Detached garages have their benefits. However they may not be the ideal thing for you. Here are some of the advantages and disadvantages of building a detached garage as opposed to an attached one to help you make a decision.
Detached Garages - Pros
The noise from a detached garage will not travel to your property. This is especially useful if you have ongoing projects such as woodwork or vehicle maintenance that can be intrusive. A detached garage may also be easier to construct as you won't have to worry about how it attaches to your property.
Detached Garages - Cons
If you are building a detached garage, you first need enough space to do so. This can be an issue if you live in a suburban area. You will also find that it is more expensive in building materials than an attached garage as you will need to build an extra wall and also purchase extra paint and weather-proofing.
If you are building a detached garage, you will need to remember that you won't have direct access to your property from it. You may also consider this to be a security issue if you are storing equipment or tools in your garage that can be valuable.