diff --git a/packages/ui/src/types.ts b/packages/ui/src/types.ts
index 916e7cc6f4..cda2a87483 100644
--- a/packages/ui/src/types.ts
+++ b/packages/ui/src/types.ts
@@ -465,6 +465,7 @@ export interface CalendarItem {
   date: Timestamp
   dueDate: Timestamp
   day: number
+  blockTime: boolean
   access: 'freeBusyReader' | 'reader' | 'writer' | 'owner'
 }
 
diff --git a/plugins/calendar-resources/src/components/DayCalendar.svelte b/plugins/calendar-resources/src/components/DayCalendar.svelte
index cc1c18b40d..e62626c427 100644
--- a/plugins/calendar-resources/src/components/DayCalendar.svelte
+++ b/plugins/calendar-resources/src/components/DayCalendar.svelte
@@ -118,6 +118,7 @@
             allDay: event.allDay,
             date: eventStart,
             dueDate: eventEnd,
+            blockTime: event.blockTime,
             day,
             access: event.access
           })
@@ -136,6 +137,7 @@
           result.push({
             _id: event._id,
             allDay: event.allDay,
+            blockTime: event.blockTime,
             date: eventStart,
             dueDate: eventEnd,
             day: -1,
@@ -343,8 +345,9 @@
     }
   }
 
-  const calcTime = (events: CalendarItem[]): number => {
-    if (events.length === 0) return 0
+  const calcTime = (_events: CalendarItem[]): number => {
+    if (_events.length === 0) return 0
+    const events = _events.filter((ev) => ev.blockTime)
 
     // Extract and sort intervals by start time
     const intervals = events.map((it) => [it.date, it.dueDate]).sort((a, b) => a[0] - b[0])
diff --git a/server-plugins/calendar-resources/src/index.ts b/server-plugins/calendar-resources/src/index.ts
index 1024775879..9fdb02b55f 100644
--- a/server-plugins/calendar-resources/src/index.ts
+++ b/server-plugins/calendar-resources/src/index.ts
@@ -372,6 +372,7 @@ async function onEventCreate (ctx: TxCreateDoc<Event>, control: TriggerControl):
   const { _class, space, attachedTo, attachedToClass, collection, ...attr } = event
   const data = attr as any as Data<Event>
   const calendars = await control.findAll(control.ctx, calendar.class.Calendar, { hidden: false })
+  const events = await control.findAll(control.ctx, calendar.class.Event, { eventId: event.eventId })
   const access = 'reader'
   for (const part of event.participants) {
     const socialIds = await getSocialIds(control, part as Ref<Person>)
@@ -382,6 +383,7 @@ async function onEventCreate (ctx: TxCreateDoc<Event>, control: TriggerControl):
     const user = primarySocialString
     const calendar = getCalendar(calendars, socialStrings)
     if (calendar === undefined) continue
+    if (events.find((p) => p.user === user) !== undefined) continue
     const innerTx = control.txFactory.createTxCreateDoc(
       _class,
       space,