Issues during construction

This page covers processes for managing construction and any issues that may arise.

Construction programming

The contractor is responsible for programming the construction and for managing subtrades. It is usual for a contractor to provide a plan setting out:

  • start and finish dates – a programme may have a number of start and finish dates where it is staged, for example, a given number of units or one floor is remediated at a time before work on the next block or floor starts
  • critical points in the programme (for example, completion of removal of cladding so that testing of timber for rot can be done before timber removal starts).

The key to good planning by the contractor is:

  • sequencing tasks so that work is not held up because something else needs to be done and so that work does not have to be redone because something else was not completed on time
  • regularly reviewing the programme to identify:
    • potential roadblocks
    • where things have not gone to plan
    • additional work that needs to be incorporated
  • regular site staff meetings to keep all key personnel engaged.

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Communication

As with all projects, open lines of formal and informal communication between the owner, owner’s agent (designer, engineer or consultant), BCA and contractor is essential to the smooth running of the project.

An essential part of communication is:

  • regular site meetings
  • having a formal means of recording what has happened and will happen (site notes, variation orders and so on).

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On-site monitoring

As the removal of failed building elements or materials progresses, there must be a process in place to evaluate their condition and decide how to deal with what is found. This is particularly important where damage is extensive or the extent has not been clearly identified at the design stage. Monitoring is likely to be a requirement where there is likely to be future litigation regarding the cause, extent and cost of the remediation.

Once a damaged area of wall is opened up, it is recommended that it is inspected by an NZIBS Building Surveyor, engineer, clerk of works or designer (if qualified) to accurately assess and identify:

  • the timber that must be replaced
  • where internal linings need replacing
  • removal of internal fittings such as kitchens to allow access to carry out repairs
  • the causes of the damage.

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Dealing with the unforeseen

It is likely that there will be an element of unknown work with all remediation projects, which may require:

  • additional diagnosis to determine the extent of the problem uncovered and the development of a solution
  • redesign of a proposed solution where the original detailing cannot be applied to the specific conditions identified on site
  • a variation to the consent and/or to the contract to remedy faults that must be repaired.

This work will need to be progressively done as the contractor proceeds.

This monitoring is also necessary to identify and provide resolution of issues other than weathertightness that may only become evident during reconstruction work.

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Variations to the contract

During remediation work, there are likely to be variations to the contract issued by the contract administrator, typically resulting from:

  • damage being more extensive than expected
  • an unforeseen problem needing to be rectified (for example, where it is found that the lintels are undersized and have sagged or that concealed bolted connections are loose)
  • what is detailed can’t be built on site
  • the owner requests a change
  • allocation of costs to a provisional or prime cost sum allowed for in the contract.

All variations need to be:

  • in writing with copies to all parties
  • costed
  • discussed at site meetings
  • approved by the BCA where the variation requires an amendment to the consented documents – many BCAs have processes in place where variations can be agreed to or rejected on site, with as-built details and drawings being provided during and on completion of the works to form a record.

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Timber testing

The selection of the areas of framing from which samples for testing are to be taken should be done under the direction of an NZIBS Building Surveyor.

The testing of existing timber for rot, fungi and evidence of existing levels of treatment must be carried out immediately after the cladding is removed. If testing is not carried out immediately, the testing results may not be reliable.

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Dealing with mould and fungi

Mould and fungi can be found on any building material but are usually present where any material containing cellulose (timber, fibre-cement, kraft building paper or plasterboard) are wetted.

While many do not pose health risks, Stachybotrys atra or Stachybotrys chartarum and some other types of mould are toxic and allergenic. They have been identified in building sickness syndrome both for occupants and contractors working on the site.

Spores that can become lodged in our respiratory system are more likely to be released if mouldy materials have dried out. Air sampling may be necessary where it is considered likely that spores have been disturbed and have become airborne.

Specific requirements need to be included into the conditions of contract to cover the possibility that mould will be uncovered and how it is to be dealt with – usually by the inclusion of a sum to cover such work.

For buildings that will be undergoing temporary, targeted or partial cladding repairs where the owner is likely to remain in residence, it is important that the interior of the building is isolated from the possible health effects of toxic mould if present.

To minimise the risk to them, it needs to be specified in the contract documents that:

  • work should be undertaken from the outside if possible
  • where internal work is necessary, that work area must be isolated from the remainder of the dwelling.

See Remediation details: Mould for information about testing and removal.

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Expenditure of sums

Expenditure of sums allowed for in the contract documents should only be authorised by a variation order.

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Weather protection

It is important that ‘dry’ areas of the building remain weathertight during construction. Specifying the installation of temporary weather protection will speed repairs and provide adequate protection. Specific requirements need to be included in the conditions of contract.

Temporary collection of rainwater should be provided where the remediation involves the removal of roofing and spouting to minimise the risk of wetting of the remaining structure and materials and also new construction that has not been closed in.

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Care of existing property

Provisions for ensuring the existing building, its surroundings and adjacent properties are appropriately protected against damage during construction activities should be clearly defined within the contract, which will typically be the responsibility of the contractor. Specific requirements need to be included in the documents.

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Site conditions

Remediation projects are generally dealing with an existing building within developed surroundings with limited space to work in, which adds to the complexity of the project.

Specific site conditions that may need to be accommodated include:

  • limited availability of clear space around the building when scaffolding is required, which may take up most of a standard side yard (an added complication is where properties share a common wall but only one unit is being remediated)
  • limited space for storage of demolition materials or waste bin
  • limited space for delivery of and storage of new materials
  • limited storage space for elements that are being removed, refurbished and reinstalled
  • width and slope of driveways (possibly shared) servicing the property
  • turning spaces for delivery vehicles
  • available parking for site staff (particularly on inner city sites
  • toilet facilities unless facilities within the building are available
  • protected trees
  • proximity of adjacent buildings/boundaries.

Updated: 12 June 2017