IMPORTANT – this does not work afterall – still looking for solution.
You can alter the Project Server Site Template just like you can alter any other SharePoint Site and make your futures sites with your own custom template. You have to watch out for the gotchas which are mainly around the Risks, Issues and Deliverables lists but the workaround is simple; do not delete or rename these lists nor any associated fields and you should be safe to make changes to suit. This article is not about the gotchas but is about how you can alter the out of box permissions to suit your business. What is a no code alteration? Is defined as any change you may want to make to a site or a sub-site using the SharePoint User Interface (UI).The basic process to alter and deploy no-code changes is the same whether it is for permissions, new lists, adding default list data or standard document templates or whatever is necessary for your Project Management Processes.
We are now going to show you how to change the Project Site security model to allow Project Managers to create sub-sites and/or meeting workspaces. The out of box project site does not inherit permissions from the parent PWA site collection allowing you to change the security model with out causing unforeseen security issues. The whole process is quite simple but has many steps.
1. Create a dummy project and site via PWA or Project Pro. We can delete it later when we are finished or you can keep the template and make further changes for another deployment at a later time.
2. Launch the site, choose > Site Actions > Site Permissions and click on Permission Levels button on Ribbon > Click on the Project Managers Link to launch the Permission Level Form
3. Scroll down the Permission level Page until you find the Permission under Site Permissions Heading called Create Sub-Sites. Check off the box and click Submit button on bottom of page. see graphics below.
4. Now we need to deploy the template so that all future sites will be created with this new permission setting. Choose Site Settings > Site Actions heading > Save Site as Template > Enter name to suit and click Ok. You can also include content, meaning that if you add data or documents to the lists and libraries that content will show up in each new future site.
5. Configure Project Server to respect the new template. Go back to PWA, choose Server Settings > Site Provisioning Settings and pick the new template from the pick list and save changes.
6. If you use Enterprise Project types and PDP pages such as the Basic Project Plan Type, you will need to set your new Template as default for new Sites that are created from PWA. Choose Server Settings, Project detail pages and click on Basic Project Plan and choose new template per graphic below.
7. The last step is to re-start IIS, open Powershell window or command prompt and enter IISreset. Now create a new project and site and check to ensure your new site was created with you new changes.