# Start a house or building

Make a house or building project with levels, then add storeys, stairs and a roof.

A house or building project has one level for each storey. Each level starts with a closed loop of external walls. You then divide each level into rooms.

KerfCraft makes a model for design. It does not check a design against Building Regulations or planning rules. The stair checks and house notes are advisory only.

## Make the project

1. Click **File ▾**.
2. Click **New ▸ House / building…**.
3. Type a **Name** and click **Create**.
4. In **New house / building**, type the sizes.
5. Click **Create**.

The sizes in the dialog are:

| Field | Default | What it sets |
| --- | --- | --- |
| **Footprint width (mm)** | 8000 | The outside width of the external walls |
| **Footprint depth (mm)** | 10000 | The outside depth of the external walls |
| **Storeys** | 2 | The number of levels |
| **Storey height, floor to floor (mm)** | 2600 | The height from one floor to the next |
| **Ground floor level (mm)** | 0 | The finished floor level of the ground floor |
| **External wall thickness (mm)** | 300 | The external walls. 300 gives a cavity wall, 215 a solid brick wall |

The levels get the names Ground floor, First floor, and so on.

## Divide a level into rooms

1. Click **Plan** or **Split** in the main view.
2. Select the level in the level list of the plan view.
3. Click **✎ Draw walls**.
4. Draw a wall from one external wall to another. Press **Enter** to finish.

Each closed area becomes a room. For the full drawing steps, see [Draw walls and rooms in the plan view](/docs/how-to/rooms/draw-walls-and-rooms/).

The assistant can also lay out the full house from a brief. For example:

```text
Lay out a two-storey house, 8 m wide and 10 m deep: living room, kitchen, WC downstairs, three bedrooms and a bathroom upstairs.
```

It makes the walls, rooms, doors, windows, a stair and a roof. You can edit all of them after.

## Work with levels

The **Model** panel shows each level with the items on it.

- To make a level active, click its row. New items go on the active level, and the plan view shows it.
- To add a storey above the top level, click **+ level**.
- To change the name or floor level of a level, click **✎** on its row.
- To delete a level and everything on it, click **🗑** on its row. You can undo this.

The level list in the 3D view and the plan view also selects the active level. A second list sets how the other levels show in 3D: **others: ghosted**, **others: shown** or **others: hidden**. The plan view shows the walls of the level below as faint outlines, unless that level is hidden.

## Add a stair

1. Select the lower level.
2. Click **Plan** or **Split** in the main view.
3. Click **+ Stair** in the plan view. This button shows only when there is a level above.

KerfCraft adds a straight stair up to the next level, with one corner at the centre of the plan view. The floor above gets a stairwell opening. You can drag the stair in the plan.

To change the stair, select it and edit its **Parameters** in **Properties**:

- **shape**: straight, L (quarter landing), U (half landing) or winder.
- **turn**: left or right, as you walk up.
- **width**, **going**, **risers** and **nosing**. With **risers** at 0, KerfCraft uses the fewest risers that give a rise of 220 mm or less and a pitch of 42° or less.
- **headroom**: this sets the size of the stairwell opening.
- **construction**: **architectural** shows the stair but keeps it out of the cut list. **timber** puts the treads, risers, strings and landings in the cut list.

**Properties** shows the derived sizes, for example the rise and the pitch. It shows a warning when a value is outside common UK guidance for private stairs. These checks are advisory. A timber stair does not include landing bearers, trimmers, newels or balustrades.

## Add a roof

1. Press Esc until nothing is selected. The **Properties** panel shows the project settings.
2. In the **Roof** row, click **Add roof…**.
3. In **Level**, select the level that the roof sits on. The top level is the default.
4. Select the **Shape** and type the **Pitch** in degrees.
5. Click **Add roof**.

The fields are:

- **Shape**: **Gable**, **Hip** or **Lean-to**.
- **Pitch**: the angle from horizontal, in degrees. The default is 35.
- **Overhang**: the eaves and verge overhang past the outer wall faces. The default is 300 mm.
- **Thickness**: the rafters and the covering, measured square to the slope. The default is 250 mm.
- **Ridge**: the direction of the ridge, **East–west (x)** or **North–south (y)**. The default is along the longer side.
- **Ceilings**: **Flat** keeps flat ceilings with a loft above. **Sloped** opens the rooms below to the roof.
- **Collar**: for sloped ceilings, the height of a flat ceiling across the top. Leave it empty to slope up to the ridge.

You type lengths in the display unit of the project. The roof sits on the external walls of the level, and it changes when the walls change. A roof is not in the cut list.

## Change or remove a roof

1. Select the roof in the 3D view or the **Model** panel.
2. In **Properties**, find the **Roof** row and click **Edit roof…**.
3. Change the values that you need.
4. Click **Apply**.

To remove the roof, delete it.

## Related

- [Add doors and windows](/docs/how-to/rooms/add-doors-and-windows/)
- [Make drawing sheets](/docs/how-to/rooms/make-drawing-sheets/)