diff --git a/lib/permissions/thread-permissions.js b/lib/permissions/thread-permissions.js
--- a/lib/permissions/thread-permissions.js
+++ b/lib/permissions/thread-permissions.js
@@ -176,23 +176,25 @@
   [threadPermissions.ADD_MEMBERS]: true,
 };
 
+const openDescendantKnowOf = OPEN_DESCENDANT + threadPermissions.KNOW_OF;
+const openDescendantVisible = OPEN_DESCENDANT + threadPermissions.VISIBLE;
+const openTopLevelDescendantJoinThread =
+  OPEN_TOP_LEVEL_DESCENDANT + threadPermissions.JOIN_THREAD;
+
+const genesisMemberPermissions = {
+  [threadPermissions.KNOW_OF]: true,
+  [threadPermissions.VISIBLE]: true,
+  [openDescendantKnowOf]: true,
+  [openDescendantVisible]: true,
+  [openTopLevelDescendantJoinThread]: true,
+};
+
 function getRolePermissionBlobsForCommunity(
   threadType: ThreadType,
 ): RolePermissionBlobs {
-  const openDescendantKnowOf = OPEN_DESCENDANT + threadPermissions.KNOW_OF;
-  const openDescendantVisible = OPEN_DESCENDANT + threadPermissions.VISIBLE;
-  const openTopLevelDescendantJoinThread =
-    OPEN_TOP_LEVEL_DESCENDANT + threadPermissions.JOIN_THREAD;
   const openChildJoinThread = OPEN_CHILD + threadPermissions.JOIN_THREAD;
   const openChildAddMembers = OPEN_CHILD + threadPermissions.ADD_MEMBERS;
 
-  const genesisMemberPermissions = {
-    [threadPermissions.KNOW_OF]: true,
-    [threadPermissions.VISIBLE]: true,
-    [openDescendantKnowOf]: true,
-    [openDescendantVisible]: true,
-    [openTopLevelDescendantJoinThread]: true,
-  };
   const baseMemberPermissions = {
     ...genesisMemberPermissions,
     [threadPermissions.REACT_TO_MESSAGE]: true,
@@ -318,8 +320,6 @@
     };
   }
 
-  const openDescendantKnowOf = OPEN_DESCENDANT + threadPermissions.KNOW_OF;
-  const openDescendantVisible = OPEN_DESCENDANT + threadPermissions.VISIBLE;
   const openChildJoinThread = OPEN_CHILD + threadPermissions.JOIN_THREAD;
 
   if (threadType === threadTypes.PRIVATE) {
@@ -362,9 +362,6 @@
     };
   }
 
-  const openTopLevelDescendantJoinThread =
-    OPEN_TOP_LEVEL_DESCENDANT + threadPermissions.JOIN_THREAD;
-
   const subthreadBasePermissions = {
     [threadPermissions.KNOW_OF]: true,
     [threadPermissions.VISIBLE]: true,
@@ -405,6 +402,35 @@
   return getRolePermissionBlobsForCommunity(threadType);
 }
 
+function getUniversalCommunityRootPermissionsBlob(
+  threadType: ThreadType,
+): ThreadRolePermissionsBlob {
+  const openDescendantVoiced = DESCENDANT + OPEN + threadPermissions.VOICED;
+  const openChildJoinThread = CHILD + OPEN + threadPermissions.JOIN_THREAD;
+
+  const baseUniversalCommunityPermissions = {
+    ...genesisMemberPermissions,
+    [threadPermissions.JOIN_THREAD]: true,
+    [threadPermissions.CREATE_SIDEBARS]: true,
+    [threadPermissions.LEAVE_THREAD]: true,
+    [openDescendantVoiced]: true,
+    [openChildJoinThread]: true,
+  };
+
+  if (threadType === threadTypes.GENESIS) {
+    return genesisMemberPermissions;
+  } else if (threadType === threadTypes.COMMUNITY_ANNOUNCEMENT_ROOT) {
+    return baseUniversalCommunityPermissions;
+  } else if (threadType === threadTypes.COMMUNITY_ROOT) {
+    return {
+      ...baseUniversalCommunityPermissions,
+      [threadPermissions.VOICED]: true,
+    };
+  } else {
+    return {};
+  }
+}
+
 export {
   permissionLookup,
   getAllThreadPermissions,
@@ -412,4 +438,5 @@
   makePermissionsForChildrenBlob,
   getRoleForPermissions,
   getRolePermissionBlobs,
+  getUniversalCommunityRootPermissionsBlob,
 };