Maintenance: Foundations and Paths

foundations

In this chapter we explain the building terms in relation to foundations and paths. We also examine commonly encountered problems and preventative maintenance.

Legislation - Strata Titles Act

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Legislation - Community Titles Act

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Foundations are commonly constructed using concrete strips or slab & beam forms. Strip foundations are commonly found in older units; they often feature timber floors on joists and bearers.

The following pictures illustrate how the common concrete slab and beam foundation is constructed.

Raft Foundations:

Our thanks to toolboxes.flexiblelearning.net.au for the following information.

Slab footings consist of concrete beams and floors across the entire floor plan. Slabs are also referred to as slab floors, slab on ground or raft slabs.

The stiffened raft slab is the simplest and most commonly used slab construction available. The stiffened raft configuration can be used on all types of sites (except problem sites - Class P).

Stiffened raft slabs consist of:

  • 100 mm thick concrete slab
  • edge beams
  • internal beams
  • steel reinforcement.

The concrete is poured in one operation.

Common Problems

The following pictures illustrate many of the commonly found problems associated with foundations and paths.

The picture below shows cracks in the walls of a unit. The strip foundations have subsided following leakage from a storm water drain. The water has washed away the soil supporting the foundations.

The picture below shows cracks in the external brick walls of a unit. In this case the strip foundations have cracked adjacent to the sewer pipe which serves the toilet on the other side of the wall. The sewer pipe had cracked and leaked, consequently expanding the clay beneath the foundation. This heaving has finally cracked the concrete.

The picture below shows the cement render breaking away from the concrete foundations. This is the result of a common concrete path rubbing against the render. The path is not connected/dowelled to the foundations, and therefore moves up and down with the moisture level of the soil beneath.

In this case a gap between the path and foundations would help to prevent this problem.

This path has heaved, the result of underlying tree roots. In this case the damaged concrete is a trip hazard. The Corporation would be negligent if it failed repair/replace this concrete.

The wall below is suffering from efflorescence. The salts have appeared in the wall since the new concrete path has been poured. The path and wall should be isolated from each other with a vapour barrier. This will stop transmission of water bourne salts.

The soil adjacent to this path has been allowed to dry out. This had resulted in the path moving away from the building as well as sinking. Cracking has occurred around the pipe work in the path. Sever cases can result in pipes being damaged.

The common path below has no structural problems, however, it is occupied by the owner's hot water services. This renders the path difficult to use. The path also serves the common clotheslines.

Tools

The following tools may assist in the maintenance of foundations & paths.

CSIRO foundation maintenance tips

Caring for concrete

maintaining concrete

Preventing structural damage

foundations care

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