I would like to know why you decided to build your own framework in your company.By framework, I don't mean few libraries you use often. I mean a specific way of building applications on top of it, with base classes, convention, etc.So why did you built your own framework? How could you justify that to the person that employs you. Have you measure the positive and negative impact of it?Regarding your experiences, did you notice that in some case a company framework produced real benefits, or on the other hand, increased costs of development (learning curve, debugging, maintenance, ...)? 
When is it more productive to build your own framework than to use an existing one?
frameworks
Answer to why:License issuesCompany specific requirements that didnt exist in current frameworksThe company wants to have control over support and maintenance of the frameworkThe architect didn't know better! He/she didn't know about that specific framework existed, so they decided to reinvent the wheel.Update:Enterprises prefer to reinvent the wheel rather than using small frameworks. By small I refer to framework that may have uncertain future. For example.NET framework is more secure choose for enterprises than a framework created by a small community. Enterprises need security because many of their application are business critical and also long lived. The cost of reinventing the wheel may be more in short terms. But the cost may be more if framework used in company application is deprecated and no longer supported, or licenses are changed. Here the company may have to throw out the current framework and put in another one.Visual Basic is a good example of a language that is no longer support by Microsoft. And this cost companies billions since they have to start over with new development.