Let’s start by stating the clear, the usability of your garage with respect to your automobile depends on the size of your automobile. If not built with a 16′ rated beam, then a portion of siding and ceiling drywall would have to be removed, the complete side of the house over the garage doors would have to be supported on a short-term wall, the garage doors removed, the beams and center post removed, the outer posts beefed up, the new beam installed, floor joists tied into it, door jamb and trim pices installed, siding and drywall replaced and painted, and a new garage door installed.
These expenses are based on a specification that contains basic dimensions of 6m (wide) x 6m (deep) x two.5m (higher), a shallow pitched (25°) concrete tiled roof, half brick-thick external walls with brick piers, a simple ground floor slab and trench fill foundations (to a normal 1m depth).
Regular sizes start off at roughly 3m (10ft) x 6m (20ft) and double garages at 6m (20ft) x 6m. A standard garage with block/brick external finish with a timber and concrete tiled roof built by a competent experienced builder would cost about €12,000 for a single garage or €22,000 for a double.
Note he will virtually undoubtedly have to reduce a couple of head-sized drywall holes in your ceiling to see what is there and get measurements, so that repair cost if the job is not gone ahead with would be about $200 or so. No noticeable added expense if job is carried out, as hole repair can be accomplished along with the replacement job.
If you have an elderly relative who will need to have to use the garage, or are disabled and want area to put your wheelchair in your automobile, a double garage door will make this considerably simpler than two separate single doors which can restrict the amount of space you have to access the garage and your car.