Roof¶
Step 3 puts the roof on the building. In the main panel you pick one of five shapes; pitch, overhang and special options are set on the right in the parameter panel.
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¶
For the gable, hip and shed roof you set the roof pitch: 5–75° — for the shed roof 1–60°. Flat roof and "No roof" have no pitch.
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 standard ridge = yes: 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). A roof terrace comes out of that: give the area its own roof, set the shape to Flat and switch on "Walkable roof".
| Value | Range |
|---|---|
| Shape | Flat, Gable, Hip, Shed |
| Pitch | 0 to 75°, shed roof 0 to 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¶
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, choose the first tile, Walkable roof, before Flat roof. This applies to the main roof, leftover areas and extensions. The area is built as a floor slab without a roof overhang; stairs up are possible. The railing choices None, Closed, Balusters and Battlements form a square, with each name below its icon frame. None leaves the slab without a railing. Enabled railing types per edge still take precedence; turn that option off for a completely railing-free area.
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 solidly to the floor slab beneath it (one printed part); where it meets the exterior wall a fine print tolerance of 0.3 mm remains so the part doesn't jam during assembly (in the monolith model it sits flush).
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.
Standard ridge — 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 "standard ridge" toggle.
- standard ridge = yes (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.
-
standard ridge = no: 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.
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.
As long as something is missing, the roof stays as it is
A group that is still incomplete — a single line waiting for its second reference line, say — does not change the roof. Only a complete pair rebuilds it. The hint below the window tells you what is missing, and a dot on the Roof 1 … Roof n tab shows which roof is still waiting for its picks. As long as one roof is unfinished, no roof is built at all — not even the ones already finished.
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.