diff --git a/lib/rtasklib.rb b/lib/rtasklib.rb
index e8f9353..25599bb 100644
--- a/lib/rtasklib.rb
+++ b/lib/rtasklib.rb
@@ -2,15 +2,15 @@
 require_relative "rtasklib/models"
 require_relative "rtasklib/execute"
 require_relative "rtasklib/controller"
+require_relative "rtasklib/helpers"
 require_relative "rtasklib/taskrc"
 
-require "open3"
 require "pathname"
 
 module Rtasklib
 
   class TaskWarrior
-    attr_reader :version, :data_location, :taskrc,
+    attr_reader :version, :data_location, :taskrc, :udas,
                 :override, :override_a, :override_str
 
     include Controller
@@ -31,6 +31,8 @@ def initialize data="#{Dir.home}/.task", opts = {}
       @override      = Taskrc.new(override_h, :hash)
       @override_a    = override.model_to_rc
       @taskrc        = get_rc
+      @udas          = get_udas
+      add_uda_to_model udas
 
       # Check TaskWarrior version, and throw warning if unavailable
       begin
diff --git a/lib/rtasklib/controller.rb b/lib/rtasklib/controller.rb
index a26099e..cd9c852 100644
--- a/lib/rtasklib/controller.rb
+++ b/lib/rtasklib/controller.rb
@@ -40,6 +40,7 @@ def process_ids ids
         ids
       end
     end
+    private :process_ids
 
     def process_tags tags
     end
@@ -96,14 +97,23 @@ def uda_attr? attr
     def arbitrary_attr attr, depth: 1
       attr.to_s.split("_")[depth]
     end
+    private :arbitrary_attr
 
     # Returns all attribute string after given depth
     def deep_attr attr, depth: 2
       attr.to_s.split("_")[depth..-1].join("_")
     end
     private :deep_attr
-    
 
+    def add_uda_to_model uda_hash, model=Rtasklib::Models::TaskModel
+      uda_hash.each do |uda|
+        uda.each do |attr, val|
+          model.attribute attr, String
+        end
+      end
+    end
+    private :add_uda_to_model
+    
     # Retrieve an array of the uda names
     #
     # @return [Array<String>]
@@ -163,6 +173,5 @@ def to_gem_version raw
       Gem::Version.new std_ver
     end
     private :to_gem_version
-
   end
 end
diff --git a/lib/rtasklib/helpers.rb b/lib/rtasklib/helpers.rb
new file mode 100644
index 0000000..e9d0d7a
--- /dev/null
+++ b/lib/rtasklib/helpers.rb
@@ -0,0 +1,33 @@
+
+module Rtasklib
+
+  module Helpers
+    # make this module a stateless, singleton
+    extend self
+
+    # Int needs to precede float because ints are also floats
+    def determine_type value
+      if boolean? value
+        return Axiom::Types::Boolean
+      elsif integer? value
+        return Integer
+      elsif float? value
+        return Float
+      else
+        return String
+      end
+    end
+
+    def integer? value
+      value.to_i.to_s == value
+    end
+
+    def float? value
+      Float(value) rescue false
+    end
+
+    def boolean? value
+      ["on", "off", "yes", "no", "false", "true"].include? value.to_s.downcase
+    end
+  end
+end
diff --git a/lib/rtasklib/models.rb b/lib/rtasklib/models.rb
index 0b778ff..933dbb5 100644
--- a/lib/rtasklib/models.rb
+++ b/lib/rtasklib/models.rb
@@ -1,22 +1,46 @@
 require "virtus"
 require "active_model"
+require 'iso8601'
+require 'date'
 
 module Rtasklib::Models
-  ValidationError = Class.new RuntimeError
 
-  class UUID < Virtus::Attribute
-    def coerce(value)
-      value.to_s
+  # A subclass of the ISO8601::Duration object that use `task calc` to parse
+  # string names like 'weekly', 'biannual', and '3 quarters'
+  #
+  # Modifies the #initialize method, preserving the original string duration
+  class TWDuration < ISO8601::Duration
+    attr_accessor :negative
+    attr_reader   :frozen_value
+
+    def initialize input, base=nil
+      @frozen_value = input.dup.freeze
+      @negative = false
+      parsed = `task calc #{input}`.chomp
+
+      if parsed.include?("-")
+        parsed.gsub!(/\-/, "")
+        negative = true
+      else
+        negative = false
+      end
+
+      super parsed, base
+    end
+  end
+
+  # Custom coercer to change a string input into an TWDuration object
+  class VirtusDuration < Virtus::Attribute
+    def coerce(v)
+      if v.nil? || v.blank? then "" else TWDuration.new(v) end
     end
   end
 
   RcBooleans = Virtus.model do |mod|
     mod.coerce = true
     mod.coercer.config.string.boolean_map = {
-      'no'  => false,
-      'yes' => true,
-      'on'  => true,
-      'off' => false }
+      'yes' => true,  'on'  => true,
+      'no'  => false, 'off' => false }
   end
 
   class TaskrcModel
@@ -61,7 +85,7 @@ class TaskModel
     attribute :wait,          DateTime
 
     # Required only for tasks that are Recurring or have Recurring Parent
-    attribute :recur,         DateTime
+    attribute :recur,         VirtusDuration
 
     # Optional except for tasks with Recurring Parents
     attribute :due,           DateTime
@@ -74,8 +98,6 @@ class TaskModel
     attribute :imask,         String
     attribute :modified,      DateTime
 
-    # TODO: handle arbitrary UDA's
-
     # Refactoring idea, need to understand Virtus internals a bit better
     # [:mask, :imask, :modified, :status, :uuid, :entry].each do |ro_attr|
     #   define_method("set_#{ro_attr.to_s}") do |value|
diff --git a/lib/rtasklib/taskrc.rb b/lib/rtasklib/taskrc.rb
index fe3ed84..4a36e7d 100644
--- a/lib/rtasklib/taskrc.rb
+++ b/lib/rtasklib/taskrc.rb
@@ -123,7 +123,6 @@ def model_to_s
 
     # Dynamically add a Virtus attr, detect Boolean, Integer, and Float types
     # based on the value, otherwise just treat it like a string.
-    # Int needs to precede float because ints are also floats
     # Modifies the config instance variable
     # TODO: May also be able to detect arrays
     #
@@ -132,15 +131,16 @@ def model_to_s
     # @return [undefined]
     # @api private
     def add_model_attr attr, value
-      if boolean? value
-        config.attribute attr.to_sym, Axiom::Types::Boolean
-      elsif integer? value
-        config.attribute attr.to_sym, Integer
-      elsif float? value
-        config.attribute attr.to_sym, Float
-      else
-        config.attribute attr.to_sym, String
-      end
+      config.attribute(attr.to_sym, Helpers.determine_type(value))
+      # if boolean? value
+      #   config.attribute attr.to_sym, Axiom::Types::Boolean
+      # elsif integer? value
+      #   config.attribute attr.to_sym, Integer
+      # elsif float? value
+      #   config.attribute attr.to_sym, Float
+      # else
+      #   config.attribute attr.to_sym, String
+      # end
     end
     private :add_model_attr
 
@@ -194,20 +194,5 @@ def path_exist? path
       end
     end
     private :path_exist?
-
-    def integer? value
-      value.to_i.to_s == value
-    end
-    private :integer?
-
-    def float? value
-      Float(value) rescue false
-    end
-    private :float?
-
-    def boolean? value
-      ["on", "off", "yes", "no", "false", "true"].include? value.to_s.downcase
-    end
-    private :boolean?
   end
 end