diff --git a/pyproject.toml b/pyproject.toml
index fea21af..411737e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "osut"
-version = "0.9.0"
+version = "0.9.1"
 description = "OpenStudio SDK utilities for Python"
 readme = "README.md"
 requires-python = ">=3.2"
diff --git a/src/osut/osut.py b/src/osut/osut.py
index 7f2f7bf..8b565ae 100644
--- a/src/osut/osut.py
+++ b/src/osut/osut.py
@@ -533,7 +533,7 @@ def rsi(lc=None, film=0.0, t=0.0) -> float:
         if m.to_StandardOpaqueMaterial():
             rsi += m.to_StandardOpaqueMaterial().get().thermalResistance()
         elif m.to_MasslessOpaqueMaterial():
-            rsi += m.to_MasslessOpaqueMaterial()
+            rsi += m.to_MasslessOpaqueMaterial().get().thermalResistance()
         elif m.to_RoofVegetation():
             rsi += m.to_RoofVegetation().get().thermalResistance()
         elif m.to_AirGap():
@@ -563,7 +563,7 @@ def insulatingLayer(lc=None) -> dict:
     mth = "osut.insulatingLayer"
     cl  = openstudio.model.LayeredConstruction
     res = dict(index=None, type=None, r=0.0)
-    i   = 0  # iterator
+    i   = 0 # iterator
 
     if not isinstance(lc, cl):
         return oslg.mismatch("lc", lc, cl, mth, CN.DBG, res)
@@ -572,11 +572,11 @@ def insulatingLayer(lc=None) -> dict:
         if l.to_MasslessOpaqueMaterial():
             l = l.to_MasslessOpaqueMaterial().get()
 
-            if l.thermalResistance() < 0.001 or l.thermalResistance() < res["r"]:
+            if l.thermalResistance() < CN.RMIN or l.thermalResistance() < res["r"]:
                 i += 1
                 continue
             else:
-                res["r"    ] = m.thermalResistance()
+                res["r"    ] = l.thermalResistance()
                 res["index"] = i
                 res["type" ] = "massless"
 
@@ -585,7 +585,7 @@ def insulatingLayer(lc=None) -> dict:
             k = l.thermalConductivity()
             d = l.thickness()
 
-            if (d < 0.003) or (k > 3.0) or (d / k < res["r"]):
+            if (d < CN.DMIN) or (k > CN.KMAX) or (d / k < res["r"]):
                 i += 1
                 continue
             else: