How to re-include excluded folder in SSDT-BI / Visual Studio 2013 database project?
This is actually fairly easy to do. Do not re-create the folder.

With Visual Studio open and the solution loaded, do the following:


View the Solution Explorer (shows on the right side).
Select either the project or any of the folders or items within the project.
In the top button bar within Solution Explorer, click on the &gt;&gt; button on the far right. Three or four new buttons should appear below your cursor (depending on what type of item you had selected).
The far left button in the new set that appeared when you clicked the &gt;&gt; is for Show All Files. Click that. You should now see folders and files, etc that are dotted outline icons instead of solid shapes.
Right click on the folder that was previously excluded from the project.
Select Include In Project.
In the top button bar within Solution Explorer, click on the &gt;&gt; button on the far right. Three or four new buttons should appear below your cursor (depending on what type of item you had selected).
The far left button in the new set that appeared when you clicked the &gt;&gt; should already be selected. Click that to re-hide all of the folders and files, etc with the dotted outline icons.