While I plan on asking at work to see if there is an official policy, I wonder in general. If you're working on a non-work application on a work computer, who owns that application? Work, or you?
It will most likely be stated in your contract of employment. Best to check with your HR department on company policy.
Usually, if you're working in an IT company, your HR department is smart enough to say that anything developed on company property belongs to the company. Do check your employee handbook.
This is a very foolish idea. If I was you, I would get that stuff off the company machines as quickly as possible and try to remove all traces of it.
Your company would have pretty good cause to both claim all your work as their own (since it was developed with company resources) and to fire you for misuse of said resources.
The chance of there being an official company policy that work done with their resources is not theirs, is slim to none. That's because they gain nothing from such a policy but it costs them. Why would they do that?
I keep every piece of my non-company work well away from their machines and I made sure that my employment contract was modified to state that stuff done outside company hours on non-company resources was entirely mine.
If you cannot retroactively modify your employment contract, get written advice from a company representative that you're allowed to work on outside products on your time and with your equipment, without the company having a claim. That would be a good start.
If you can't get such a declaration then there may be other ways to mitigate the possible damage but they will depend entirely on your legal jurisdiction. One method I've seen used is to have another company do the work and you just work for that company (the company was a $2 shelf company owned by the developers, I'm not talking about cutting some sort of back-door deal with Microsoft here). The employment contract with that company was very explicit that all work was owned by the company and nothing in the original employment contract stated that the employee couldn't work two jobs.
Whether that would work in your jurisdiction (or even whether it would work when it went to the courts here), I have no idea. You'd need to consult a local lawyer.
This is not legal advice. I am not a lawyer. I am not your lawyer. I am not licensed to practice in your (or any) jurisdiction. I know a few lawyers and they're not bad blokes, when they're not trying to sell your body parts on the black market :-) This advice is general in nature and you should treat it as being worth every cent you paid for it (which is none).