What You Need To Know About Underpinning in Melbourne
Underpinning in Melbourne is a technique used to strengthen and stabilize an existing foundation when refurbishing or converting a building.
Read on to find out the foundation problems that can be fixed by underpinning and the process involved.
Applications of Underpinning
Underpinning is used to:
- Stabilize a foundation that has settled
- Stabilized foundation movement due to an unstable slope or landslip
- Stabilize a foundation supported on an unconsolidated ground
- Stabilized a foundation affected by excavation or mine work
- Stabilized a foundation weakened by soil erosion
- Stabilized a foundation affected by heave or subsidence
- Stabilized a foundation damaged by vibrations
- Accommodate an additional story, sewer, or a newly built structure next to the existing building
- Strengthen a foundation due to increased load
How to Determine the Need for Underpinning
It’s necessary to hire the services of a qualified structural engineer or surveyor to inspect the foundation and identify the causes of any structural problems before starting an underpinning project. Underpinning is only needed when a building shows signs of structural and foundation damage. The engineer’s report will recommend the best underpinning method to fix the structural issues.
What to Consider Before Underpinning
- Preliminary assessment is done to determine the extent of the damage
- The cause of structural damage is determined using a monitoring technique. It may take several months to get valuable data.
- It’s necessary to determine whether the foundation movement can be resolved immediately to stabilize the structure.
- Further investigation is necessary to determine the depth and size of the affected foundation and the soil conditions. The investigation is typically done by a qualified ground investigation contractor. Sometimes, the investigation contractor may work with a builder.
- If the engineer recommends partial underpinning, an underpinning expert should ensure that there won’t be any differential movement existing between the untreated and treated areas.
- In case underpinning is required near another building or next to an adjacent building, there should be a legal agreement between yourself and the owner of the adjacent building.
- If underpinning is necessary, there may be other structural repairs to be done.
What Does Underpinning Involve?
Underpinning entails widening an existing foundation and/or increasing its depth to transfer its weight to a stable soil. There are several techniques used in underpinning. Mass concrete method, also known as traditional underpinning, is the most widely used underpinning technique.
Mass concrete involves excavating beneath and/or around an existing foundation in several controlled stages up to the depth at which a stable soil exists.
Thereafter, concrete is poured into the excavation. Once it cures, another underpin is excavated and concrete is poured. The process continues until all the required underpins are installed.