diff --git a/src/main/java/org/alfresco/repo/download/CreateDownloadArchiveAction.java b/src/main/java/org/alfresco/repo/download/CreateDownloadArchiveAction.java
index 8059f4a690..48f88eeb7e 100644
--- a/src/main/java/org/alfresco/repo/download/CreateDownloadArchiveAction.java
+++ b/src/main/java/org/alfresco/repo/download/CreateDownloadArchiveAction.java
@@ -43,6 +43,7 @@ import org.alfresco.repo.transaction.RetryingTransactionHelper.RetryingTransacti
 import org.alfresco.service.cmr.action.Action;
 import org.alfresco.service.cmr.action.ParameterDefinition;
 import org.alfresco.service.cmr.coci.CheckOutCheckInService;
+import org.alfresco.service.cmr.dictionary.DictionaryService;
 import org.alfresco.service.cmr.download.DownloadRequest;
 import org.alfresco.service.cmr.download.DownloadStatus;
 import org.alfresco.service.cmr.download.DownloadStatus.Status;
@@ -84,6 +85,7 @@ public class CreateDownloadArchiveAction extends ActionExecuterAbstractBase
     private NodeService nodeService;
     private RetryingTransactionHelper transactionHelper;
     private DownloadStatusUpdateService updateService;
+    private DictionaryService dictionaryService;
 
     private long maximumContentSize = -1l;
     
@@ -167,6 +169,11 @@ public class CreateDownloadArchiveAction extends ActionExecuterAbstractBase
         this.updateService = updateService;
     }
 
+    public void setDictionaryService(DictionaryService dictionaryService)
+    {
+        this.dictionaryService = dictionaryService;
+    }
+
     /**
      * Create an archive file containing content from the repository.
      * 
@@ -246,7 +253,7 @@ public class CreateDownloadArchiveAction extends ActionExecuterAbstractBase
     {
         // perform the actual export
         final File tempFile = TempFileProvider.createTempFile(TEMP_FILE_PREFIX, TEMP_FILE_SUFFIX);
-        final ZipDownloadExporter handler = new ZipDownloadExporter(tempFile, checkOutCheckInService, nodeService, transactionHelper, updateService, downloadStorage, actionedUponNodeRef, estimator.getSize(), estimator.getFileCount());
+        final ZipDownloadExporter handler = new ZipDownloadExporter(tempFile, checkOutCheckInService, nodeService, transactionHelper, updateService, downloadStorage, dictionaryService, actionedUponNodeRef, estimator.getSize(), estimator.getFileCount());
         
         try {
             exporterService.exportView(handler, crawlerParameters, null);
diff --git a/src/main/java/org/alfresco/repo/download/ZipDownloadExporter.java b/src/main/java/org/alfresco/repo/download/ZipDownloadExporter.java
index 7aef4c507e..738a6bfbe0 100644
--- a/src/main/java/org/alfresco/repo/download/ZipDownloadExporter.java
+++ b/src/main/java/org/alfresco/repo/download/ZipDownloadExporter.java
@@ -39,6 +39,7 @@ import org.alfresco.model.ContentModel;
 import org.alfresco.repo.transaction.RetryingTransactionHelper;
 import org.alfresco.repo.transaction.RetryingTransactionHelper.RetryingTransactionCallback;
 import org.alfresco.service.cmr.coci.CheckOutCheckInService;
+import org.alfresco.service.cmr.dictionary.DictionaryService;
 import org.alfresco.service.cmr.download.DownloadStatus;
 import org.alfresco.service.cmr.download.DownloadStatus.Status;
 import org.alfresco.service.cmr.repository.ContentData;
@@ -77,6 +78,7 @@ public class ZipDownloadExporter extends BaseExporter
     
     private RetryingTransactionHelper transactionHelper;
     private DownloadStorage downloadStorage;
+    private DictionaryService dictionaryService;
     private DownloadStatusUpdateService updateService;
 
     private Deque<Pair<String, NodeRef>> path = new LinkedList<Pair<String, NodeRef>>();
@@ -93,11 +95,12 @@ public class ZipDownloadExporter extends BaseExporter
      * @param transactionHelper RetryingTransactionHelper
      * @param updateService DownloadStatusUpdateService
      * @param downloadStorage DownloadStorage
+     * @param dictionaryService DictionaryService
      * @param downloadNodeRef NodeRef
      * @param total long
      * @param totalFileCount long
      */
-    public ZipDownloadExporter(File zipFile, CheckOutCheckInService checkOutCheckInService, NodeService nodeService, RetryingTransactionHelper transactionHelper, DownloadStatusUpdateService updateService, DownloadStorage downloadStorage, NodeRef downloadNodeRef, long total, long totalFileCount)
+    public ZipDownloadExporter(File zipFile, CheckOutCheckInService checkOutCheckInService, NodeService nodeService, RetryingTransactionHelper transactionHelper, DownloadStatusUpdateService updateService, DownloadStorage downloadStorage, DictionaryService dictionaryService, NodeRef downloadNodeRef, long total, long totalFileCount)
     {
         super(checkOutCheckInService, nodeService);
         try
@@ -106,6 +109,7 @@ public class ZipDownloadExporter extends BaseExporter
             this.updateService = updateService;
             this.transactionHelper = transactionHelper;
             this.downloadStorage = downloadStorage;
+            this.dictionaryService = dictionaryService;
             
             this.downloadNodeRef = downloadNodeRef;
             this.total = total;
@@ -134,7 +138,7 @@ public class ZipDownloadExporter extends BaseExporter
     {
         this.currentName = (String)nodeService.getProperty(nodeRef, ContentModel.PROP_NAME);
         path.push(new Pair<String, NodeRef>(currentName, nodeRef));
-        if (ContentModel.TYPE_FOLDER.equals(nodeService.getType(nodeRef)))
+        if (dictionaryService.isSubClass(nodeService.getType(nodeRef), ContentModel.TYPE_FOLDER))
         {
             String path = getPath() + PATH_SEPARATOR;
             ZipArchiveEntry archiveEntry = new ZipArchiveEntry(path);
diff --git a/src/main/resources/alfresco/download-services-context.xml b/src/main/resources/alfresco/download-services-context.xml
index e7206022d8..451db5b4a0 100644
--- a/src/main/resources/alfresco/download-services-context.xml
+++ b/src/main/resources/alfresco/download-services-context.xml
@@ -89,18 +89,19 @@
    <bean id="downloadContentServiceHelper" class="org.alfresco.repo.download.LocalContentServiceHelper">
       <property name="contentService" ref="contentService"/>
    </bean>
-   
-   <bean id="createDownloadArchiveAction" class="org.alfresco.repo.download.CreateDownloadArchiveAction" parent="action-executer">
-      <property name="checkOutCheckInSerivce" ref="checkOutCheckInService"/>
-      <property name="contentServiceHelper" ref="downloadContentServiceHelper" />
-     <property name="downloadStorage" ref="downloadStorage" />
-     <property name="exporterService" ref="downloadExporterComponent" />
-     <property name="maximumContentSize" value="${download.maxContentSize}" />
-     <property name="nodeService" ref="nodeService" />
-     <property name="publicAction" value="false"/>
-     <property name="transactionHelper" ref="retryingTransactionHelper"/>
-     <property name="updateService" ref="downloadStatusUpdateService"/>
-   </bean>
+
+    <bean id="createDownloadArchiveAction" class="org.alfresco.repo.download.CreateDownloadArchiveAction" parent="action-executer">
+        <property name="checkOutCheckInSerivce" ref="checkOutCheckInService"/>
+        <property name="contentServiceHelper" ref="downloadContentServiceHelper"/>
+        <property name="downloadStorage" ref="downloadStorage"/>
+        <property name="exporterService" ref="downloadExporterComponent"/>
+        <property name="maximumContentSize" value="${download.maxContentSize}"/>
+        <property name="nodeService" ref="nodeService"/>
+        <property name="publicAction" value="false"/>
+        <property name="transactionHelper" ref="retryingTransactionHelper"/>
+        <property name="updateService" ref="downloadStatusUpdateService"/>
+        <property name="dictionaryService" ref="dictionaryService"/>
+    </bean>
 
     <bean id="downloadExporterComponent" parent="exporterComponent">
         <property name="exportSecondaryNodes" value="true"/>
diff --git a/src/test/java/org/alfresco/repo/download/DownloadServiceIntegrationTest.java b/src/test/java/org/alfresco/repo/download/DownloadServiceIntegrationTest.java
index 29877bff86..3a6db742f6 100644
--- a/src/test/java/org/alfresco/repo/download/DownloadServiceIntegrationTest.java
+++ b/src/test/java/org/alfresco/repo/download/DownloadServiceIntegrationTest.java
@@ -34,6 +34,7 @@ import org.alfresco.repo.security.authentication.AuthenticationUtil;
 import org.alfresco.repo.security.permissions.AccessDeniedException;
 import org.alfresco.repo.transaction.RetryingTransactionHelper;
 import org.alfresco.repo.transaction.RetryingTransactionHelper.RetryingTransactionCallback;
+import org.alfresco.service.cmr.admin.RepoAdminService;
 import org.alfresco.service.cmr.coci.CheckOutCheckInService;
 import org.alfresco.service.cmr.download.DownloadService;
 import org.alfresco.service.cmr.download.DownloadStatus;
@@ -69,8 +70,11 @@ import org.junit.Test;
 import org.junit.experimental.categories.Category;
 import org.junit.rules.RuleChain;
 
+import java.io.ByteArrayInputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.Serializable;
+import java.io.UnsupportedEncodingException;
 import java.util.Date;
 import java.util.List;
 import java.util.Map;
@@ -123,6 +127,7 @@ public class DownloadServiceIntegrationTest
     private static PermissionService         PERMISSION_SERVICE;
     private static RetryingTransactionHelper TRANSACTION_HELPER;
     private static IntegrityChecker          INTEGRITY_CHECKER;
+    private static RepoAdminService          REPO_ADMIN_SERVICE;
     
     // Test Content 
     private NodeRef rootFolder;
@@ -136,6 +141,41 @@ public class DownloadServiceIntegrationTest
     private Set<String> allEntries;
 
     private NodeRef fileToCheckout;
+
+    // MNT-21671 Download as zip does not include custom folders.
+    // Define a custom model that is child of cm:folder
+    private static final String CUSTOM_FOLDER_MODEL_XML =
+        "<model name=\"custom:customModel\" xmlns=\"http://www.alfresco.org/model/dictionary/1.0\">" +
+            "   <description>Custom Model</description>" +
+            "   <author></author>" +
+            "   <version>1.0</version>" +
+
+            "   <imports>" +
+            "      <import uri=\"http://www.alfresco.org/model/dictionary/1.0\" prefix=\"d\"/>" +
+            "      <import uri=\"http://www.alfresco.org/model/content/1.0\" prefix=\"cm\"/>" +
+            "   </imports>" +
+
+            "   <namespaces>" +
+            "      <namespace uri=\"custom.model\" prefix=\"custom\"/>" +
+            "   </namespaces>" +
+
+            "   <types>" +
+            "      <type name=\"custom:folderx\">" +
+            "         <title>Custom FolderX</title>" +
+            "         <parent>cm:folder</parent>" +
+            "         <properties>" +
+            "            <property name=\"custom:invoice\">" +
+            "               <type>d:text</type>" +
+            "            </property>" +
+            "         </properties>" +
+            "         <associations>"  +
+            "         </associations>" +
+            "      </type>" +
+            "   </types>" +
+
+            "   <aspects>" +
+            "   </aspects>" +
+            "</model>";
     
     @BeforeClass public static void init()
     {
@@ -151,6 +191,7 @@ public class DownloadServiceIntegrationTest
         INTEGRITY_CHECKER.setEnabled(true);
         INTEGRITY_CHECKER.setFailOnViolation(true);
         INTEGRITY_CHECKER.setTraceOn(true);
+        REPO_ADMIN_SERVICE = APP_CONTEXT_INIT.getApplicationContext().getBean("RepoAdminService", RepoAdminService.class);
     }
  
     /**
@@ -203,6 +244,24 @@ public class DownloadServiceIntegrationTest
        allEntries.add("rootFolder/level1Folder2/fileToCheckout.txt");
        PERMISSION_SERVICE.setPermission(level1Folder2, TEST_USER.getUsername(), PermissionService.ALL_PERMISSIONS, true);
        PERMISSION_SERVICE.setPermission(fileToCheckout, TEST_USER.getUsername(), PermissionService.ALL_PERMISSIONS, true);
+
+        // MNT-21671 Download as zip does not include custom folders.
+        // deploy custom model
+        final String modelFileName1 = "model-MNT-21671.xml";
+        InputStream modelStream = null;
+        try
+        {
+            modelStream = new ByteArrayInputStream(CUSTOM_FOLDER_MODEL_XML.getBytes("UTF-8"));
+        }
+        catch (UnsupportedEncodingException e)
+        {
+            e.printStackTrace();
+        }
+        REPO_ADMIN_SERVICE.deployModel(modelStream, modelFileName1);
+        final QName customFolderType = QName.createQName("{custom.model}folderx");
+
+        testNodes.createNode(rootFolder, "level1CustomFolder", customFolderType, AuthenticationUtil.getAdminUserName());
+        allEntries.add("rootFolder/level1CustomFolder/");
     }
     
     @Test public void createDownload() throws IOException, InterruptedException