diff --git a/src/kernel/building.c b/src/kernel/building.c
index 2877f50fe..48241c398 100644
--- a/src/kernel/building.c
+++ b/src/kernel/building.c
@@ -111,6 +111,10 @@ building_type *bt_get_or_create(const char *name)
         if (btype == NULL) {
             btype = calloc(sizeof(building_type), 1);
             btype->_name = _strdup(name);
+            btype->auraregen = 1.0;
+            btype->maxsize = -1;
+            btype->capacity = -1;
+            btype->maxcapacity = -1;
             bt_register(btype);
         }
         return btype;
diff --git a/src/kernel/building.test.c b/src/kernel/building.test.c
index 6a7d0c17a..72439bad6 100644
--- a/src/kernel/building.test.c
+++ b/src/kernel/building.test.c
@@ -357,10 +357,36 @@ void test_buildingowner_goes_to_empty_unit_after_leave(CuTest * tc)
     test_cleanup();
 }
 
+static void test_btype_defaults(CuTest *tc) {
+    building_type * btype;
+    test_cleanup();
+
+    btype = bt_get_or_create("hodor");
+    CuAssertPtrNotNull(tc, btype);
+    CuAssertPtrEquals(tc, 0, btype->maintenance);
+    CuAssertPtrEquals(tc, 0, btype->construction);
+    CuAssertTrue(tc, !btype->name);
+    CuAssertTrue(tc, !btype->init);
+    CuAssertTrue(tc, !btype->age);
+    CuAssertTrue(tc, !btype->protection);
+    CuAssertTrue(tc, !btype->taxes);
+    CuAssertStrEquals(tc, "hodor", btype->_name);
+    CuAssertDblEquals(tc, 1.0, btype->auraregen, 0.0);
+    CuAssertIntEquals(tc, -1, btype->maxsize);
+    CuAssertIntEquals(tc, -1, btype->capacity);
+    CuAssertIntEquals(tc, -1, btype->maxcapacity);
+    CuAssertIntEquals(tc, 0, btype->magres);
+    CuAssertIntEquals(tc, 0, btype->magresbonus);
+    CuAssertIntEquals(tc, 0, btype->fumblebonus);
+    CuAssertIntEquals(tc, 0, btype->flags);
+    test_cleanup();
+}
+
 CuSuite *get_building_suite(void)
 {
     CuSuite *suite = CuSuiteNew();
     SUITE_ADD_TEST(suite, test_register_building);
+    SUITE_ADD_TEST(suite, test_btype_defaults);
     SUITE_ADD_TEST(suite, test_building_set_owner);
     SUITE_ADD_TEST(suite, test_buildingowner_resets_when_empty);
     SUITE_ADD_TEST(suite, test_buildingowner_goes_to_next_when_empty);
diff --git a/src/kernel/jsonconf.test.c b/src/kernel/jsonconf.test.c
index 3bba66a88..177340fe0 100644
--- a/src/kernel/jsonconf.test.c
+++ b/src/kernel/jsonconf.test.c
@@ -296,6 +296,30 @@ static void test_buildings(CuTest * tc)
     test_cleanup();
 }
 
+static const char * building_defaults_data = "{\"buildings\": { "
+"\"house\" : { }"
+"}}";
+
+static void test_buildings_default(CuTest * tc)
+{
+    cJSON *json = cJSON_Parse(building_defaults_data);
+    const building_type *bt;
+    building_type clone;
+
+    test_cleanup();
+
+    bt = bt_get_or_create("house");
+    clone = *bt;
+
+    CuAssertIntEquals(tc, 0, memcmp(bt, &clone, sizeof(building_type)));
+    CuAssertPtrNotNull(tc, json);
+    json_config(json);
+
+    CuAssertPtrEquals(tc, (void *)bt, (void *)bt_find("house"));
+    CuAssertIntEquals(tc, 0, memcmp(bt, &clone, sizeof(building_type)));
+    test_cleanup();
+}
+
 static void test_configs(CuTest * tc)
 {
     const char * data = "{\"include\": [ \"test.json\" ] }";
@@ -448,6 +472,7 @@ CuSuite *get_jsonconf_suite(void)
     SUITE_ADD_TEST(suite, test_items);
     SUITE_ADD_TEST(suite, test_ships);
     SUITE_ADD_TEST(suite, test_buildings);
+    SUITE_ADD_TEST(suite, test_buildings_default);
     SUITE_ADD_TEST(suite, test_configs);
     SUITE_ADD_TEST(suite, test_castles);
     SUITE_ADD_TEST(suite, test_terrains);
diff --git a/src/kernel/xmlreader.c b/src/kernel/xmlreader.c
index 055615d02..5d4c8dc99 100644
--- a/src/kernel/xmlreader.c
+++ b/src/kernel/xmlreader.c
@@ -244,14 +244,14 @@ static int parse_buildings(xmlDocPtr doc)
             btype = bt_get_or_create((const char *)propValue);
             xmlFree(propValue);
 
-            btype->capacity = xml_ivalue(node, "capacity", -1);
-            btype->maxcapacity = xml_ivalue(node, "maxcapacity", -1);
-            btype->maxsize = xml_ivalue(node, "maxsize", -1);
+            btype->capacity = xml_ivalue(node, "capacity", btype->capacity);
+            btype->maxcapacity = xml_ivalue(node, "maxcapacity", btype->maxcapacity);
+            btype->maxsize = xml_ivalue(node, "maxsize", btype->maxsize);
 
-            btype->magres = xml_ivalue(node, "magres", 0);
-            btype->magresbonus = xml_ivalue(node, "magresbonus", 0);
-            btype->fumblebonus = xml_ivalue(node, "fumblebonus", 0);
-            btype->auraregen = xml_fvalue(node, "auraregen", 1.0);
+            btype->magres = xml_ivalue(node, "magres", btype->magres);
+            btype->magresbonus = xml_ivalue(node, "magresbonus", btype->magresbonus);
+            btype->fumblebonus = xml_ivalue(node, "fumblebonus", btype->fumblebonus);
+            btype->auraregen = xml_fvalue(node, "auraregen", btype->auraregen);
 
             if (xml_bvalue(node, "nodestroy", false))
                 btype->flags |= BTF_INDESTRUCTIBLE;
@@ -305,9 +305,6 @@ static int parse_buildings(xmlDocPtr doc)
                 else if (strcmp((const char *)propValue, "taxes") == 0) {
                     btype->taxes = (double(*)(const struct building *, int))fun;
                 }
-                else if (strcmp((const char *)propValue, "age") == 0) {
-                    btype->age = (void(*)(struct building *))fun;
-                }
                 else {
                     log_error("unknown function type '%s' for building %s\n", (const char *)propValue, btype->_name);
                 }