diff --git a/PyTeX/build/build/__init__.py b/PyTeX/build/build/__init__.py
index b084ded..259bf96 100644
--- a/PyTeX/build/build/__init__.py
+++ b/PyTeX/build/build/__init__.py
@@ -1,2 +1,2 @@
-from .build_dir_spec import BuildDirSpecification
+from .build_dir_spec import BuildDirConfig
 from .builder import PyTeXBuilder
diff --git a/PyTeX/build/build/build_dir_spec.py b/PyTeX/build/build/build_dir_spec.py
index 9846557..a42f1b1 100644
--- a/PyTeX/build/build/build_dir_spec.py
+++ b/PyTeX/build/build/build_dir_spec.py
@@ -1,8 +1,10 @@
 from pathlib import Path, PurePath
-from typing import Optional
+from typing import Optional, Dict
+from .constants import *
+from ...format.config import Config, recursive_merge_dictionaries, clean_dict
 
 
-class BuildDirSpecification:
+class BuildDirConfig(Config):
     def __init__(
             self,
             source_root: Optional[Path] = None,
@@ -17,6 +19,24 @@ class BuildDirSpecification:
         self._tex_source_root: Optional[Path] = tex_root
         self._wrapper_dir: Optional[PurePath] = wrapper_dir
 
+    def set_from_json(self, content: Dict):
+        content = self._fill_keys(content)
+
+        self._tex_source_root = content[YAML_TEX_SOURCE_ROOT]
+        self._pytex_source_root = content[YAML_PYTEX_SOURCE_ROOT]
+        self._build_root = content[YAML_BUILD_ROOT]
+        self._doc_root = content[YAML_DOC_ROOT]
+        self._wrapper_dir = content[YAML_WRAPPER_DIR]
+
+    def to_json(self) -> Dict:
+        return {
+            YAML_WRAPPER_DIR: self._wrapper_dir,
+            YAML_BUILD_ROOT: self._build_root,
+            YAML_DOC_ROOT: self._doc_root,
+            YAML_TEX_SOURCE_ROOT: self._tex_source_root,
+            YAML_PYTEX_SOURCE_ROOT: self._pytex_source_root
+        }
+
     @property
     def build_root(self) -> Path:
         if self._build_root is None:
diff --git a/PyTeX/build/build/builder.py b/PyTeX/build/build/builder.py
index 2e7a62b..4e01bfc 100644
--- a/PyTeX/build/build/builder.py
+++ b/PyTeX/build/build/builder.py
@@ -1,7 +1,7 @@
 from typing import Optional
 from pathlib import Path
 
-from PyTeX.build.build import BuildDirSpecification
+from PyTeX.build.build import BuildDirConfig
 from PyTeX.build.enums import PyTeXRootDirType
 from ...logger import logger
 from .pytex_config import PyTeXConfig
@@ -10,7 +10,7 @@ from .pytex_config import PyTeXConfig
 class PyTeXBuilder:
     def __init__(
             self,
-            build_dir_spec: BuildDirSpecification
+            build_dir_spec: BuildDirConfig
     ):
 
         self._build_target_type: Optional[PyTeXRootDirType] = None
diff --git a/PyTeX/build/build/constants.py b/PyTeX/build/build/constants.py
new file mode 100644
index 0000000..a6c3b59
--- /dev/null
+++ b/PyTeX/build/build/constants.py
@@ -0,0 +1,10 @@
+YAML_BUILD_ROOT = 'build'
+YAML_PYTEX_SOURCE_ROOT = 'source'
+YAML_TEX_SOURCE_ROOT = 'tex'
+YAML_DOC_ROOT = 'doc'
+YAML_RECURSIVE = 'recursive'
+YAML_CLEAN_OLD_FILES = 'clean'
+YAML_OVERWRITE_FILES = 'overwrite'
+YAML_ALLOW_DIRTY_BUILD = 'dirty'
+YAML_FORCE_MODE = 'force'
+YAML_WRAPPER_DIR = 'wrapper'
diff --git a/PyTeX/build/build/pytex_config.py b/PyTeX/build/build/pytex_config.py
index ef4cbb5..7980949 100644
--- a/PyTeX/build/build/pytex_config.py
+++ b/PyTeX/build/build/pytex_config.py
@@ -1,15 +1,15 @@
 from typing import Optional
 
-from PyTeX.build.build import BuildDirSpecification
+from PyTeX.build.build import BuildDirConfig
 from PyTeX.format.formatting_config import FormattingConfig
 
 
 class PyTeXConfig:
     def __init__(
             self,
-            build_dir_spec: Optional[BuildDirSpecification] = None
+            build_dir_spec: Optional[BuildDirConfig] = None
     ):
-        self._build_dir_specification: Optional[BuildDirSpecification] = build_dir_spec
+        self._build_dir_specification: Optional[BuildDirConfig] = build_dir_spec
 
         self._default_formatting_config: Optional[FormattingConfig] = None
 
@@ -21,7 +21,7 @@ class PyTeXConfig:
     @property
     def build_dir_specification(self):
         if self._build_dir_specification is None:
-            return BuildDirSpecification()
+            return BuildDirConfig()
         else:
             return self._build_dir_specification
 
diff --git a/PyTeX/format/config.py b/PyTeX/format/config.py
index e1029de..b94ea3f 100644
--- a/PyTeX/format/config.py
+++ b/PyTeX/format/config.py
@@ -76,6 +76,13 @@ class Config:
             else:
                 pass  # TODO
 
+    @classmethod
+    def _fill_keys(cls, dictionary: Dict):
+        return recursive_merge_dictionaries(
+            cls().to_json(),
+            dictionary
+        )
+
 
 def recursive_merge_dictionaries(dict1: Dict, dict2: Dict) -> Dict:
 
diff --git a/PyTeX/format/formatting_config.py b/PyTeX/format/formatting_config.py
index 664d5f8..8e5e547 100644
--- a/PyTeX/format/formatting_config.py
+++ b/PyTeX/format/formatting_config.py
@@ -59,10 +59,7 @@ class FormattingConfig(Config):
         self._tex_flavour: Optional[TeXFlavour] = None
 
     def set_from_json(self, content: Dict):
-        content = recursive_merge_dictionaries(
-            FormattingConfig().to_json(),
-            content
-        )
+        content = self._fill_keys(content)
 
         info = content[YAML_INFO]
         self._author = info[YAML_AUTHOR]
diff --git a/main.py b/main.py
index 162366d..d64ed6b 100644
--- a/main.py
+++ b/main.py
@@ -1,13 +1,13 @@
 from pathlib import Path
 from PyTeX.build.build import PyTeXBuilder
-from PyTeX.build.build.build_dir_spec import BuildDirSpecification
+from PyTeX.build.build.build_dir_spec import BuildDirConfig
 from PyTeX.build.enums import *
 from PyTeX.build.paths import RelativePath
 
 from PyTeX.format.formatting_config import FormattingConfig
 from PyTeX.format.generic_text import GenericText
 
-spec = BuildDirSpecification(
+spec = BuildDirConfig(
     source_root=Path('src'),
     tex_root=Path('build/source'),
     build_root=Path('build'),