diff --git a/lib/osut/utils.rb b/lib/osut/utils.rb
index c9148b9..17eea0f 100644
--- a/lib/osut/utils.rb
+++ b/lib/osut/utils.rb
@@ -1028,7 +1028,7 @@ def rsi(lc = nil, film = 0.0, t = 0.0)
   end
 
   ##
-  # Identify a layered construction's (opaque) insulating layer. The method
+  # Identifies a layered construction's (opaque) insulating layer. The method
   # returns a 3-keyed hash :index, the insulating layer index [0, n layers)
   # within the layered construction; :type, either :standard or :massless; and
   # :r, material thermal resistance in m2•K/W.
@@ -1082,6 +1082,36 @@ def insulatingLayer(lc = nil)
     res
   end
 
+  ##
+  # Validates whether opaque surface can be considered as a curtain wall (or
+  # similar technology) spandrel, regardless of construction layers, by looking
+  # up AdditionalProperties or its identifier.
+  #
+  # @param s [OpenStudio::Model::Surface] an opaque surface
+  #
+  # @return [Bool] whether surface can be considered 'spandrel'
+  # @return [false] if invalid input (see logs)
+  def spandrel?(s = nil)
+    mth = "OSut::#{__callee__}"
+    cl  = OpenStudio::Model::Surface
+    return invalid("surface", mth, 1, DBG, false) unless s.respond_to?(NS)
+
+    id = s.nameString
+    m1  = "#{id}:spandrel"
+    m2  = "#{id}:spandrel:boolean"
+
+    if s.additionalProperties.hasFeature("spandrel")
+      val = s.additionalProperties.getFeatureAsBoolean("spandrel")
+      return invalid(m1, mth, 1, ERR, false) if val.empty?
+
+      val = val.get
+      return invalid(m2, mth, 1, ERR, false) unless [true, false].include?(val)
+      return val
+    end
+
+    id.downcase.include?("spandrel")
+  end
+
   # ---- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---- #
   # ---- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---- #
   # This next set of utilities (~850 lines) help distinguish spaces that are
@@ -1546,8 +1576,8 @@ def maxHeatScheduledSetpoint(zone = nil)
   #
   # @param model [OpenStudio::Model::Model] a model
   #
-  # @return [Bool] wether model holds valid heating temperature setpoints
-  # @return [false] false if invalid input (see logs)
+  # @return [Bool] whether model holds valid heating temperature setpoints
+  # @return [false] if invalid input (see logs)
   def heatingTemperatureSetpoints?(model = nil)
     mth = "OSut::#{__callee__}"
     cl  = OpenStudio::Model::Model
@@ -1784,7 +1814,7 @@ def vestibule?(space = nil)
 
     id  = space.nameString
     m1  = "#{id}:vestibule"
-    m1  = "#{id}:vestibule boolean"
+    m2  = "#{id}:vestibule:boolean"
 
     if space.additionalProperties.hasFeature("vestibule")
       val = space.additionalProperties.getFeatureAsBoolean("vestibule")
@@ -2814,7 +2844,7 @@ def height(pts = nil)
   # @param flat [Bool] whether points are to be pre-flattened (Z=0)
   #
   # @return [Bool] whether 1st polygon fits within the 2nd polygon
-  # @return [false] false if invalid input (see logs)
+  # @return [false] if invalid input (see logs)
   def fits?(p1 = nil, p2 = nil, flat = true)
     mth  = "OSut::#{__callee__}"
     p1   = poly(p1, false, true, false)
diff --git a/spec/osut_tests_spec.rb b/spec/osut_tests_spec.rb
index c6a6382..58149a5 100644
--- a/spec/osut_tests_spec.rb
+++ b/spec/osut_tests_spec.rb
@@ -678,6 +678,57 @@
     expect(mod1.logs.first[:message]).to eq(m1)
   end
 
+  it "checks for spandrels" do
+    translator = OpenStudio::OSVersion::VersionTranslator.new
+    expect(mod1.clean!).to eq(DBG)
+
+    file  = File.join(__dir__, "files/osms/in/seb.osm")
+    path  = OpenStudio::Path.new(file)
+    model = translator.loadModel(path)
+    expect(model).to_not be_empty
+    model = model.get
+
+    office_walls = []
+    # Smalloffice 1 Wall 1
+    # Smalloffice 1 Wall 2
+    # Smalloffice 1 Wall 6
+    plenum_walls = []
+    # Level0 Small office 1 Ceiling Plenum AbvClgPlnmWall 6
+    # Level0 Small office 1 Ceiling Plenum AbvClgPlnmWall 2
+    # Level0 Small office 1 Ceiling Plenum AbvClgPlnmWall 1
+
+    model.getSurfaces.each do |s|
+      next unless s.outsideBoundaryCondition.downcase == "outdoors"
+      next unless s.surfaceType.downcase == "wall"
+
+      expect(mod1.spandrel?(s)).to be false
+
+      if s.nameString.downcase.include?("smalloffice 1")
+        office_walls << s
+      elsif s.nameString.downcase.include?("small office 1 ceiling plenum")
+        plenum_walls << s
+      end
+    end
+
+    expect(office_walls.size).to eq(3)
+    expect(plenum_walls.size).to eq(3)
+    expect(mod1.status).to be_zero
+
+    # Tag Small Office walls (& plenum walls) in SEB as 'spandrels'.
+    tag = "spandrel"
+
+    (office_walls + plenum_walls).each do |wall|
+      expect(wall.additionalProperties.setFeature(tag, true)).to be true
+      expect(wall.additionalProperties.hasFeature(tag)).to be true
+      prop = wall.additionalProperties.getFeatureAsBoolean(tag)
+      expect(prop).to_not be_empty
+      expect(prop.get).to be true
+      expect(mod1.spandrel?(wall)).to be true
+    end
+
+    expect(mod1.status).to be_zero
+  end
+
   it "checks scheduleRulesetMinMax (from within class instances)" do
     translator = OpenStudio::OSVersion::VersionTranslator.new
     expect(cls1.level).to eq(DBG)