Jacking up — Dutch *opvijzelen* — is raising a complete building or structural element with hydraulic jacks, usually so that something can be installed underneath: a new foundation, additional height, or transport equipment to move the building.
It sounds spectacular, but it is a proven technique. As long as the load is picked up evenly and the building moves as a whole, hardly any cracking occurs — precisely because the structure does not deform, it simply rises.
What it is used for
- Foundation repair. Where timber piles have decayed or settlement has occurred, the building is raised so new piles or a new foundation can be installed beneath it.
- Correcting subsidence. In peat areas the surrounding ground sinks; a pile-founded house stays put while an extension or the ground level drops. Jacking the settled part restores the level.
- Raising against flooding. In vulnerable locations a dwelling is sometimes permanently set higher.
- Relocating historic buildings. For infrastructure projects, whole buildings are jacked up, placed on rails or transport dollies and moved.
- Gaining space. Turning a low crawl space into a full basement storey.
How it is done
- Investigation. Structural survey, ground investigation and a record of existing cracks and out-of-plumb, including photographs and monitoring points.
- Establish the load path. A steel yoke or grillage of beams is installed under or through the masonry, so the weight can be picked up at a limited number of points.
- Position the jacks. Hydraulic jacks on a stable reaction point — usually new piles or temporary support.
- Lift evenly. All jacks are controlled centrally, often by computer, lifting in steps of a few millimetres at a time.
- Monitor. Level, tilt and crack width are measured continuously throughout.
- Underbuild. Once the target level is reached, the permanent structure is built underneath and the jacks are released.
Points to watch
- Connections break. Drainage, water, gas and electricity connections are fixed in the ground and do not rise with the building. They must be disconnected in advance and reconnected at the new level.
- The neighbours. In a terrace you are tied to the party wall. Jacking a single house in a terrace is far more complex than a detached building and virtually always requires agreement and legal arrangements.
- Not a DIY job. Use a specialist contractor, with a structural engineer who has calculated the load path.
- Consents. Raising a house changes its height and datum level; check the local plan and expect to need planning permission.
Related terms
- Foundation repair
- Driven pile
- Pile extension piece
- Wood rot
- Structural engineer
Learn more about building terms in our knowledge base at fredsdiyplans.com.