diff --git a/pytorch_lightning/loggers/csv.py b/pytorch_lightning/loggers/csv.py
index a3c1e46348d140..e9aa13c127cc1b 100644
--- a/pytorch_lightning/loggers/csv.py
+++ b/pytorch_lightning/loggers/csv.py
@@ -34,7 +34,7 @@ class ExperimentWriter(object):
     NAME_HPARAMS_FILE = 'hparams.yaml'
     NAME_METRICS_FILE = 'metrics.csv'
 
-    def __init__(self, log_dir):
+    def __init__(self, log_dir: str) -> None:
         self.hparams = {}
         self.metrics = []
         self.metrics_keys = ["step"]
@@ -49,11 +49,11 @@ def __init__(self, log_dir):
 
         self.metrics_file_path = os.path.join(self.log_dir, self.NAME_METRICS_FILE)
 
-    def log_hparams(self, params):
+    def log_hparams(self, params: Dict[str, Any]) -> None:
         """Record hparams"""
         self.hparams.update(params)
 
-    def log_metrics(self, metrics_dict, step=None):
+    def log_metrics(self, metrics_dict: Dict[str, float], step: Optional[int] = None) -> None:
         """Record metrics"""
         def _handle_value(value):
             if isinstance(value, torch.Tensor):
@@ -71,7 +71,7 @@ def _handle_value(value):
             new_row[k] = _handle_value(v)
         self.metrics.append(new_row)
 
-    def save(self):
+    def save(self) -> None:
         """Save recorded hparams and metrics into files"""
         hparams_file = os.path.join(self.log_dir, self.NAME_HPARAMS_FILE)
         save_hparams_to_yaml(hparams_file, self.hparams)
@@ -135,6 +135,10 @@ def log_dir(self) -> str:
         log_dir = os.path.join(self.root_dir, version)
         return log_dir
 
+    @property
+    def save_dir(self) -> Optional[str]:
+        return self._save_dir
+
     @property
     def experiment(self) -> ExperimentWriter:
         r"""