Calendar Setup and Holidays
Last reviewed 9 September 20261,927 words9 min read
Working days, Ramadan, monsoon, summer break, planned shutdowns
🟩 In one line — A Gulf project needs five to seven calendars — a 6-day site calendar with summer hours and Ramadan hours as date exceptions, a 7-day 24-hour calendar for curing and continuous work, a 5-day office calendar for design and approvals, and one per overseas vendor — built before the first activity is typed, with holidays entered as exceptions for every year of the project and the Hijri dates confirmed annually.
👤 Who this is for — Juniors setting up a project, and mid-level planners inheriting a file where every activity is on "Standard 5 Day Workweek". You should know how P6 converts durations to hours.
First, let's be honest about why this page exists
Calendars are set up in the first hour of a project by whoever is in a hurry, and never looked at again. Then two years later someone notices the concrete cures over Fridays it wasn't given, the Engineer's 14-day review periods were counted on the site's 6-day week, and August had ten-hour days on the roof. None of these show up as errors. They show up as a programme that is consistently, quietly, optimistic. Calendar mistakes don't break the schedule; they bias it, and always in the same direction.
🟨 The standard — what "good" looks like
| Reference | What it requires |
|---|---|
| GAO Schedule Assessment Guide, Best Practice 4 | Durations realistic against the calendars actually assigned; calendars reflect real working time and holidays |
| AACE RP 32R-04 | Duration basis includes the calendar assumed |
| PMI Practice Standard for Scheduling | Calendars defined for project, resources and activities; documented in the schedule model |
| FIDIC 1999 Cl 8.4(c) / 2017 Cl 8.5(c) | Extension only for exceptionally adverse climatic conditions — normal seasons are yours to plan for |
| NEC3/NEC4 Cl 60.1(13) | Weather is a compensation event only beyond the 1-in-10-year data; the rest sits in your calendar and allowances |
| Ministerial midday-break rules (UAE MoHRE, KSA MHRSD, Qatar MoL) | Mandatory break for outdoor work in summer months; windows differ by country and are re-issued yearly — confirm the current year |
🟢 Rule to remember: put lost hours in the calendar, lost efficiency in the rate, and never the same loss in both.
How it actually works
Where. Enterprise → Calendars. Three types: Global (shared across the database), Project (belongs to this project, travels in the XER), Resource (per resource, used by resource-dependent activities). Build project calendars, not global ones, unless you own the database — global calendars changed for your job change everyone's.
What's inside a calendar. A standard workweek (which days, which hours), exceptions (specific dates made non-work, or given different hours), and Time Periods (hours per day/week/month/year). The Time Periods matter: Admin → Admin Preferences → Time Periods has a checkbox to use each calendar's own hours for duration conversion. Tick it, or a 14-day activity on a 10-hour calendar will display as 17.5 days for anyone whose default is 8 hours (see hours-per-day-and-duration-display).
The typical set for a Gulf building or plant project:
| Calendar | Week | Hours/day | Used for |
|---|---|---|---|
| Site — 6 day | Sat–Thu, Fri off | 10 (07:00–18:00, 1 h break) | Most construction activities |
| Site — 7 day / 24 h | All days | 24 | Curing, continuous pours, hydrotest holds, procurement lead times, shipping |
| Office — 5 day | Mon–Fri (or Sun–Thu; match the Engineer) | 8 | Design, submittals, Engineer's reviews, authority approvals |
| Shutdown / T&C — 7 day | All days | 20–24 (two or three shifts) | Commissioning blitz, tie-ins, turnarounds |
| Vendor — per country | e.g. China 6-day, Europe 5-day | 8 | Fabrication; carries that country's holidays (Chinese New Year, August in Europe) |
| Ramadan variant (only if separate) | Sat–Thu | 8 | See below — usually better as exceptions |
Five to seven is normal. Fifteen is a sign the previous planner made a calendar every time a subcontractor sent a programme.
Summer hours: exceptions, not a separate calendar. The midday break removes roughly 2.5–3 hours in the UAE (12:30–15:00) and KSA (12:00–15:00), and about 5.5 hours in Qatar (10:00–15:30) from an outdoor day between mid-June and mid-September (windows differ: UAE and KSA mid-June to mid-September; Qatar starts 1 June — confirm each year). Two ways to model it:
- Separate summer calendar assigned to outdoor activities. Simple, but when an activity slips out of summer it keeps the short hours, and when one slips into summer it doesn't get them.
- Exceptions in the main site calendar: each summer date given 8.5 hours instead of 10. Date-driven, so any activity that lands in the window is affected automatically, whatever it is and whenever it moves.
Use the second. Enter the exceptions for every summer in the project's life on day one. It takes twenty minutes.
Ramadan. Reduced working hours (typically two hours less) for the month, then Eid al-Fitr. Model the hours as date exceptions in the site calendar, the Eid days as non-work exceptions. The dates are Hijri and move about eleven days earlier each Gregorian year — enter approximate dates for future years and mark the exception description "approx — confirm". The real loss is usually the two weeks after Eid when labour is still returning; that's a productivity factor, not a calendar entry.
Public holidays. Eid al-Fitr and Eid al-Adha (Hijri, moving), Islamic New Year, National Day (UAE 2–3 Dec, KSA 23 Sep, Qatar 18 Dec), plus country-specific days. Enter them as non-work exceptions for every year. Sites in the Gulf typically lose 10–14 days a year to public holidays; if your calendar shows fewer, something is missing.
Client shutdowns and site-specific closures. Plant turnarounds, exam periods on a school site, event blackout dates near a venue, Formula 1 week in Abu Dhabi if you're on the island — all exceptions in the site calendar, all in the basis memorandum.
Weather calendars. Gulf rain is a downtime allowance, not a calendar. Oman's Khareef in Dhofar, Indian monsoon, Southeast Asian wet seasons are calendar-scale — reduced weekly hours or non-work months for weather-exposed calendars. See weather-and-downtime-allowances for the allowance approach.
Assigning. Default calendar for new activities: Projects → Defaults tab. Set it to the site calendar before you build. Then change the exceptions: curing and procurement to 7-day, design and approvals to office. A quick check before submission: Group and Sort by Calendar, look at what's in each group, and ask whether anything is in the wrong one.
🟥 Where people go wrong
- Everything on the site calendar. Concrete cures on Fridays whether the calendar says so or not; a 7-day cure on a 6-day calendar becomes 8 calendar days. Engineer's reviews run on the Engineer's week, not yours — 14 days of their calendar can be 20 of yours.
- Holidays entered for year one only. The baseline is built in year one, the Eids are in, the National Day is in. Year two has none. Every activity in year two is 10–14 days optimistic.
- Global calendars edited for one project. Someone changes "Standard 6 Day" to add a shutdown. Every project in the database now has the shutdown.
- Midday break in the calendar and in the productivity factor. Counted twice. See productivity-adjustment-factors — hours in the calendar, efficiency in the rate.
- Time Periods left at 8 hours. The activity is 140 hours, meant as 14 days on a 10-hour calendar; the client's reviewer opens it with 8-hour defaults and sees 17.5. Half the review meeting is spent on this.
- Subcontractor calendars imported wholesale. Each XER brings its own "Standard 5 Day" with a different ID. After six imports you have six near-identical calendars and activities scattered across them. Map to your calendars on import.
⚖️ When you're challenged
"Why does the cure show 8 days when the spec says 7?" "Because it's on the 6-day site calendar, so it's skipping Friday. Concrete doesn't. I'll move curing to the 7-day calendar — it'll show 7 and it'll be right."
"Your programme has fewer working days in August than July. Explain." "Midday break. From mid-June to mid-September the site calendar has 8.5 productive hours instead of 10, entered as date exceptions, so anything that lands in that window slows down automatically. It's not padding — it's the labour law, and it's in the basis memorandum with the dates."
"Can we ignore Ramadan? The subcontractor says they'll work full hours." "They may, with a night shift. But their day crews will be on reduced hours by law, and I'd rather plan for what the law requires and report a gain than plan for full hours and report a loss. If they mobilise a night shift I'll add a calendar for it."
📄 Related pages
- Hours per day and duration display — the Time Periods setting and the 17.5-day problem
- Calendar on Relationship Lag — the second calendar setting nobody opens
- Multiple calendars and float — why float goes strange when a path crosses calendars
- Productivity Adjustment Factors — efficiency losses that don't belong in the calendar
- Weather and downtime allowances — rain and sandstorms as allowance, not calendar
- Setting Up a P6 Project — the order of settings before activity one
- Schedule Basis Memorandum — where the calendar set and exception list are recorded
- Cleaning an XER Before Import — mapping subcontractor calendars to yours
✏️ Worked example
Thirty-month office tower, Abu Dhabi, start 1 March. The calendar set and the year-one exceptions:
| Calendar | Type | Exceptions entered |
|---|---|---|
| CAL-SITE-6D-10H | Project | 3 × Eid al-Fitr, 4 × Eid al-Adha, Islamic New Year, 2 × National Day, 1 × Commemoration Day; 15 Jun–15 Sep at 8.5 h; Ramadan month at 8 h — for each of years 1, 2 and 3 (Hijri dates marked approx) |
| CAL-7D-24H | Project | None |
| CAL-OFFICE-5D-8H | Project | Same public holidays; Mon–Fri to match the consultant |
| CAL-VENDOR-CN-6D | Project | Chinese New Year (10 working days), National Day week — years 1 and 2 |
| CAL-TC-7D-20H | Project | None; used for the final 10 weeks only |
Effect on one activity — Façade installation, east elevation, 600 hours (60 days at 10 h), planned to start 1 June:
| Scenario | Working days | Finish |
|---|---|---|
| Site calendar with no summer exceptions | 60 | early August |
| Site calendar with summer exceptions (12 days at 10 h = 120 h, then 480 h at 8.5 h = 56.5 days) | 69 | late August |
Nine working days later, from hours alone, before any heat factor on the rate. Across the six summer-exposed façade activities on that elevation, the accumulated shift was 31 working days on the near-critical path. The tender programme had been built without the exceptions, and that 31 days was most of the gap between tender and baseline that the client wanted explained.
📖 References
- GAO Schedule Assessment Guide (GAO-16-89G), Best Practice 4
- AACE International RP 32R-04, Determining Activity Durations
- PMI, Practice Standard for Scheduling — calendars
- FIDIC 1999 Cl 8.4(c); FIDIC 2017 Cl 8.5(c) (check the edition in your contract); NEC3/NEC4 ECC Cl 60.1(13)
- Current-year midday break decisions of the UAE Ministry of Human Resources and Emiratisation, KSA Ministry of Human Resources and Social Development, Qatar Ministry of Labour (windows change; confirm annually)
- Oracle Primavera P6 Professional User Guide — Calendars (global, project, resource), Exceptions, Admin Preferences → Time Periods, Project Defaults
From the field
Experience from working planners. Unreviewed — read it as experience, not guidance.
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