Essential guide to coastal home building in the
Bay of Plenty
Here's What You Need To Know
Considering building a home within the Bay of Plenty coastal zone or near estuary waterways? Refer to this checklist for some of the unique challenges to keep in mind.
Or let us do the leg work for you with our Architecture + Build Service.
We will research and assess the site for you, point out any obstacles and potential cost implications and recommend the most efficient pathway to consent and construction.
And best of all … the service is FREE.
We can help with pre-purchase due diligence (no obligation) even if you are only contemplating a build project.
Email us or call for a chat and to arrange a FREE site assessment: (07) 575 5555
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1. Stormwater Management
Coastal areas can be prone to weather extremes, and sandy soils may not drain sufficiently quickly during heavy rainfall. Council provided stormwater catchments are no longer a given and managing water disbursement is essential to prevent flooding. Most projects will require a site-specific stormwater management system designed by an accredited environmental engineer taking into account the site coverage, contours, paved and grassed surfaces. In some instances, a series of interconnected soak holes will provide a suitable solution however, inground attenuation tanks with slow release are becoming more common. This needs to be considered and factored into your overall project budget.
2. Geotechnical
Coastal sites will require a Geotech Investigation Report from an approved council engineer outlining the condition and stability of the ground and to review the building area for construction. Coastal foundations need particular attention. The report will include recommendations for the type of foundation to address any liquefaction potential and recommendations for structural engineer’s design.
The City / District Plan will set out what is deemed permittable activity along with any restrictions around boundary setbacks, height, location and site coverage of proposed buildings. If the proposed design does not meet all the criteria, then resource consent will be required.
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3. Natural Hazards
Council modelling identifies hazard areas that are susceptible to coastal erosion, inundation (flooding from the sea or harbour) and stormwater flooding from rainfall. Scenarios include flood modelling of the likely impacts of a 1 % AEP intense rainfall event for both the present day and the year 2130, being flood prone. An independent flood risk assessment may be required to be undertaken to review the council modelling data and determine the effect of the proposed construction on overland flow paths. The flood risk assessment report will set out a minimum building platform level (FFL) and can be used to support resource consent (if required) and building consent applications.
Check the City / District Council maps whether the property is located in a Tsunami Evacuation Zone. Tsunami Maps will provide guidance on evacuation routes and meeting points.
4. Site Survey / Daylighting Survey
If not already undertaken, a site survey will be required. This will set out the boundaries and contours of the site along with the location of any onsite services and connections to council services. A title search will identify any easements through the property that could potentially impact the design of a new building on the site. Depending on the proposed building design and proximity to neighbouring properties, a daylighting survey may be required to check the building height in relation to boundary rules and the effects of any infringement on the neighbouring properties.
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5. Foundations / Earthworks / Retaining
Ground conditions will generally determine the type of foundations suitable for the site. All foundations are required to be Specific Engineer Designed. Sandy soils may require ground improvements including earthworks to excavate, remove and replace base material with imported fill and recompacted to form a suitable building foundation. Depending on the contours of the site, positioning the home to achieve the ideal finished floor level may require substantial earthworks and / or retaining to provide a level building platform. If raising the site to take in views is part of your brief you need to factor this into your overall budget. Additional site investigation, earthworks monitoring, and approval will be required from an approved Geotech Engineer prior to foundation work commencing.
6. Coastal Erosion
Check the District Plan maps for whether your site is within an identified coastal erosion area. If your site is identified in the District Plan maps as being within a coastal erosion area, you will need to apply for resource consent and limitations will apply to the size, capacity and type of building that can be constructed.
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7. Archaeological
Archaeological sites are common in coastal areas with 12% of all known archaeological sites in NZ located within 1000m of shorelines. Check the local council (Mapi) website or with Heritage New Zealand whether there is an archaeological site on or near the property. In some instances, an inspection by a qualified archaeologist may be required and an Archaeological authority recommended. If any items of archaeological significance are identified during excavation, the process to assess and remove them will require input from an Archaeologist Specialist.
8. Wind and Exposure
Coastal winds can be strong and unpredictable. All areas in NZ are allocated a ‘zone’ for wind - from Low to Extra High - depending on the level of exposure. Wind direction, speed and frequency will influence the building design including bracing requirements, roof and wall cladding selection, weathertightness detailing, building entry locations, window size and placement and provision of shelter for outdoor spaces.
9. Utilities
In most instances, supply of power and telecomms to the property boundary is a given. However, in cases where a property has been subdivided or is infill housing, there can be unexpected cost if there is insufficient capacity within the power network for a new connection. Check with the relevant network contractor for additional costs to upgrade or connect to the power network if applicable.
10. Water Supply
While most coastal sites will have access to council supplied water, summer drought conditions may mean water restrictions are imposed during the hottest times of year. You may like to consider installing a rainwater and / or greywater harvesting and storage system to provide non-potable water for garden and lawn use. Alternatively, and particularly if you are considering installing a pool, a bore and pump may be worth considering. If you are installing a pool and connecting to council supplied water, you will be required to install a backflow prevention device (RPZ) at the property.
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11. Energy Solutions
With the cost of generating and supplying electricity continuing to rise, more people are turning to solar power solutions for self-sufficiency and to help manage energy costs. Solar systems are a significant investment and in most cases battery storage is necessary to gain the most benefit. A well-designed system will take into account the number of people living in the property and the likely energy requirements for lighting, hot water, heating/cooling, appliances and EV charging. If you are installing a pool, then heating the pool to extend the swimming season is another consideration. While solar systems can be retrofitted, installing as part of the build project is cheaper and more efficient.
12. Insulation and Heating
Comfort is key and, particularly in coastal environments, a cool home is often more important than a warm one. Good design is critical that takes advantage of north facing winter sun for passive solar gain, with wide eaves to provide shade in summer when the sun is at its highest and most intense. Modern insulation along with thermally broken window joinery and glass contributes to creating a home that provides year-round comfort. Factoring in an energy-efficient heating and cooling system will ensure your home is warm in winter and cool in summer, without skyrocketing energy bills.
13. Outdoor living
Let’s face it, the point of owning a coastal property is to spend as much time enjoying the outdoors as the seasons will allow. Consider factoring one or two sheltered areas into your design with roof cover over at least one of them. If your property is beachfront, then consider privacy and security both at night and during the day. While features like shutters, sliding screens, retractable blinds and louvres require some ongoing maintenance, they can provide privacy and extend the use of outdoor spaces. Increase all-year-round useability by adding features like an outdoor fire, outdoor kitchen and cooking facilities, (i.e. BBQ / pizza oven), heating, lighting and built in seating. An outdoor shower is a must have for that post-swim wash off, preferably located near to a bathroom with external access. Coastal homes also require carefully considered flooring choices that are easy to clean and will tolerate sand being tracked inside.
14. Living with Nature
While coastal living is a dream come true for most people, living with the natural elements is not without its challenges. Wildlife, particularly seagulls, may seem intent on making your life difficult. A gable roof ridge is an attractive spot for seagulls to congregate and guano will quickly spoil the look of a dark roof. Wires and other deterrents may be necessary to stop birds from settling on the roof. Landscaping to suit coastal conditions is also a consideration. Seek advice on coastal planting particularly around dune areas where native planting can help stabilise soil and reduce erosion.
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15. Durability And Aesthetics
Coastal homes need to be both durable and attractive. Choosing materials that maintain their good looks and can withstand exposure to sea spray and harsh weather elements is critical for the longevity of your home. Exposed steel, such as structural beams, screens, flashings, railings and balustrades needs to be appropriately treated and coated. Harsh UV light will accelerate fading and, particularly with exterior materials, may require additional maintenance. Consider low maintenance cladding and a colour palette that is less susceptible to fading. If selecting materials that require periodic repainting or staining, you will need to consider access and factor in scaffolding costs as part of ongoing maintenance
There are numerous considerations with planning a coastal build. If you would like help mapping out next steps, enquire about our Architecture + Build Service and FREE site assessment. We will talk you through any obstacles or hazards, consents and costs, and recommend the most efficient way to build a coastal home that will last.
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We want you to benefit from our knowledge and experience from the outset.
Thorne Group’s wraparound service brings architects, designers and construction together from day one, so modifications happen while the design is easy to adjust, not once it is too late.
This expertise is backed by nearly 20 years of continuous improvement across urban, coastal and rural projects.
“That is the good thing about in-house experience; collectively there is 80+ years of knowledge just in-house, so we know what works and what does not.” — Aaron Thorne
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"My advice is get them involved early, Gavin and Aaron know how to work with your architect to fine tune those very important details saving you money and avoiding costs and changes later".
Rebecca Hick
