diff --git a/src/Util/DocrootResolver.php b/src/Util/DocrootResolver.php
index 801814b..4f0477d 100644
--- a/src/Util/DocrootResolver.php
+++ b/src/Util/DocrootResolver.php
@@ -3,37 +3,107 @@
 namespace Thunder\UpdateTester\Util;
 
 use RuntimeException;
+use Symfony\Component\Filesystem\Filesystem;
 
 /**
- * Helper class to resolve docroot folder based on provided site folder.
+ * Helper class to resolve docroot directory based on provided site directory.
  */
 class DocrootResolver {
 
   /**
-   * Get docroot folder for provided site folder.
+   * Common docroot names used for site.
+   *
+   * @var array
+   */
+  protected static $commonDocroot = ['docroot', 'www', 'html'];
+
+  /**
+   * Filtering options for drupal/core package.
+   *
+   * @var array
+   */
+  protected static $drupalCorePackageFilters = [
+    'type:drupal-core',
+    'drupal/core',
+  ];
+
+  /**
+   * Reference file.
+   *
+   * It's used to determine if directory with existence of it, acutally site
+   * docroot directory.
+   *
+   * @var string
+   */
+  protected static $docrootReferenceFile = 'autoload.php';
+
+  /**
+   * Get docroot directory for provided site directory.
    *
    * @param string $siteDirectory
    *   Site directory, can be provided as relative or absolute path.
    *
    * @return string
-   *   Returns absolute path to docroot folder.
+   *   Returns absolute path to docroot directory.
    */
   public static function getDocroot($siteDirectory) {
     $docRoot = realpath($siteDirectory);
 
     if (!is_dir($docRoot)) {
-      throw new RuntimeException('Unable to resolve docroot for provided site folder.');
+      throw new RuntimeException('Provided site directory is not valid.');
+    }
+
+    // Check if provided site directory is used as docroot.
+    if (is_file($docRoot . '/' . static::$docrootReferenceFile)) {
+      return $docRoot;
+    }
+
+    // Resolve docroot using information form composer.json.
+    if (is_file($docRoot . '/composer.json')) {
+      $jsonData = json_decode(file_get_contents($docRoot . '/composer.json'), TRUE);
+
+      if ($jsonData && !empty($jsonData['extra']['installer-paths'])) {
+        foreach ($jsonData['extra']['installer-paths'] as $path => $filters) {
+          if (!empty(array_intersect(static::$drupalCorePackageFilters, $filters))) {
+            $composerBasePath = strstr($path, '/core', TRUE);
+
+            // Skip composer resolving if path '/core' is not found.
+            if (!$composerBasePath) {
+              break;
+            }
+
+            // Absolute paths are not supported.
+            $fileSystem = new Filesystem();
+            if ($fileSystem->isAbsolutePath($composerBasePath)) {
+              break;
+            }
+
+            $composerBasedDocroot = realpath($docRoot . '/' . strstr($path, '/core', TRUE));
+
+            // Validate docroot resolved over composer.json information.
+            if (is_file($composerBasedDocroot . '/' . static::$docrootReferenceFile)) {
+              return $composerBasedDocroot;
+            }
+
+            // Even if docroot is not properly resolved over composer.json
+            // information, it's found by filters provided for core. That's why
+            // there is no point checking other provided install paths.
+            break;
+          }
+        }
+      }
     }
 
-    if (!is_file($docRoot . '/autoload.php')) {
-      $docRoot = realpath($docRoot . '/docroot');
+    // Try to resolve docroot based on common docroot names.
+    foreach (static::$commonDocroot as $commonDocroot) {
+      $commonBasedDocroot = realpath($docRoot . '/' . $commonDocroot);
 
-      if (!is_file($docRoot . '/autoload.php')) {
-        throw new RuntimeException('Unable to resolve docroot for provided site folder.');
+      if (is_file($commonBasedDocroot . '/' . static::$docrootReferenceFile)) {
+        return $commonBasedDocroot;
       }
     }
 
-    return $docRoot;
+    throw new RuntimeException('Unable to resolve docroot for provided site directory.');
   }
 
 }