diff --git a/tools/build_apps.py b/tools/build_apps.py
index 1abd2012c5..d95717fd79 100755
--- a/tools/build_apps.py
+++ b/tools/build_apps.py
@@ -6,10 +6,10 @@
 
 import argparse
 import logging
-import shutil
 import sys
 
 from find_build_apps import BuildItem, BuildError, setup_logging, BUILD_SYSTEMS
+from find_build_apps.common import rmdir, SIZE_JSON_FN
 
 
 def main():
@@ -127,9 +127,9 @@ def main():
             if args.size_info:
                 build_info.write_size_info(args.size_info)
             if not build_info.preserve:
-                logging.info("Removing build directory {}".format(build_info.build_dir))
+                logging.info("Removing build directory {}".format(build_info.build_path))
                 # we only remove binaries here, log files are still needed by check_build_warnings.py
-                shutil.rmtree(build_info.build_dir, ignore_errors=True)
+                rmdir(build_info.build_path, exclude_file_pattern=SIZE_JSON_FN)
 
     if failed_builds:
         logging.error("The following build have failed:")
diff --git a/tools/find_build_apps/common.py b/tools/find_build_apps/common.py
index 7b0b1c95ef..51368c5ce8 100644
--- a/tools/find_build_apps/common.py
+++ b/tools/find_build_apps/common.py
@@ -22,6 +22,7 @@ FULL_NAME_PLACEHOLDER = "@f"
 INDEX_PLACEHOLDER = "@i"
 
 IDF_SIZE_PY = os.path.join(os.environ["IDF_PATH"], "tools", "idf_size.py")
+SIZE_JSON_FN = 'size.json'
 
 SDKCONFIG_LINE_REGEX = re.compile(r"^([^=]+)=\"?([^\"\n]*)\"?\n*$")
 
@@ -68,6 +69,22 @@ def find_first_match(pattern, path):
     return None
 
 
+def rmdir(path, exclude_file_pattern=None):
+    if not exclude_file_pattern:
+        shutil.rmtree(path, ignore_errors=True)
+        return
+
+    for root, dirs, files in os.walk(path, topdown=False):
+        for f in files:
+            if not fnmatch.fnmatch(f, exclude_file_pattern):
+                os.remove(os.path.join(root, f))
+        for d in dirs:
+            try:
+                os.rmdir(os.path.join(root, d))
+            except OSError:
+                pass
+
+
 class BuildItem(object):
     """
     Instance of this class represents one build of an application.
@@ -242,7 +259,7 @@ class BuildItem(object):
         if not map_file:
             raise ValueError('.map file not found under "{}"'.format(self.build_path))
 
-        size_json_fp = os.path.join(self.build_path, 'size.json')
+        size_json_fp = os.path.join(self.build_path, SIZE_JSON_FN)
         idf_size_args = [
             sys.executable,
             IDF_SIZE_PY,