Adjective or Present Participle

I was wondering if it's correct to refer to a 'leaking roof'.

I thought that it should be a 'leaky roof' or a 'roof that is leaking' since leaking is the present participle.

When I did a search on google I found out that a lot of people actually talk about a 'leaking roof'.

Is this actually correct or is it a case of people simply using poor grammar?

Thanks!