An engineer will need to verify that the garage's existing framing and foundation can bear the weight of an addition. Garage walls often have exposed framing, says Tiplady, but if yours are finished, you'll need to cut away the drywall to see what's behind it. In Barrington, Tiplady installed a larger header above the garage door to help carry the load of the rooms above, and put in a support beam for the addition's floor joists.
For the foundation, a contractor will need to dig several holes to check its depth and condition along the garage's perimeter; if the foundation is inadequate, he'll need to bolster it or put in a new one, both of which are complex, pricey jobs. Fortunately, Geoff and Michelle's foundation beneath the garage's back and side walls was sufficient. A new footing was added on the street side of the house, however, to accommodate other structural changes during the remodel.
Shown: The attached garage (BEFORE) was added on several years after the house was completed. Above it, the architect and contractor designed and built an addition that accommodates a bedroom and a small portion of a new bath's footprint. The entire house got a curb-appeal boost from new cedar-shingle siding and details such as fascia boards and trim, which help the new space look properly scaled and connected to the older structure.