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INFILL HOUSING PROCESS

Did you know you don't need to Sub-divide or Cross Lease to build another house on your large property? With the recent introduction of Medium Density Residential Standards the rules around multiple homes on one plot of land have been largely removed and building on an already large site is now easy to achieve. There are some hoops to jump through similar to a sub-division as local councils manage infrastructure, climate change and stability issues but like a sub-division generally these are more about assuring your proposal is viable with the available information than trying to prevent development. Unlike a sub-division the ability to sell the additional household is limited which appears to be favourable. 

There are some real benefits to building a new additional dwelling on a large property, namely:

  • A home and income situation can add value to your land,

  • You save a lot of money from the sub-division process,

  • It is a cheaper and easier means to provide accommodation for family or friends. 

  • If you love where you live but don't wish to live in your same house with your large garden sub-dividing can enable a smaller house and garden without moving neighbourhoods and without the cost of land. 

If you are interested in undertaking a new infill house the first step is to make a call, send us an email or contact us through the details at the bottom of the page, all projects begin with clients reaching out to us via referral or after some initial research online. 

Our first step is to meet you and have a look over the proposed site. This has no cost associated, it merely allows us to introduce ourselves and meet you initially. 

The rest of the process is reasonably straight forward, but it does involve a lot of co-ordination and oversight, the flow of an infill project we are involved with will follow roughly the process below. 

PRE-DESIGN

Pre-Design for infill housing is the first real phase of the project and it is quite heavy in exploratory functions. 

Initially we will co-ordinate with a group of other consultants with sub-division experience such as:

  • Surveyor: for Topography surveying with 3D digital files we can use,

  • Planning Consultant: for Town planning advisory and consultancy,

  • Plumber / Drainlayer: for CCTV inspection of nearby drains,

  • Geotechical Engineer: For advice on ground stability and suitability. 

Once the topography information is provided, we discuss the planning constraints with the Planning Advisor and Civil Engineer to establish the limits and restrictions of the proposed site from a council perspective. 

Once this stage is completed as our designers, we will have enough information to discuss the extent of the development proposed and a thorough understanding of the likely sub-division or cross lease costs will be known. This enables us to form and agree to brief and scope of works with you as the client and developer. 

Costs:

Expect to spend in the vicinity of $6,000+gst across all of the consultants to obtain all that is required to commence the project. 

 

Timeframe:

Typically, it can take up to 6 weeks with the availability of the Surveyor usually the longest lead time. 

DESIGN STAGES

CONCEPT DESIGN

The concept design phase of work transfers the information gathered during the Pre-Design Phase to a drawn form studying high level matters such as building bulk, location, form, early building planning consideration etc.

This phase is primarily concerned with forming shapes and inter-spatial relationships but we do offer a glimpse into materials and potential colours*. 

Co-ordination is required between ourselves as the principal designers and:

  • Planning Consultant: for affirmation of bulk and location compliance,

  • Landscape / Urban designer: for Preliminary design of any streetscape to meet the planting and street frontage requirements within the Local Authorities urban design guides. 

  • Specialist consultants for any specific requirements such as Passive House, Homestar, Greenstar, Lifemark etc. 

You can expect to see some generic perspective 3D views and floor plans of a loose nature throughout this stage whilst we work towards meeting your brief and ensuring the new house is feasible. 

Costs:

These will vary depending on the size of the project, for a typical infill house on a flat section expect to spend in the vicinity of $8,000+gst across all of the consultants to obtain all that is required to design the project to the end of Concept Design.

Timeframe:

Typically, it can take up to 6 weeks for this phase with the vast majority of the time being the design process itself, testing and exploring options. Engagement with clients is important throughout this process and therefore time is required to digest and understand the design and design updates before confirming the design to proceed to the next stage. 

DEVELOPED DESIGN

The Developed Design phase further develops the approved concept design to coordinate between separate building consultants and to incorporate any matters resulting from a town planning or cost estimate process.

We prepare the vast majority of the structural drawings and sub-contractor documentation during this phase and therefore it is the largest phase of the project from an architectural perspective. 

On completion of Developed Design the following consultants become involved in the project:

  • Structural Engineer: Specific design of foundations and elements outside the scope of generic standards

  • Geotechical Engineer: Working alongside the Structural Engineer on foundation design

  • Home system experts for Space Heating, Water Heating, Solar Energy provisions, Electricity Storage provisions, Home Automation, Centralised Vacuum systems 

  • Landscape / Urban designer: Final design of the landscaping aspects of the project. 

  • Planning Consultant: for Assessment of Environmental Effects reporting and submission of Resource Consents to Local and Regional councils,

  • Civil Engineer: to prepare supporting information for the services installation if required. 

  • Other Specialist consultants introduced during the design phase will prepare final reporting as required. 

  • Quantity Surveyor or agreed contractor: For indicative pricing. 

  • Finishing consultants such as Lighting Designers, Colour Consultants, Interior Designers etc. 

Completed developed design drawings are sufficient for use alongside an Assessment of Effects, Landscape Plan and Civil services design to obtain planning permission for the project if resource consent is required (often it isn't). 

Most quantity surveyors will offer a check measure service at this stage for a low fee if a preliminary cost estimate has been obtained prior. This is a valuable budget check prior to submitting the documents to tender or council. 

Costs:

These again will vary depending on the size of the project, for a typical infill house on a flat section expect to spend in the vicinity of $25,000+gst across all of the consultants to obtain all that is required to design the project to this point.

Council Fees will play a big part in the financials at this stage as well with potential for Resource Consent fees and definately Development Contribution fees. As of Dec 2022 in Wellington City Development Contribution fees total for a single additional dwelling will be in the vicinity of $8,000incl GST. 

Timeframe:

Typically, it can take up to 8-10 weeks for this phase with the time spent equally between ourselves and the consultants.  

BUILD COST ESTIMATE

For budget sensitive projects in the current environment it is not possible to estimate the build cost based on recent or historical pricing. Therefore the only opportunity to accurately gauge the cost of the build is to engage a Quantity Surveyor to provide preliminary cost feedback at the completion of Concept Design and Developed Design. 

The fees for this service are in addition to our own but are a condition of us taking on work where a budget is fixed. 

DOCUMENTATION STAGES

RESOURCE CONSENT

Resource Consent may be required if the proposal infringes one of the bulk and location rules for the site. Often it is not until the completion of Developed Design until the full scope of the planning permission is known as technical elements such as earthworks volumes or exact structural heights are unknown to that point. 

Working with the planning consultant early usually removes any surprises here, however from time to time we find a breach as a result of engineering or civil design not quite lining up as expected as we address the needs in the assessment of effects as they arise. 

On occasion the affects may be considered to be adverse to a neighbour and as such a neighbour may be required to sign an affected parties form. Presenting and discussing the affects with neighbours is often the client responsibility, with the support of ourselves and the planning consultant.

 

Should the neighbours not agree then the process becomes slightly more complicated, time consuming and the viability of the proposal will require re-visiting. 

DETAILED DESIGN

The Detailed Design phase builds on the Developed Design and is the process of finishing a set of drawings, specifications and schedules to allow a building consent to be applied for and the formal pricing process of the building works to commence.

We utilise the latest software solutions to ensure our documentation is of the highest quality and accuracy. Quality documentation is the no.1 priority at HWA and one of the key reasons we get referred work. 

Great documentation = less changes and lower on-site costs. 

To complete the project we work in with the following consultants:

  • Structural Engineer: Specific design of foundations and elements outside the scope of generic standards

  • Home system experts for Space Heating, Water Heating, Solar Energy provisions, Electricity Storage provisions, Home Automation, Centralised Vacuum systems, Balustrading installers,  

  • Other Specialist consultants introduced during the design phase will prepare final reporting as required. 

  • Frame and Truss designers

  • Finishing consultants such as Lighting Designers, Colour Consultants, Interior Designers etc. 

Costs:

These again will vary depending on the size of the project, using our typical infill house on a flat section expect to spend in the vicinity of $15,000+gst across all of the consultants to obtain all that is required to complete the documentation for the project to gain approval and to be tendered and built from.

Council Fees will be required at this stage as well with Building Consent fees and Curb deposit fees. As of Dec 2022 in Wellington the council fees total for a dwelling around $800k in value will be in the vicinity of $10,000incl GST. 

Timeframe:

Typically, it can take up to 6-8 weeks for this phase with the time spent equally between ourselves and the consultants.  

Council time frames are generally 6 weeks from the time the consent is accepted in for processing and the council fee is paid. 

DELIVERY

PROCUREMENT^

Procurement is the process of preparing tender documents or preferred contractor documentation that along with the approved Detailed Design documents, can be offered for contract pricing.

 

At the conclusion of this phase a building contract can be prepared for execution between the you and your contractor. 

OBSERVATION / ADMINISTRATION^

Contract Observation or Administration runs in parallel with construction to the completion of all built works.

 

Our role in Observation is just that. To observe construction and determine that the completed work is generally in accordance with our documents. Our observation is limited to our scope of works and inspections will be required by:

  • Structural Engineer: for oversight of the specific design elements they are responsible for, 

  • Civil Engineer: for oversight of specific design elements they are responsible for,

  • Local Authorities also have a set of inspections required for each building in their territory. 

Our role in Administration if required is to manage the administration of the building contract and to observe construction to determine that the completed work is generally in accordance with our documents.

Clients often choose to administer their own contract in conjunction with their builder and engage us to ensure the works are in accordance with our documentation. 

THINGS TO BE WARY OF

Here's a few of the things we find cause the most challenges with in-fill housing proposals:

Infrastructure:

  • Council infrastructure for three waters in most areas is massively under prepared. Provisions for on-site water storage during high rain events is required now more often than not.

  • Proximity to public drains is no longer managed as it once was and must be avoided now. This removes a large tract of available land in areas where pipes run below ground within private property. 

  • Flooding is a recent addition to the council list of concerns. Overland flow and potential flooding areas need to consider what affect the proposals can have on neighboring properties. We've found the methodology applied and application of the data to be quite challenging to work reasonably within. 

  • Development contribution costs, which are fees charged by councils to cover additional infrastructure required per household. These fees are often unrealistically high and often ignore the realisation that each site now has a cost associated with mitigating pressure on council infrastructure and rates are charged annually to use and maintain the same infrastructure. 

Climate Change:

  • Whether a sceptic or not Local Authorities have largely brought into the idea so it features heavily in their plans. 

  • Aspects such as storm surge, coastline vulnerability, sea level rise and storm wind speeds are all part of mitigating the potential for future damage as a result of climate change. It's next to impossible to change a Local Authorities perspective on these affects. 

Ground Stability:

  • Liquifaction reporting is becoming a common requirement throughout New Zealand at the moment. Testing is expensive if it is required by the council. Over $6k +gst as of Dec 2022. 

  • Slope stability is an issue in hilly areas with landslips a plenty happening during heavy rain events. 

Airport / Road / Port Noise restrictions:

  • As resource management evolves areas subject to disrupting noise such as roads, airports and sea ports (we're sure stadiums and race track provisions will come) there are requirements for fresh air and sound deadening construction to be considered. 

House size restrictions:

  • In some areas the size of a second dwelling is restricted, whether it be by height, floor area or proximity to the existing. For example in many Rural areas a secondary house is often restricted to a 60m² minor residential unit. 

*   = Colour selection is a consultant cost outside the scope of HWA. Colours explored in the design stage are to be considered in the            context of architectural presentation only. 

 

^ = We strongly encourage the inclusion of these phases based on experience however these two phases are optional in the scope of

       services.

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