diff --git a/src/Umbraco.Configuration/Legacy/ModelsBuilderConfig.cs b/src/Umbraco.Configuration/Legacy/ModelsBuilderConfig.cs
index f6395b23b4..164b15c728 100644
--- a/src/Umbraco.Configuration/Legacy/ModelsBuilderConfig.cs
+++ b/src/Umbraco.Configuration/Legacy/ModelsBuilderConfig.cs
@@ -32,7 +32,7 @@ namespace Umbraco.Configuration.Legacy
         {
             // giant kill switch, default: false
             // must be explicitely set to true for anything else to happen
-            Enable = ConfigurationManager.AppSettings[Prefix + "Enable"] == "true";
+            Enable = true;
 
             // ensure defaults are initialized for tests
             ModelsNamespace = Constants.ModelsBuilder.DefaultModelsNamespace;
diff --git a/src/Umbraco.Configuration/Models/ModelsBuilderConfig.cs b/src/Umbraco.Configuration/Models/ModelsBuilderConfig.cs
index d111dbba70..f797cc4383 100644
--- a/src/Umbraco.Configuration/Models/ModelsBuilderConfig.cs
+++ b/src/Umbraco.Configuration/Models/ModelsBuilderConfig.cs
@@ -29,7 +29,7 @@ namespace Umbraco.Configuration.Models
         ///     <para>If this is false then absolutely nothing happens.</para>
         ///     <para>Default value is <c>false</c> which means that unless we have this setting, nothing happens.</para>
         /// </remarks>
-        public bool Enable => _configuration.GetValue(Prefix+"Enable", false);
+        public bool Enable => _configuration.GetValue(Prefix+"Enable", true);
 
         /// <summary>
         ///     Gets the models mode.
diff --git a/src/Umbraco.Core/Composing/DefaultUmbracoAssemblyProvider.cs b/src/Umbraco.Core/Composing/DefaultUmbracoAssemblyProvider.cs
index c5d87abf91..3e0ea9c971 100644
--- a/src/Umbraco.Core/Composing/DefaultUmbracoAssemblyProvider.cs
+++ b/src/Umbraco.Core/Composing/DefaultUmbracoAssemblyProvider.cs
@@ -19,7 +19,7 @@ namespace Umbraco.Core.Composing
                 "Umbraco.Core",
                 "Umbraco.Infrastructure",
                 "Umbraco.PublishedCache.NuCache",
-              //  "Umbraco.ModelsBuilder.Embedded", TODO reintroduce when ModelsBuilder is migrated
+                "Umbraco.ModelsBuilder.Embedded",
                 "Umbraco.Examine.Lucene",
                 "Umbraco.Web.Common",
                 "Umbraco.Web.BackOffice",
diff --git a/src/Umbraco.Core/Configuration/ModelsBuilderConfigExtensions.cs b/src/Umbraco.Core/Configuration/ModelsBuilderConfigExtensions.cs
index 3e3b116395..07b344cec3 100644
--- a/src/Umbraco.Core/Configuration/ModelsBuilderConfigExtensions.cs
+++ b/src/Umbraco.Core/Configuration/ModelsBuilderConfigExtensions.cs
@@ -1,5 +1,6 @@
 using System.Configuration;
 using System.IO;
+using Umbraco.Core.Hosting;
 using Umbraco.Core.IO;
 
 namespace Umbraco.Core.Configuration
@@ -8,13 +9,13 @@ namespace Umbraco.Core.Configuration
     {
         private static string _modelsDirectoryAbsolute = null;
 
-        public static string ModelsDirectoryAbsolute(this IModelsBuilderConfig modelsBuilderConfig, IIOHelper ioHelper)
+        public static string ModelsDirectoryAbsolute(this IModelsBuilderConfig modelsBuilderConfig, IHostingEnvironment hostingEnvironment)
         {
 
             if (_modelsDirectoryAbsolute is null)
             {
                 var modelsDirectory = modelsBuilderConfig.ModelsDirectory;
-                var root = ioHelper.MapPath("~/");
+                var root = hostingEnvironment.MapPathContentRoot("~/");
 
                 _modelsDirectoryAbsolute = GetModelsDirectory(root, modelsDirectory,
                     modelsBuilderConfig.AcceptUnsafeModelsDirectory);
diff --git a/src/Umbraco.Core/PublishedModelFactoryExtensions.cs b/src/Umbraco.Core/PublishedModelFactoryExtensions.cs
index a877d6a7f5..dcfa076cae 100644
--- a/src/Umbraco.Core/PublishedModelFactoryExtensions.cs
+++ b/src/Umbraco.Core/PublishedModelFactoryExtensions.cs
@@ -64,7 +64,7 @@ namespace Umbraco.Core
             {
                 lock (liveFactory.SyncRoot)
                 {
-                    liveFactory.Reset();
+                    liveFactory.Refresh(); // TODO: Reset to Reset
 
                     action();
                 }
diff --git a/src/Umbraco.ModelsBuilder.Embedded/Building/Builder.cs b/src/Umbraco.ModelsBuilder.Embedded/Building/Builder.cs
index 0e75a3839a..d49b6eb0a6 100644
--- a/src/Umbraco.ModelsBuilder.Embedded/Building/Builder.cs
+++ b/src/Umbraco.ModelsBuilder.Embedded/Building/Builder.cs
@@ -26,14 +26,11 @@ namespace Umbraco.ModelsBuilder.Embedded.Building
         protected readonly IList<string> TypesUsing = new List<string>
         {
             "System",
-            "System.Collections.Generic",
             "System.Linq.Expressions",
-            "System.Web",
-            "Umbraco.Core.Models",
             "Umbraco.Core.Models.PublishedContent",
-            "Umbraco.Web",
             "Umbraco.Web.PublishedCache",
-            "Umbraco.ModelsBuilder.Embedded"
+            "Umbraco.ModelsBuilder.Embedded",
+            "Umbraco.Core"
         };
 
         /// <summary>
diff --git a/src/Umbraco.ModelsBuilder.Embedded/Building/ModelsGenerator.cs b/src/Umbraco.ModelsBuilder.Embedded/Building/ModelsGenerator.cs
index 648a2e76fa..587e1a6bc4 100644
--- a/src/Umbraco.ModelsBuilder.Embedded/Building/ModelsGenerator.cs
+++ b/src/Umbraco.ModelsBuilder.Embedded/Building/ModelsGenerator.cs
@@ -1,7 +1,7 @@
 using System.IO;
 using System.Text;
 using Umbraco.Core.Configuration;
-using Umbraco.Core.IO;
+using Umbraco.Core.Hosting;
 
 namespace Umbraco.ModelsBuilder.Embedded.Building
 {
@@ -10,19 +10,19 @@ namespace Umbraco.ModelsBuilder.Embedded.Building
         private readonly UmbracoServices _umbracoService;
         private readonly IModelsBuilderConfig _config;
         private readonly OutOfDateModelsStatus _outOfDateModels;
-        private readonly IIOHelper _ioHelper;
+        private readonly IHostingEnvironment _hostingEnvironment;
 
-        public ModelsGenerator(UmbracoServices umbracoService, IModelsBuilderConfig config, OutOfDateModelsStatus outOfDateModels, IIOHelper ioHelper)
+        public ModelsGenerator(UmbracoServices umbracoService, IModelsBuilderConfig config, OutOfDateModelsStatus outOfDateModels, IHostingEnvironment hostingEnvironment)
         {
             _umbracoService = umbracoService;
             _config = config;
             _outOfDateModels = outOfDateModels;
-            _ioHelper = ioHelper;
+            _hostingEnvironment = hostingEnvironment;
         }
 
         internal void GenerateModels()
         {
-            var modelsDirectory = _config.ModelsDirectoryAbsolute(_ioHelper);
+            var modelsDirectory = _config.ModelsDirectoryAbsolute(_hostingEnvironment);
             if (!Directory.Exists(modelsDirectory))
                 Directory.CreateDirectory(modelsDirectory);
 
diff --git a/src/Umbraco.ModelsBuilder.Embedded/Building/TextBuilder.cs b/src/Umbraco.ModelsBuilder.Embedded/Building/TextBuilder.cs
index e218a2da5f..abd5bcb85b 100644
--- a/src/Umbraco.ModelsBuilder.Embedded/Building/TextBuilder.cs
+++ b/src/Umbraco.ModelsBuilder.Embedded/Building/TextBuilder.cs
@@ -191,9 +191,10 @@ namespace Umbraco.ModelsBuilder.Embedded.Building
                 type.ClrName);
             sb.Append("\t\t\t=> PublishedModelUtility.GetModelPropertyType(GetModelContentType(publishedSnapshotAccessor), selector);\n");
             sb.Append("#pragma warning restore 0109\n\n");
+            sb.Append("private IPublishedValueFallback _publishedValueFallback;");
 
             // write the ctor
-            sb.AppendFormat("\t\t// ctor\n\t\tpublic {0}(IPublished{1} content)\n\t\t\t: base(content)\n\t\t{{ }}\n\n",
+            sb.AppendFormat("\t\t// ctor\n\t\tpublic {0}(IPublished{1} content, IPublishedValueFallback publishedValueFallback)\n\t\t\t: base(content)\n\t\t{{\n _publishedValueFallback = publishedValueFallback; \n}}\n\n",
                 type.ClrName, type.IsElement ? "Element" : "Content");
 
             // write the properties
@@ -324,7 +325,7 @@ namespace Umbraco.ModelsBuilder.Embedded.Building
                     WriteClrType(sb, property.ClrTypeName);
                     sb.Append(">");
                 }
-                sb.AppendFormat("(\"{0}\");\n",
+                sb.AppendFormat("(_publishedValueFallback, \"{0}\");\n",
                     property.Alias);
             }
 
diff --git a/src/Umbraco.ModelsBuilder.Embedded/ModelsGenerationError.cs b/src/Umbraco.ModelsBuilder.Embedded/ModelsGenerationError.cs
index f8f6e8c7bc..e4b5da0a98 100644
--- a/src/Umbraco.ModelsBuilder.Embedded/ModelsGenerationError.cs
+++ b/src/Umbraco.ModelsBuilder.Embedded/ModelsGenerationError.cs
@@ -2,6 +2,7 @@
 using System.IO;
 using System.Text;
 using Umbraco.Core.Configuration;
+using Umbraco.Core.Hosting;
 using Umbraco.Core.IO;
 
 namespace Umbraco.ModelsBuilder.Embedded
@@ -9,12 +10,12 @@ namespace Umbraco.ModelsBuilder.Embedded
     public sealed class ModelsGenerationError
     {
         private readonly IModelsBuilderConfig _config;
-        private readonly IIOHelper _ioHelper;
+        private readonly IHostingEnvironment _hostingEnvironment;
 
-        public ModelsGenerationError(IModelsBuilderConfig config, IIOHelper ioHelper)
+        public ModelsGenerationError(IModelsBuilderConfig config, IHostingEnvironment hostingEnvironment)
         {
             _config = config;
-            _ioHelper = ioHelper;
+            _hostingEnvironment = hostingEnvironment;
         }
 
         public void Clear()
@@ -59,7 +60,7 @@ namespace Umbraco.ModelsBuilder.Embedded
 
         private string GetErrFile()
         {
-            var modelsDirectory = _config.ModelsDirectoryAbsolute(_ioHelper);
+            var modelsDirectory = _config.ModelsDirectoryAbsolute(_hostingEnvironment);
             if (!Directory.Exists(modelsDirectory))
                 return null;
 
diff --git a/src/Umbraco.ModelsBuilder.Embedded/OutOfDateModelsStatus.cs b/src/Umbraco.ModelsBuilder.Embedded/OutOfDateModelsStatus.cs
index b8105eeef2..0f034c04bc 100644
--- a/src/Umbraco.ModelsBuilder.Embedded/OutOfDateModelsStatus.cs
+++ b/src/Umbraco.ModelsBuilder.Embedded/OutOfDateModelsStatus.cs
@@ -1,5 +1,6 @@
 using System.IO;
 using Umbraco.Core.Configuration;
+using Umbraco.Core.Hosting;
 using Umbraco.Core.IO;
 using Umbraco.Web.Cache;
 
@@ -8,12 +9,12 @@ namespace Umbraco.ModelsBuilder.Embedded
     public sealed class OutOfDateModelsStatus
     {
         private readonly IModelsBuilderConfig _config;
-        private readonly IIOHelper _ioHelper;
+        private readonly IHostingEnvironment _hostingEnvironment;
 
-        public OutOfDateModelsStatus(IModelsBuilderConfig config, IIOHelper ioHelper)
+        public OutOfDateModelsStatus(IModelsBuilderConfig config, IHostingEnvironment hostingEnvironment)
         {
             _config = config;
-            _ioHelper = ioHelper;
+            _hostingEnvironment = hostingEnvironment;
         }
 
         internal void Install()
@@ -28,7 +29,7 @@ namespace Umbraco.ModelsBuilder.Embedded
 
         private string GetFlagPath()
         {
-            var modelsDirectory = _config.ModelsDirectoryAbsolute(_ioHelper);
+            var modelsDirectory = _config.ModelsDirectoryAbsolute(_hostingEnvironment);
             if (!Directory.Exists(modelsDirectory))
                 Directory.CreateDirectory(modelsDirectory);
             return Path.Combine(modelsDirectory, "ood.flag");
diff --git a/src/Umbraco.ModelsBuilder.Embedded/PureLiveModelFactory.cs b/src/Umbraco.ModelsBuilder.Embedded/PureLiveModelFactory.cs
index 7809d2bf48..bc419bece4 100644
--- a/src/Umbraco.ModelsBuilder.Embedded/PureLiveModelFactory.cs
+++ b/src/Umbraco.ModelsBuilder.Embedded/PureLiveModelFactory.cs
@@ -9,8 +9,6 @@ using System.Text;
 using System.Text.RegularExpressions;
 using System.Threading;
 using System.Web;
-using System.Web.Compilation;
-using System.Web.WebPages.Razor;
 using Umbraco.Core.Configuration;
 using Umbraco.Core;
 using Umbraco.Core.Hosting;
@@ -19,6 +17,7 @@ using Umbraco.Core.Logging;
 using Umbraco.Core.Models.PublishedContent;
 using Umbraco.ModelsBuilder.Embedded.Building;
 using File = System.IO.File;
+using Umbraco.Core.Composing;
 
 namespace Umbraco.ModelsBuilder.Embedded
 {
@@ -33,18 +32,21 @@ namespace Umbraco.ModelsBuilder.Embedded
         private readonly FileSystemWatcher _watcher;
         private int _ver, _skipver;
         private readonly int _debugLevel;
-        private BuildManager _theBuildManager;
+        private RoslynCompiler _roslynCompiler;
         private readonly Lazy<UmbracoServices> _umbracoServices; // fixme: this is because of circular refs :(
         private UmbracoServices UmbracoServices => _umbracoServices.Value;
 
         private static readonly Regex AssemblyVersionRegex = new Regex("AssemblyVersion\\(\"[0-9]+.[0-9]+.[0-9]+.[0-9]+\"\\)", RegexOptions.Compiled);
         private const string ProjVirt = "~/App_Data/Models/all.generated.cs";
+        private const string CodeGen = "~/App_Data/Models/";
         private static readonly string[] OurFiles = { "models.hash", "models.generated.cs", "all.generated.cs", "all.dll.path", "models.err" };
 
         private readonly IModelsBuilderConfig _config;
+        private readonly IHostingEnvironment _hostingEnvironment;
         private readonly IApplicationShutdownRegistry _hostingLifetime;
-        private readonly IIOHelper _ioHelper;
         private readonly ModelsGenerationError _errors;
+        private readonly ITypeFinder _typeFinder;
+        private readonly IPublishedValueFallback _publishedValueFallback;
 
         public PureLiveModelFactory(
             Lazy<UmbracoServices> umbracoServices,
@@ -52,22 +54,25 @@ namespace Umbraco.ModelsBuilder.Embedded
             IModelsBuilderConfig config,
             IHostingEnvironment hostingEnvironment,
             IApplicationShutdownRegistry hostingLifetime,
-            IIOHelper ioHelper)
+            ITypeFinder typeFinder,
+            IPublishedValueFallback publishedValueFallback)
         {
             _umbracoServices = umbracoServices;
             _logger = logger;
             _config = config;
+            _hostingEnvironment = hostingEnvironment;
             _hostingLifetime = hostingLifetime;
-            _ioHelper = ioHelper;
-            _errors = new ModelsGenerationError(config, ioHelper);
+            _typeFinder = typeFinder;
+            _publishedValueFallback = publishedValueFallback;
+            _errors = new ModelsGenerationError(config, _hostingEnvironment);
             _ver = 1; // zero is for when we had no version
             _skipver = -1; // nothing to skip
 
-            RazorBuildProvider.CodeGenerationStarted += RazorBuildProvider_CodeGenerationStarted;
+            // RazorBuildProvider.CodeGenerationStarted += RazorBuildProvider_CodeGenerationStarted;
 
             if (!hostingEnvironment.IsHosted) return;
 
-            var modelsDirectory = _config.ModelsDirectoryAbsolute(_ioHelper);
+            var modelsDirectory = _config.ModelsDirectoryAbsolute(_hostingEnvironment);
             if (!Directory.Exists(modelsDirectory))
                 Directory.CreateDirectory(modelsDirectory);
 
@@ -113,7 +118,7 @@ namespace Umbraco.ModelsBuilder.Embedded
             infos.TryGetValue(contentTypeAlias, out var info);
 
             // create model
-            return info == null ? element : info.Ctor(element);
+            return info == null ? element : info.Ctor(element, _publishedValueFallback);
         }
 
         // this runs only once the factory is ready
@@ -200,13 +205,14 @@ namespace Umbraco.ModelsBuilder.Embedded
 
                 if (_debugLevel > 0)
                     _logger.Debug<PureLiveModelFactory>("RazorBuildProvider.CodeGenerationStarted");
-                if (!(sender is RazorBuildProvider provider)) return;
+                // TODO: How to handle this? 
+                // if (!(sender is RazorBuildProvider provider)) return;
 
                 // add the assembly, and add a dependency to a text file that will change on each
                 // compilation as in some environments (could not figure which/why) the BuildManager
                 // would not re-compile the views when the models assembly is rebuilt.
-                provider.AssemblyBuilder.AddAssemblyReference(_modelsAssembly);
-                provider.AddVirtualPathDependency(ProjVirt);
+                //provider.AssemblyBuilder.AddAssemblyReference(_modelsAssembly);
+                //provider.AddVirtualPathDependency(ProjVirt);
             }
             finally
             {
@@ -227,7 +233,7 @@ namespace Umbraco.ModelsBuilder.Embedded
                 _hasModels = false;
                 _pendingRebuild = true;
 
-                var modelsDirectory = _config.ModelsDirectoryAbsolute(_ioHelper);
+                var modelsDirectory = _config.ModelsDirectoryAbsolute(_hostingEnvironment);
                 if (!Directory.Exists(modelsDirectory))
                     Directory.CreateDirectory(modelsDirectory);
 
@@ -248,16 +254,13 @@ namespace Umbraco.ModelsBuilder.Embedded
         }
 
         // gets "the" build manager
-        private BuildManager TheBuildManager
+        private RoslynCompiler RoslynCompiler
         {
             get
             {
-                if (_theBuildManager != null) return _theBuildManager;
-                var prop = typeof(BuildManager).GetProperty("TheBuildManager", BindingFlags.NonPublic | BindingFlags.Static);
-                if (prop == null)
-                    throw new InvalidOperationException("Could not get BuildManager.TheBuildManager property.");
-                _theBuildManager = (BuildManager)prop.GetValue(null);
-                return _theBuildManager;
+                if (_roslynCompiler != null) return _roslynCompiler;
+                _roslynCompiler = new RoslynCompiler(System.Runtime.Loader.AssemblyLoadContext.All.SelectMany(x => x.Assemblies));
+                return _roslynCompiler;
             }
         }
 
@@ -285,7 +288,7 @@ namespace Umbraco.ModelsBuilder.Embedded
             {
                 // always take the BuildManager lock *before* taking the _locker lock
                 // to avoid possible deadlock situations (see notes above)
-                Monitor.Enter(TheBuildManager, ref buildManagerLocked);
+                Monitor.Enter(RoslynCompiler, ref buildManagerLocked);
 
                 _locker.EnterUpgradeableReadLock();
 
@@ -343,13 +346,13 @@ namespace Umbraco.ModelsBuilder.Embedded
                 if (_locker.IsUpgradeableReadLockHeld)
                     _locker.ExitUpgradeableReadLock();
                 if (buildManagerLocked)
-                    Monitor.Exit(TheBuildManager);
+                    Monitor.Exit(RoslynCompiler);
             }
         }
 
         private Assembly GetModelsAssembly(bool forceRebuild)
         {
-            var modelsDirectory = _config.ModelsDirectoryAbsolute(_ioHelper);
+            var modelsDirectory = _config.ModelsDirectoryAbsolute(_hostingEnvironment);
             if (!Directory.Exists(modelsDirectory))
                 Directory.CreateDirectory(modelsDirectory);
 
@@ -402,7 +405,7 @@ namespace Umbraco.ModelsBuilder.Embedded
                 if (File.Exists(dllPathFile))
                 {
                     var dllPath = File.ReadAllText(dllPathFile);
-                    var codegen = HttpRuntime.CodegenDir;
+                    var codegen = CodeGen;
 
                     _logger.Debug<PureLiveModelFactory>($"Cached models dll at {dllPath}.");
 
@@ -452,7 +455,7 @@ namespace Umbraco.ModelsBuilder.Embedded
                 _ver++;
                 try
                 {
-                    assembly = BuildManager.GetCompiledAssembly(ProjVirt);
+                    assembly = RoslynCompiler.GetCompiledAssembly(_hostingEnvironment.MapPathContentRoot(ProjVirt), Path.Combine(_hostingEnvironment.ApplicationPhysicalPath, "App_Data", $"generated.cs.{currentHash}.dll"));
                     File.WriteAllText(dllPathFile, assembly.Location);
                 }
                 catch
@@ -490,7 +493,7 @@ namespace Umbraco.ModelsBuilder.Embedded
             // compile and register
             try
             {
-                assembly = BuildManager.GetCompiledAssembly(ProjVirt);
+                assembly = RoslynCompiler.GetCompiledAssembly(_hostingEnvironment.MapPathContentRoot(ProjVirt), Path.Combine(_hostingEnvironment.ApplicationPhysicalPath, "App_Data", $"generated.cs.{currentHash}.dll"));
                 File.WriteAllText(dllPathFile, assembly.Location);
                 File.WriteAllText(modelsHashFile, currentHash);
             }
@@ -523,7 +526,7 @@ namespace Umbraco.ModelsBuilder.Embedded
 
         private static Infos RegisterModels(IEnumerable<Type> types)
         {
-            var ctorArgTypes = new[] { typeof(IPublishedElement) };
+            var ctorArgTypes = new[] { typeof(IPublishedElement), typeof(IPublishedValueFallback) };
             var modelInfos = new Dictionary<string, ModelInfo>(StringComparer.InvariantCultureIgnoreCase);
             var map = new Dictionary<string, Type>();
 
@@ -535,7 +538,7 @@ namespace Umbraco.ModelsBuilder.Embedded
                 foreach (var ctor in type.GetConstructors())
                 {
                     var parms = ctor.GetParameters();
-                    if (parms.Length == 1 && typeof(IPublishedElement).IsAssignableFrom(parms[0].ParameterType))
+                    if (parms.Length == 2 && typeof(IPublishedElement).IsAssignableFrom(parms[0].ParameterType) && typeof(IPublishedValueFallback).IsAssignableFrom(parms[1].ParameterType))
                     {
                         if (constructor != null)
                             throw new InvalidOperationException($"Type {type.FullName} has more than one public constructor with one argument of type, or implementing, IPropertySet.");
@@ -562,7 +565,7 @@ namespace Umbraco.ModelsBuilder.Embedded
                 gen.Emit(OpCodes.Ldarg_0);
                 gen.Emit(OpCodes.Newobj, constructor);
                 gen.Emit(OpCodes.Ret);
-                var func = (Func<IPublishedElement, IPublishedElement>)meth.CreateDelegate(typeof(Func<IPublishedElement, IPublishedElement>));
+                var func = (Func<IPublishedElement, IPublishedValueFallback, IPublishedElement>)meth.CreateDelegate(typeof(Func<IPublishedElement, IPublishedValueFallback, IPublishedElement>));
 
                 modelInfos[typeName] = new ModelInfo { ParameterType = parameterType, Ctor = func, ModelType = type };
                 map[typeName] = type;
@@ -573,7 +576,7 @@ namespace Umbraco.ModelsBuilder.Embedded
 
         private string GenerateModelsCode(IList<TypeModel> typeModels)
         {
-            var modelsDirectory = _config.ModelsDirectoryAbsolute(_ioHelper);
+            var modelsDirectory = _config.ModelsDirectoryAbsolute(_hostingEnvironment);
             if (!Directory.Exists(modelsDirectory))
                 Directory.CreateDirectory(modelsDirectory);
 
@@ -651,7 +654,7 @@ namespace Umbraco.ModelsBuilder.Embedded
         internal class ModelInfo
         {
             public Type ParameterType { get; set; }
-            public Func<IPublishedElement, IPublishedElement> Ctor { get; set; }
+            public Func<IPublishedElement, IPublishedValueFallback, IPublishedElement> Ctor { get; set; }
             public Type ModelType { get; set; }
             public Func<IList> ListCtor { get; set; }
         }
diff --git a/src/Umbraco.ModelsBuilder.Embedded/ReferencedAssemblies.cs b/src/Umbraco.ModelsBuilder.Embedded/ReferencedAssemblies.cs
index 596e63d8e1..7094f3fd38 100644
--- a/src/Umbraco.ModelsBuilder.Embedded/ReferencedAssemblies.cs
+++ b/src/Umbraco.ModelsBuilder.Embedded/ReferencedAssemblies.cs
@@ -9,12 +9,12 @@ namespace Umbraco.ModelsBuilder.Embedded
     internal static class ReferencedAssemblies
     {
         private static readonly Lazy<IEnumerable<string>> LazyLocations;
-
+        // TODO: Do we even use this anymore?
         static ReferencedAssemblies()
         {
-            LazyLocations = new Lazy<IEnumerable<string>>(() => Current.HostingEnvironment.IsHosted // fixme inject!
-                ? GetAllReferencedAssembliesLocationFromBuildManager()
-                : GetAllReferencedAssembliesFromDomain());
+            //LazyLocations = new Lazy<IEnumerable<string>>(() => Current.HostingEnvironment.IsHosted // fixme inject!
+            //    ? GetAllReferencedAssembliesLocationFromBuildManager()
+            //    : GetAllReferencedAssembliesFromDomain());
         }
 
         /// <summary>
@@ -26,7 +26,7 @@ namespace Umbraco.ModelsBuilder.Embedded
         public static Assembly GetNetStandardAssembly(List<Assembly> assemblies)
         {
             if (assemblies == null)
-                assemblies = BuildManager.GetReferencedAssemblies().Cast<Assembly>().ToList();
+                //assemblies = BuildManager.GetReferencedAssemblies().Cast<Assembly>().ToList();
 
             // for some reason, netstandard is also missing from BuildManager.ReferencedAssemblies and yet, is part of
             // the references that CSharpCompiler (above) receives - where is it coming from? cannot figure it out
@@ -60,34 +60,34 @@ namespace Umbraco.ModelsBuilder.Embedded
         }
 
         // hosted, get referenced assemblies from the BuildManager and filter
-        private static IEnumerable<string> GetAllReferencedAssembliesLocationFromBuildManager()
-        {
-            var assemblies = BuildManager.GetReferencedAssemblies().Cast<Assembly>().ToList();
+        //private static IEnumerable<string> GetAllReferencedAssembliesLocationFromBuildManager()
+        //{
+        //    //var assemblies = BuildManager.GetReferencedAssemblies().Cast<Assembly>().ToList();
 
-            assemblies.Add(typeof(ReferencedAssemblies).Assembly); // always include ourselves
+        //    assemblies.Add(typeof(ReferencedAssemblies).Assembly); // always include ourselves
 
-            // see https://github.com/aspnet/RoslynCodeDomProvider/blob/master/src/Microsoft.CodeDom.Providers.DotNetCompilerPlatform/CSharpCompiler.cs:
-            // mentions "Bug 913691: Explicitly add System.Runtime as a reference."
-            // and explicitly adds System.Runtime to references before invoking csc.exe
-            // so, doing the same here
-            try
-            {
-                var systemRuntime = Assembly.Load("System.Runtime, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a");
-                assemblies.Add(systemRuntime);
-            }
-            catch { /* never mind */ }
+        //    // see https://github.com/aspnet/RoslynCodeDomProvider/blob/master/src/Microsoft.CodeDom.Providers.DotNetCompilerPlatform/CSharpCompiler.cs:
+        //    // mentions "Bug 913691: Explicitly add System.Runtime as a reference."
+        //    // and explicitly adds System.Runtime to references before invoking csc.exe
+        //    // so, doing the same here
+        //    try
+        //    {
+        //        var systemRuntime = Assembly.Load("System.Runtime, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a");
+        //        assemblies.Add(systemRuntime);
+        //    }
+        //    catch { /* never mind */ }
 
-            // for some reason, netstandard is also missing from BuildManager.ReferencedAssemblies and yet, is part of
-            // the references that CSharpCompiler (above) receives - where is it coming from? cannot figure it out
-            var netStandard = GetNetStandardAssembly(assemblies);
-            if (netStandard != null) assemblies.Add(netStandard);
+        //    // for some reason, netstandard is also missing from BuildManager.ReferencedAssemblies and yet, is part of
+        //    // the references that CSharpCompiler (above) receives - where is it coming from? cannot figure it out
+        //    var netStandard = GetNetStandardAssembly(assemblies);
+        //    if (netStandard != null) assemblies.Add(netStandard);
 
-            return assemblies
-                .Where(x => !x.IsDynamic && !x.Location.IsNullOrWhiteSpace())
-                .Select(x => x.Location)
-                .Distinct()
-                .ToList();
-        }
+        //    return assemblies
+        //        .Where(x => !x.IsDynamic && !x.Location.IsNullOrWhiteSpace())
+        //        .Select(x => x.Location)
+        //        .Distinct()
+        //        .ToList();
+        //}
 
         // non-hosted, do our best
         private static IEnumerable<string> GetAllReferencedAssembliesFromDomain()
diff --git a/src/Umbraco.ModelsBuilder.Embedded/RoslynCompiler.cs b/src/Umbraco.ModelsBuilder.Embedded/RoslynCompiler.cs
index 43a9202c13..ed9c013236 100644
--- a/src/Umbraco.ModelsBuilder.Embedded/RoslynCompiler.cs
+++ b/src/Umbraco.ModelsBuilder.Embedded/RoslynCompiler.cs
@@ -5,6 +5,7 @@ using Microsoft.CodeAnalysis.Text;
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Reflection;
 using System.Text;
 
@@ -14,21 +15,38 @@ namespace Umbraco.ModelsBuilder.Embedded
     {
         private OutputKind _outputKind;
         private CSharpParseOptions _parseOptions;
+        private List<MetadataReference> _refs;
 
-        public RoslynCompiler()
+        public RoslynCompiler(IEnumerable<Assembly> referenceAssemblies)
         {
             _outputKind = OutputKind.DynamicallyLinkedLibrary;
             _parseOptions = CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.Latest);  // What languageversion should we default to?
+
+            // The references should be the same every time GetCompiledAssembly is called
+            // Making it kind of a waste to convert the Assembly types into MetadataReference
+            // every time GetCompiledAssembly is called, so that's why I do it in the ctor
+            _refs = new List<MetadataReference>();
+            foreach(var assembly in referenceAssemblies.Where(x => !x.IsDynamic && !string.IsNullOrWhiteSpace(x.Location)))
+            {
+                _refs.Add(MetadataReference.CreateFromFile(assembly.Location));
+            };
+
+            // Might have to do this another way, see
+            // see https://github.com/aspnet/RoslynCodeDomProvider/blob/master/src/Microsoft.CodeDom.Providers.DotNetCompilerPlatform/CSharpCompiler.cs:
+            // mentions "Bug 913691: Explicitly add System.Runtime as a reference."
+            // and explicitly adds System.Runtime to references before invoking csc.exe
+            _refs.Add(MetadataReference.CreateFromFile(typeof(System.Runtime.AssemblyTargetedPatchBandAttribute).Assembly.Location));
+            _refs.Add(MetadataReference.CreateFromFile(typeof(object).Assembly.Location));
+            _refs.Add(MetadataReference.CreateFromFile(typeof(System.CodeDom.Compiler.GeneratedCodeAttribute).Assembly.Location));
         }
 
-        public Assembly GetCompiledAssembly(string pathToSourceFile, IEnumerable<MetadataReference> refs)
+        public Assembly GetCompiledAssembly(string pathToSourceFile, string saveLocation)
         {
             // TODO: Get proper temp file location/filename
-            var outputPath = $"generated.cs.{Guid.NewGuid()}.dll";
             var sourceCode = File.ReadAllText(pathToSourceFile);
 
-            CompileToFile(outputPath, sourceCode, "ModelsGenerated", refs);
-            return Assembly.LoadFile(outputPath);
+            CompileToFile(saveLocation, sourceCode, "ModelsGeneratedAssembly", _refs);
+            return Assembly.LoadFile(saveLocation);
 
         } 
 
@@ -46,7 +64,8 @@ namespace Umbraco.ModelsBuilder.Embedded
                 // Not entirely certain that assemblyIdentityComparer is nececary? 
                 assemblyIdentityComparer: DesktopAssemblyIdentityComparer.Default));
 
-            compilation.Emit(outputFile);
+            var result = compilation.Emit(outputFile);
+
         }
     }
 }
diff --git a/src/Umbraco.Web.UI.NetCore/Umbraco.Web.UI.NetCore.csproj b/src/Umbraco.Web.UI.NetCore/Umbraco.Web.UI.NetCore.csproj
index 40ed5a8093..0feb289806 100644
--- a/src/Umbraco.Web.UI.NetCore/Umbraco.Web.UI.NetCore.csproj
+++ b/src/Umbraco.Web.UI.NetCore/Umbraco.Web.UI.NetCore.csproj
@@ -98,6 +98,7 @@
         <Content Remove="Umbraco\PartialViewMacros\Templates\EditProfile.cshtml" />
     </ItemGroup>
 
+    <ItemGroup>
         <Content Remove="App_Data\**" />
     </ItemGroup>