Adding relations

Adding relations

Goal: link tasks together, so that a task starts only when the work before it is finished, and add a waiting time (lag) between them where needed.

When you need this

Without relations the app does not know that the bricklayer can only start once the foundation has been poured. Every task then starts on the project start and the finish date means nothing. A relation records that order. The first task is the predecessor, the second the successor.

You add relations when you build a schedule, when a task is added, or when two jobs turn out to depend on each other after all. A lag is waiting time between two tasks, such as concrete that has to cure or a floor screed that has to dry.

The default relation is FS (Finish-Start): the successor can only start once the predecessor is finished. The app also knows SS, FF and SF, which tie a start or finish to a start or finish; with SS (Start-Start), for example, the plastering can only start once the building services have started.

Not sure which type you need? Below the type choice, a sentence with the real task names explains it, for example Metselwerk can only start once Fundering has finished. Choose another type and the sentence changes with it. You see it in the Relation type window, in the Dependencies block and in the Predecessors or Successors column.

Steps

There are four ways to add a relation. They create the same relation; pick whatever suits your situation best.

Linking two selected tasks

Useful when you work in the task list.

1. In the task list, click the task that comes first: the predecessor.
2. Hold Ctrl (⌘ on a Mac) and click the task that comes next: the successor.
3. Choose Home › Tasks › Link ▾ › Link selected tasks. The same button is also on Planning › Relations.

The app creates a Finish-Start relation without lag. You see it as an arrow in the Gantt and in the Predecessors column; a notification only appears if the app refuses the relation. The button only works with exactly two selected tasks.

Drawing a relation in the Gantt

Useful when you add many relations in a row.

1. Choose Home › Tasks › Link ▾ › Draw relation. Above the schedule the notice Link mode: drag from one bar to another in the Gantt to create a relation. Press Esc to stop. appears.
2. Press on the predecessor's bar and drag to the successor's bar. A dashed line with an arrow follows you.
3. Release. A small window Relation type appears with the type (FS by default) and a box for the lag.
4. Change the type or lag if needed and press Enter, or click outside it. The relation is created.
5. Add the next one straight away: the mode stays on. You stop with Esc, with the Stop button in the notice, or by choosing Draw relation again.

If you press Esc in the Relation type window, nothing is recorded. For a single relation you do not need to turn the mode on: hold Shift while you drag from bar to bar. Start relation from here in a bar's right-click menu turns link mode on; you still do the dragging yourself. On the Table tab, without a Gantt, Draw relation is disabled.

Adding a relation in the Properties panel

Useful when you are looking at one task and want to add its predecessors or successors.

1. Select the task. The Properties panel is on the right; if you do not see it, turn it on with View › Panels › Properties.
2. In the Dependencies block, click Add relation.
3. Leave the direction on Predecessor if the other task comes first, or choose Successor.
4. Type part of the other task's name. Pick the right one with the arrow keys and Enter, or click it.
5. Choose the type (FS by default) and fill in a lag if needed.
6. Press Enter or click the tick (Create relation).

The task's relations are then listed in Dependencies, each with the other task's WBS number, the type and the lag.

Typing relations in the Predecessors column

Useful when you work fast with the keyboard and know the WBS numbers.

1. Click the + on the right of the task list header (Add column) and, under Relations, choose the Predecessors column. The Successors column works the same way.
2. In the Predecessors column, click the cell of the successor.
3. Type the predecessor's WBS number, a space and the type, for example 2.6 FS. Put a lag straight after it: 2.6 FS+1d. Separate several predecessors with a semicolon or comma: 3.1 FS; 3.2 SS+2d.
4. Press Enter.

What you type replaces the whole cell. If there are predecessors in it already, type them too (see the pitfalls). If you press Enter or F2 in the cell instead of typing, an input opens that keeps the existing relations: you search for a task by WBS number or name, and choose the type and lag for each relation.

Setting or changing a lag

You type a lag in the box next to the type, with each of the ways above. You change an existing lag in Dependencies: click in the lag box, type the new value and press Enter.

• 3 or 3d: 3 work days. A weekend does not count. The app shows +3d.
• 3ed: 3 calendar days. The weekend does count, as with concrete that also cures on Saturday and Sunday.
• -1: a negative lag (lead). The successor may start a day earlier, so the tasks overlap.
• 4h: 4 working hours; the app shows it as +4h. If the predecessor is a day task on a calendar without working-time blocks of its own, such as the standard calendar, the app converts this to whole work days, rounded to the nearest whole day: 4h then acts as 1 day, 2h as 0. On a calendar with working-time blocks of its own, or after an hour task, the lag counts exactly in hours.
• 50%: half the predecessor's duration.

Example: the foundation concrete has to cure before the bricklayer can work on it, so Pour foundation → Foundation brickwork gets an FS relation with lag 3. If the pour is on Friday 18 June 2027, the brickwork starts after Calculate on Thursday 24 June: Monday to Wednesday is waiting time. With 3ed the weekend counts and the brickwork starts on Tuesday 22 June.

Finally: recalculate

A new relation does not move any bars yet; the status bar says Out of date — recalculate (F5). Press Calculate (F5), for example through Home › Schedule › Calculate. Only then do the successors get their new dates. If you want the app to do this for you, turn on Calculate automatically under Settings › Project › App settings, tab Planning.

Pitfalls and what the app does

Reversed order. With Link selected tasks the order in which you click counts, not the order in the list. If you click the later task first, the relation is the wrong way round. Delete it in Dependencies with the bin icon and add it again.

Typing in the column wipes what was there. If the cell holds 3.4 FS; 3.2 FS and you type only 3.2 FS, the relation with 3.4 is gone, without a message. Type all predecessors, use Enter or F2 to add to them, or undo with Ctrl+Z.

A cycle. If you add a relation that leads back to a task earlier in the chain, the schedule could never start. The app refuses such a relation: This relation would create a cycle in the schedule (…) and was not created, with the tasks of the cycle in brackets. First delete the relation that closes the cycle.

A task to its own phase. A relation between a task and the summary task it sits under is not possible. The app says A relation between a task and its own (grand)parent summary task is not allowed.

Duplicate. If the relation already exists, the app says That relation already exists and nothing changes.

Shorter messages in the column. The Predecessors column gives the same refusals with a shorter text under the cell: This change would create a cycle in the schedule., This relationship already exists. or A task cannot have a relationship with its own summary task. If you type only a WBS number, such as 3.1, the type is missing and the cell says Use a value such as 1.2 FS+2d. The cell stays open; correct the input or press Esc to cancel.

No half days of lag. A lag in days is always a whole number: 1.5 becomes +2d, and an hour lag after a day task on a calendar without working-time blocks of its own is rounded to whole work days. Unreadable input, such as a word, is not saved: the box jumps back to the previous value.

See also

• Critical path and float: what the app calculates from your relations, and why a task becomes critical.
• Relations and lag: what the four kinds of relation and a lag do to the dates.
• Tracing a path: bringing the chain of predecessors and successors into view.
• Task dialog and properties panel: the fields for relations and lag in the panel and the dialog.
• Refurbishment & Extension of a Family Home: a chain of finish-to-start relations with one start-to-start (walls and roof, lag of 2 days) and one finish-to-finish (tiling and painting, lag of 1 day).