Design FAQs

See below for a list of frequently asked quesitons.
If you have one not covered below feel free to contact us.

I am doing alterations to an existing building. Do we need to upgrade the whole building due to earthquake prone issues?

After the Christchurch earthquakes, councils tightened up the seismic requirements for buildings. This affects multi-storey buildings in Auckland and many are required to review and upgrade their seismic performance, often driven by insurance company requirements.

There is a provision under the Building Act especially for ‘Change of Use’, that sets the requirement for increasing the standards of seismic performance of the building.

If you are proposing ‘Change of Use’ alteration to the building, the issues of seismic upgrade of the base building must be dealt with more carefully as it may involve works outside your tenancies.

The extent of upgrade works, if any are required, would need early discussion with Council and your consultant.

If the proposed works are ‘Alteration to Existing’ building, there is no Building Act requirement to increase the seismic performance of the building. Sometimes, however, Council may still require some upgrades of the base building if they consider the building is ‘dangerous’, being earthquake prone or by other local council’s policy.

What are the building compliance implications for a Commercial racking installation?

THE DESIGNFIRE has worked on a number of racking installation projects for commercial racking companies. For these projects we are able to provide complete architectural and fire engineering packages or standalone fire engineering services.

A building consent is required for high stud commercial storage racking installations in both brand-new buildings as well as existing warehouse buildings. This is because of the following issues:

The high stud racking can exert a lot of weight on the floor, especially with the stored contents. This is particularly important to check if the floor is a suspended floor or involves upper floors. The positioning of supports and concrete thickness are to be carefully checked by a structural engineer. Not all structural engineers can manage the design of racking systems as they require specialist software to calculate the loadings. THE DESIGNFIRE works closely with reputable structural engineers who specialise racking design.

The racking layout design may also affect the original fire engineering design criteria, especially with egress distance.

Sometimes the original building has not been designed as a high fire load warehouse, which was acceptable before 2010. The term ‘capable storage height’ was introduced after 2010. The application may then be considered as “Change of Use” under the NZ Building Code and may require more extensive assessment.

According to the Building Code, even when the works relate to only part of the building area, the whole building needs to be reviewed for compliance on the ‘as nearly as is reasonably practicable’ (ANARP) basis.

It is tricky to assess the ‘right quantity of improvement’ on an ANARP basis as it requires a full depth of understanding on how building compliance works in terms of the actual requirement and how it applies in real-world (i.e. how the council would apply).

On projects involving racking installation, THE DESIGNFIRE plays a unique consulting role few other consultants can match due to our combined expertise in building compliance, fire engineering as well as architectural designing. Our consulting ability especially shines in the case of assessing older buildings and warehouse testing to comply ANARP.

What are the building compliance implications of a residential conversion to existing multi-storey apartments?

Having successfully completed a handful of apartment conversions projects, THE DESIGNFIRE team has expert knowledge into the compliance implications of these projects.

We are always happy to discuss these projects with you, and can offer a summary of the relevant section of the Building Act 2004.

Section 115 of the Building Act states:

“115 Code compliance requirements: change of use

An owner of a building must not change the use of the building,

(1) In a case where the change involves the incorporation in the building of 1 or more household units where household units did not exist before unless the territorial authority gives the owner written notice that the territorial authority is satisfied, on reasonable grounds, that the building, in its new use, will complyas nearly as reasonably practicable…”

Usually, Change of Use requires attention only to structural, fire and accessibility compliance. However, in creating a new dwelling, you are required to comply with all aspects of the Building Code requirements on an ‘as reasonably as practicable’ basis.

The main compliance requirements for such a conversion include:

  1. Acoustic compliance – the apartment unit would require better acoustic insulation both for residing comfort but also as specified by the Building Code. The acoustic performance is measured by ‘STC’ rating. Generally, apartments must achieve an STC rating of no less than 55.

As part of the conversion works, an acoustic engineer is to be engaged to provide acoustic solutions.

  1. Fire compliance – many of high-rise buildings in Auckland CBD were built in the 1980s, which poses some concern for developing them into residential units. In the 1980s sprinkler systems were not mandatory in high-rise buildings, yet they are now a mandatory requirement.

Where the sprinklers are installed in a newer high-rise building, the compliance implication and justification are made simpler.

In both cases, a competent fire consultant will need to review the overall building fire system and make a case (or justify) for any shortfall of compliance for the conversion. A fire consultant needs to determine the level of upgrade strategy based on cost, sacrifice and compliance benefit and occupant safety.

  1. Acoustic and Fire compliance – often one construction system needs to meet both compliance criteria and the system will need to be carefully studied and selected to ensure compliance for both requirements.
  2. Other requirements –other building code requirements that require consideration are:
  3. Energy efficiency – insulation performance of the unit – residential unit requirements are more stringent.
  4. Accessibility – whether the unit is for long term or short-term accommodation.; often the main stairs are not Accessible stairs that may require justification.

 

Do we need to review the whole building when doing building works in only one unit of a large complex?

When considering building works and compliance in a multi-unit situation of an existing building, often the unit owners only consider the fire engineering implication of their own unit. This can cause delays in the council’s building and compliance assessment process.

The Building Act requires that “Buildings” must upgrade over time to keep up with increasing compliance and regulation requirements in NZ. Very often, “Building” refers to the overall complex.

Therefore, sometimes you will need to review the whole building even if you are only doing the works in one area. Whether the whole building will need to be reviewed or not depends on the following factors:

  • Age of the building
  • Significance of the proposal (amount of fit-out works and the area it occupies of the overall “Building” area)
  • Whether the proposal involves Change of Use or not
  • Whether the proposal involves Sleeping usage or not

The fire consultants will need to go through the history of the building and calculate whether the whole building assessment will be required or not.

This whole building assessment is subject to the ‘as nearly as is reasonably practicable’ (ANARP) test, under section 112 of the Building Act. This means that, depending on the scale and significance of the proposal, the base building non-compliance issues can be considered as ‘complying’ on ‘as nearly as is reasonably practicable’ basis.

This assessment is called ‘Gap Analysis’ in technical terms and sometimes a fire consultant will need to go through this analysis in the fire report. Where ANARP analysis is performed, a fire consultant must justify the situations and provide suitable explanation to council to get the approval to proceed the works.

Do we need to conduct a base building review for Council if we’re changing the use of our commercial space?

For this type of change, it is always advisable to consult a professional design team that is experienced in working with Council, such as the team at THE DESIGNFIRE.

This is because the interpretation of change of use isn’t always as straight forward as you might think.

According to MBIE, a change of use occurs when both:

  • the use of a building or part of a building changes from one use to another as defined in the Building (Specified Systems, Change the Use, and Earthquake-prone Buildings) Regulations 2005 (the Regulations)
  • and the new use has more onerousor additional Building Code requirements than the old use.

Source: https://www.building.govt.nz/managing-buildings/change-of-use-and-alterations/

We need to understand the defined term of the building’s ‘use:

The ‘use’ of every building or part of a building is categorised by law. For the purposes of the Building Act, that use is specified in Schedule 2 of the Regulations.

The key issue here is that simply changing the ‘use’ is not automatically considered as ‘Change of Use’ as defined as section 115, which would trigger some base building upgrades on the ‘as nearly as is reasonably practicable’ (ANARP) basis.

We recently came across this during a design fit-out where a space that was previously used for retail was going to be converted to a bakery. The business was, in essence, changing from selling goods to foods. But the change wasn’t as clear cut as that, and there was some confusion over whether there was a technical change of use. You can read the full story here in our blog.

If not determined correctly, the change could end up costing a business unnecessary expense and down time. It is always best to seek guidance from a team experienced in building code compliance. Feel free to get in touch with us if you need any clarity on this.

What are the building compliance implications of a boarding house conversion?

If you’re considering opening your house up to boarders – for example, taking in overseas students – there are things you need to consider which determine whether the conversion involves any building or fire compliance requirements.

First and foremost, the Building Act stipulates different Purpose Groups and Risk Groups based on the number of people in the house and how they live together (i.e. as one family-type environment or as independent renters in separate rooms). How the building is occupied then helps determine whether the building is considered a household unit or not, which in turn, determines what type of Fire Compliance Document may be needed.

In short, this is not a simple scenario to assess as the Purpose Groups and Risk Groups of the Building Act are quite complex. For an example we’ve worked on, you can read the full story here in our blog.

If you have a specific conversion in mind, please get in touch with us for more clarification.

 

Please have a read of our blog stories for relevant case studies.

When building a residential home, how much should we budget for earthworks?

It’s common to come across clients developing and budgeting for a residential property who haven’t also taken into account the costs of earthworks needed for their project. One of the first things they try to determine is the estimated square meter cost for building the residential home, but builders typically exclude the costs of earthworks or site works in their pricing, making it difficult to verify the actual cost of the build.

While site works can be hard to quantify at the time of planning, we can provide some  guidance in estimating these costs (accurate as of 2020):

Excavation and exporting soil

On average, an earthworks truck can take 6m³, at a cost of around $500 per truck.

However, it is wise to double the soil volume when calculating how many truckloads you’ll need. That is because soil is not compacted on the truck as it is while in the ground. For example, if the total excavation volume is 6m³, it will take more than one 6m³ truck load because of the fact that the soil is not compacted on the truck. It would be safe to estimate two loads in this instance. So, if you have 60m³ of soil to be exported, you can expect to need 20 truckloads.

A standard team can usually manage 10 truckloads per day, depending on site access.

In addition, a digger/excavator will cost approximately $1000 to $1300 per day.

Hardfill import

On average, a single truckload of hardfill will cost around $400 (approximately $80 per m³).

Truck charges are usually $120-150 per hour, or around $1000 per day.

In addition, a digger/excavator will cost approximately $1000 to $1300 per day.

Note

Please note that excavation, earthworks, site works costs will vary for each site depending on its conditions and access.

The above figures are a rough estimate, accurate at the time of writing, and are only to be used for reference purposes only.

 

Please have a read of our blog stories for relevant case studies.

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