Old, detached garages are notorious for undergoing a little shimmy, rock and roll over the years. Often the original foundation or footing doesn’t properly resist frost or soil settlement, so this movement is just inherent in the construction. At times the framing is marginal – just enough to get by but not built for longevity. What should you do with your old, leaning garage?
In most cases, just ignore the movement if it’s small– say, a 1-inch tip per 6 feet vertical. But if movement interferes with the garage door operation or other doors or windows, you may want to consult a carpenter. If movement is ongoing, you definitely must address it.
In the worst case, you can place a new foundation under the framing. This involves lifting the garage and replacing the concrete foundation, which is an expensive operation. In most cases, the carpenter can simply brace the structure to prevent further movement. With a little more effort, you can jack or pull the structure close to plumb and then install bracing.
With any old structure, the key is keeping a weather-tight roof and directing surface water or rainwater away from the structure. Water, frost, and frozen water can severely damage the foundation and structure.