A sinking foundation can be lifted, most often by installing piers to re-level and support the weight of the house. Depending on the cause and extent of the sinking, other methods to lift a foundation include underpinning and mudjacking. Consult a foundation repair pro to determine the best way to lift your sinking foundation. 

A good slump height really depends on the project, but there is a use for nearly all slump levels. For example, low slumps are best in projects that require structure, such as curbs and roads. High slumps often require additional reinforcement, but they flow more freely into hard-to-reach spaces.

On average, a mudjacking repair lasts between five and 10 years, though it can sometimes last for well beyond a decade under ideal conditions. Its longevity depends heavily on several factors, including the condition of the underlying soil, environmental conditions like freeze/thaw cycles and erosion, and whether the root cause of the sinking, such as drainage issues, is resolved. Because it doesn't always fix the underlying problem of loose soil, mudjacking is often considered a temporary solution. Proper maintenance and evaluation can help extend its lifespan.

There is no real alternative to underpinning, although mudjacking and polyjacking are other repair methods that can add support from underneath your foundation. Rather than placing supportive piers under your structure, these involve pumping a material under your slab to lift a sunken section back into its original position. Polyjacking, in particular, is sometimes a suitable solution for stabilization issues under slab foundations, but underpinning is often accepted as the best and most permanent solution.