diff --git a/booking.rooms.inc b/booking.rooms.inc
index 2a62386..905d87f 100644
--- a/booking.rooms.inc
+++ b/booking.rooms.inc
@@ -300,6 +300,25 @@ function booking_room_edit_form_validate($form, &$form_state) {
 		3 => 'booking_room_queenbeds',
 	);
 	
+	//watchdog('booking', "<pre>Room Number Form State:\n@info</pre>", array('@info' => print_r( $form_state['values'], true)));
+	
+	//no need to validate if we're just removing the mapping
+	//op won't be defined in the form if it's just receiving the ajax callback, so check that is defined first
+	if (isset($form_state['values']['op']) && $form_state['values']['op'] == 'Remove')
+	{
+		return;
+	}
+	else
+	{
+		if (! _booking_room_capacity_check($values['booking_room_location_id'], $values['booking_room_number'], $values['booking_room_bedtype']))
+		{
+			form_set_error('booking_room_number', 
+				t('Unfortunately there are no beds available of the type specified in the room.')
+			);				
+		}
+	}
+	
+	/*
 	//get the specific room definition from the database
 	$details = db_query("SELECT * FROM {booking_room_definition} WHERE booking_room_location_id = :lid AND booking_room_number = :num",
 		array(':lid' => $values['booking_room_location_id'], ':num' => $values['booking_room_number']))->fetchObject();	
@@ -323,7 +342,48 @@ function booking_room_edit_form_validate($form, &$form_state) {
 			);		
 		}		
 	}
+	*/
+}
 
+/**
+ * Validate there is available capacity for the specified room and bed type
+ * @return TRUE if there is sufficient capacity, otherwise FALSE
+ */
+function _booking_room_capacity_check($room_location_id, $room_number, $room_bedtype) {
+	global $event;
+	
+	$bed_inputs = array(
+		1 => 'booking_room_singlebeds',
+		2 => 'booking_room_doublebeds',
+		3 => 'booking_room_queenbeds',
+	);	
+
+	//make sure the value exists before validating it
+	if (!empty($room_bedtype))
+	{
+		//get the specific room definition from the database
+		$details = db_query("SELECT * FROM {booking_room_definition} WHERE booking_room_location_id = :lid AND booking_room_number = :num",
+			array(':lid' => $room_location_id, ':num' => $room_number))->fetchObject();	
+		
+		//get all person-to-room mappings relating to this room and bed type
+		$mappings = db_query("SELECT count(*) as num FROM {booking_room_mapping} " . 
+			"WHERE booking_eventid = :eid AND booking_roomid = :rid AND booking_room_bedtype = :type",
+			array(':eid' => $event->eid, ':rid' => $details->rid, ':type' => $room_bedtype))->fetchObject();
+
+		$db_field = $bed_inputs[$room_bedtype];
+		$max_beds = $details->$db_field;
+		//check that there is sufficient capacity to allocate another person to this room and bed type
+		if ($mappings->num < $max_beds)
+		{
+			watchdog('booking','Sufficient capacity is available in location !id, room !room, with bed type !type. !count beds remaining of this type',
+				array('!id' => $room_location_id, '!room' => $room_number, '!type' => $room_bedtype, '!count' => $max_beds - $mappings->num));
+				
+			return true;
+		}		
+	}
+	
+	return false;
+	
 }