Edit Page option missing on default page

Scenario:
I was asked to develop a small sharepoint website with 2-3 basic pages and of-course default.aspx. So I created a Document Library with the name Pages and created some extra pages in it.

Also I was suppose to give access to another team member to add content to the pages.. like editing the page .. adding the web parts and content to it.

Now comes the situation, the guy who was suppose to add web parts and edit the page told me that he get Edit Page option on all the other pages except Default.aspx

Solution:
I realized that Default.aspx is different from other pages because of its location within the site and it sounded like something wrong with his permissions.

So after some googling I found that , you need following permissions to do certain activity.

Permission : Add and Customize Pages
Details : Without this permission, you cannot edit files at the root of the site (such as default.aspx in a team site) or files that reside in folders outside of lists and libraries.

Permission : Browse Directories
Details : Without this permission, you cannot open a site in SharePoint Designer.

Permission : Manage Lists
Details : Without this permission, you cannot delete libraries, lists, or list forms or views (such as AllItems.aspx) in SharePoint Designer. However, if a list does not inherit permissions from the site, the list permissions apply to that specific list. Note that by default, the Workflows document library does not inherit permissions from the site; you must manage these permissions separately.

Article:
SharePoint Designer Permissions