annex, including in print exports. Other railing types retain their own surface.