If you have a garage roof that contains asbestos then you need to be very carful about what you do to it. If you need repairs doing or if you want a new roof you may need to get a specialist company in who is trained in removing asbestos. Asbestos is now known to be very dangerous and inhaling it can cause to a long term health issues with can be fatal.
If you are considering having a garage extension done which will require work on the roof then you will need to bear this in mind as it can add a lot on to the cost of the job.
Whenever you need a company to work with asbestos you need to ensure that they are qualified to do it. Find out from your local council what you need to do to ensure that it is removed and disposed of properly.
If you have a leak then you may be able to patch up the repair but this isn’t really a long term solution and isn’t advisable if you can help it. It may be time to bite the bullet and replace the roof so ou know you do not have to worry about it again in the future.