diff --git a/include/openPMD/Mesh.hpp b/include/openPMD/Mesh.hpp
index 38db4df2e9..1c255e3910 100644
--- a/include/openPMD/Mesh.hpp
+++ b/include/openPMD/Mesh.hpp
@@ -231,7 +231,7 @@ class Mesh : public BaseRecord<MeshRecordComponent>
 
     void
     flush_impl(std::string const &, internal::FlushParams const &) override;
-    void read() override;
+    void read();
 }; // Mesh
 
 template <typename T>
diff --git a/include/openPMD/Record.hpp b/include/openPMD/Record.hpp
index 4f7ee51c28..c875389db5 100644
--- a/include/openPMD/Record.hpp
+++ b/include/openPMD/Record.hpp
@@ -52,7 +52,7 @@ class Record : public BaseRecord<RecordComponent>
 
     void
     flush_impl(std::string const &, internal::FlushParams const &) override;
-    void read() override;
+    void read();
 }; // Record
 
 template <typename T>
diff --git a/include/openPMD/RecordComponent.hpp b/include/openPMD/RecordComponent.hpp
index 40e4723db1..597e47c4cc 100644
--- a/include/openPMD/RecordComponent.hpp
+++ b/include/openPMD/RecordComponent.hpp
@@ -434,7 +434,7 @@ class RecordComponent : public BaseRecordComponent
 private:
     void flush(
         std::string const &, internal::FlushParams const &, bool set_defaults);
-    virtual void read();
+    void read(bool read_defaults);
 
     /**
      * Internal method to be called by all methods that create an empty dataset.
@@ -486,7 +486,7 @@ OPENPMD_protected
         BaseRecordComponent::setData(m_recordComponentData);
     }
 
-    void readBase();
+    void readBase(bool read_defaults);
 }; // RecordComponent
 
 } // namespace openPMD
diff --git a/include/openPMD/backend/MeshRecordComponent.hpp b/include/openPMD/backend/MeshRecordComponent.hpp
index 3d10cedacd..d05163d754 100644
--- a/include/openPMD/backend/MeshRecordComponent.hpp
+++ b/include/openPMD/backend/MeshRecordComponent.hpp
@@ -46,7 +46,7 @@ class MeshRecordComponent : public RecordComponent
 private:
     MeshRecordComponent();
     MeshRecordComponent(NoInit);
-    void read() override;
+    void read();
     void flush(std::string const &, internal::FlushParams const &);
 
 public:
diff --git a/src/CustomHierarchy.cpp b/src/CustomHierarchy.cpp
index 86970e5437..0708c91e4c 100644
--- a/src/CustomHierarchy.cpp
+++ b/src/CustomHierarchy.cpp
@@ -487,7 +487,7 @@ void CustomHierarchy::read(
                 rc.written() = false;
                 rc.resetDataset(Dataset(*dOpen.dtype, *dOpen.extent));
                 rc.written() = true;
-                rc.read();
+                rc.read(/* read_defaults = */ false);
             }
             catch (error::ReadError const &err)
             {
@@ -533,7 +533,7 @@ void CustomHierarchy::read(
             pOpen.path = path;
             IOHandler()->enqueue(IOTask(&rc, pOpen));
             rc.get().m_isConstant = true;
-            rc.read();
+            rc.read(/* read_defaults = */ false);
         }
         catch (error::ReadError const &err)
         {
diff --git a/src/Record.cpp b/src/Record.cpp
index 568d66be46..07c4f1fa8a 100644
--- a/src/Record.cpp
+++ b/src/Record.cpp
@@ -109,7 +109,7 @@ void Record::read()
         /* using operator[] will incorrectly update parent */
         try
         {
-            T_RecordComponent::read();
+            T_RecordComponent::read(/* read_defaults = */ true);
         }
         catch (error::ReadError const &err)
         {
@@ -133,7 +133,7 @@ void Record::read()
             rc.get().m_isConstant = true;
             try
             {
-                rc.read();
+                rc.read(/* read_defaults = */ true);
             }
             catch (error::ReadError const &err)
             {
@@ -160,7 +160,7 @@ void Record::read()
             rc.written() = true;
             try
             {
-                rc.read();
+                rc.read(/* read_defaults = */ true);
             }
             catch (error::ReadError const &err)
             {
diff --git a/src/RecordComponent.cpp b/src/RecordComponent.cpp
index 0293fea89d..87ccf6c3ad 100644
--- a/src/RecordComponent.cpp
+++ b/src/RecordComponent.cpp
@@ -342,9 +342,9 @@ void RecordComponent::flush(
     }
 }
 
-void RecordComponent::read()
+void RecordComponent::read(bool read_defaults)
 {
-    readBase();
+    readBase(read_defaults);
 }
 
 namespace
@@ -369,7 +369,7 @@ namespace
     };
 } // namespace
 
-void RecordComponent::readBase()
+void RecordComponent::readBase(bool read_defaults)
 {
     using DT = Datatype;
     // auto & rc = get();
@@ -415,20 +415,23 @@ void RecordComponent::readBase()
         written() = true;
     }
 
-    aRead.name = "unitSI";
-    IOHandler()->enqueue(IOTask(this, aRead));
-    IOHandler()->flush(internal::defaultFlushParams);
-    if (auto val = Attribute(*aRead.resource).getOptional<double>();
-        val.has_value())
-        setUnitSI(val.value());
-    else
-        throw error::ReadError(
-            error::AffectedObject::Attribute,
-            error::Reason::UnexpectedContent,
-            {},
-            "Unexpected Attribute datatype for 'unitSI' (expected double, "
-            "found " +
-                datatypeToString(Attribute(*aRead.resource).dtype) + ")");
+    if (read_defaults)
+    {
+        aRead.name = "unitSI";
+        IOHandler()->enqueue(IOTask(this, aRead));
+        IOHandler()->flush(internal::defaultFlushParams);
+        if (auto val = Attribute(*aRead.resource).getOptional<double>();
+            val.has_value())
+            setUnitSI(val.value());
+        else
+            throw error::ReadError(
+                error::AffectedObject::Attribute,
+                error::Reason::UnexpectedContent,
+                {},
+                "Unexpected Attribute datatype for 'unitSI' (expected double, "
+                "found " +
+                    datatypeToString(Attribute(*aRead.resource).dtype) + ")");
+    }
 
     readAttributes(ReadMode::FullyReread);
 }
diff --git a/src/backend/MeshRecordComponent.cpp b/src/backend/MeshRecordComponent.cpp
index 8bf617ef3e..10bee1cf45 100644
--- a/src/backend/MeshRecordComponent.cpp
+++ b/src/backend/MeshRecordComponent.cpp
@@ -64,7 +64,7 @@ void MeshRecordComponent::read()
             "of any floating point type, found " +
                 datatypeToString(Attribute(*aRead.resource).dtype) + ")");
 
-    readBase();
+    readBase(/* read_defaults = */ true);
 }
 
 void MeshRecordComponent::flush(