Dual Occupancy Design on the Central Coast

Dual Occupancy homes are a great option allowing you to use your largest asset and potentially double it, allowing you to live the life you dream of sooner or allowing you to share your land with familiy members that you love. Good Architect really enjoy coming up with duplex designs that suite your needs. Together, we'll create a dual occupancy home design that is tailored to you. When considering dual occupancy, it is a good idea to make sure the cost is within your budget as well. We create boutique dual occupancies made especially for you.

What is the difference between a Dual Occupancy and A Duplex?

While these are generally the same thing two attached houses, there are some instances where you can build a detached dual occupancy which is a seperate house that is not attached. This is still a dual occupancy for council purposes during approval, afterwards a DA can be lodged to create separate torrens title houses and it becomes a freestanding house. A dual occupancy or duplex can also be one house on top of another, sometimes called a manor home. 

Can I build a dual occupancy on my site?

The following land zonings permit Low Density Residential: R1, R2, R3, R5, RU2, RU6, C3 and C4. 

This means that subject to council approval you could be able to create a dual occupancy on your site. You'll then need to comply with the DCP requirements for dual occupancies which can be found here. These dual occupancies can then be subdivided into torrens title land that is smaller than the minimim lot size if it is in a residential zone.

I highly recommend getting a free callback from a town planner which you can organise here.

In general here are the site constraints for dual occupancies:

Height: as per the details found in the LEP maps or Mecone mapping below (below Land Zoning highlighted in yellow) or if it is not on an LEP map 10m

Floor Space Ratio (FSR): 0.5:1. This means that the floor area cannot exceed half of the site.

Slope: Dual Occupancy is unlikely to be supported on a site with a slope of 25% or more. Note - a rough way to determine your slope is to go to your measure tool in your iphone and slide it over to slope, it will give you a rough idea of if the site meets the parameters, although a survey will be nessesary to check that it does.

Minimum Lot size: 

• 550m² for attached

• 700m² for detached

• 800m² for battleax sites

• 1000m² for slopes with less then 20% slope where entry is from parallel streets

• 1200m² for sites with 20-25% slope where entry is from parallel streets

Minimum Width for Complying Duplexes:

12m where there is rear lane access, 15m where there is not.

Soft Landscaping: 25% must be soft landscaping, planted with grass or trees and not be paved or concreted

Private Open Space (POA): 45m² with a minimum dimension of 4.5m

Solar Access: POAs of the proposal and neighbouring POA must receive a minimum 3 hours solar access on June 21 between 9am and 3pm

Parking: 3 bed or less: 1 carpark, 4 bed or more: 2 carparks

Deep Soil: 12.5%

Setbacks:

Front: the average of the two nearest properties or if there are none within 40: 4.5m. Setbacks to classified roads are 7.5m and roads where the road reserve is less then 6m wide: 6m

Side: up to 4.5m high—0.9m, and for more than 4.5m—0.9m plus one-quarter of the height of the building above 4.5m

Rear setback: 4.5m to another property or 3m to a road or reserve.

Garage: 5.5m or 7.5m to a clasified road

Corner allotments: 2m + allow for traffic sightlines

Note: there are different requirements for dual occupancies in RU2, RU6, C3 and C4 zones, for access to the DCP for Dual Occupancies click here.

Bushfire and Flooding

Check if you are prone to flooding or bushfire. If you are prone to flooding you will need to get a flood information certificate. If you are bushfire prone, you will need to get a bushfire report. Here is a guide to finding out if your site is subject to flooding. Here is a guide to find out if your site is prone to bushfires.

Can I create two Torrens Title lots for my Dual Occupancy?

On the Central Coast, so long as there are enough services for each lot and they meet the requirements below you may be able to create two Torrens title lots, through and application to Central Coast Council. 

4.1C   Exceptions to minimum lot sizes for dual occupancies

(1)  The objectives of this clause are as follows—

(a)  to provide opportunities for affordable housing in appropriate locations,

(b)  to encourage housing diversity without adversely affecting residential amenity.

(2)  This clause applies to land in the following zones—

(a)  Zone R1 General Residential,

(b)  Zone R2 Low Density Residential.

(3)  A single development consent may be granted for development on land to which this clause applies if the development application is for both of the following—

(a)  the erection of a dual occupancy,

(b)  the subdivision of the land into 2 lots that are both smaller than the minimum size shown on the Lot Size Map.

(4)  Development consent may also be granted to the subdivision of land to which this clause applies if—

(a)  a dual occupancy has been lawfully erected on the land, and

(b)  the subdivision will result in 2 lots that are both smaller than the minimum size shown on the Lot Size Map.

Dual Occupancies - the Approval Process

Here are the steps you will need to take to get approval to build a dual occupancy. There are two stages for the approval process: Development Application and Construction Certificate. Both need to be completed before building can start.

Part A - Pre-DA

Before lodging the DA it is a good idea to talk to council to see if what you are thinking of is viable or has any issues that need to be resolved. Good architect is a specialist in duplex designs so we will help you get what you need.

1. Get a survey. This means that you know where your boundaries are, what the level of everything is and where your existing building is located on the site. Council usually requires this to be submitted with the DA. This will also show the location of existing services so that you do not plan to build over a sewer main which can be expensive. Surveyors that we have found to be good in the past include: Clarke Dowdle & Associates and Intrax.

2. Contact council to get them to give you a call back to discuss what you can do on your property. Here is a link to the council form for a call back from their town planners.

3. Get a town planner on board, they have a lot of experience submitting projects to council and can often tell you if what you are submitting is likely to be approved or better yet if there is no chance it will be (not pursuing projects that are simply not viable can save you a lot of money). A town planner that used to work for council and will tell you the truth about your site is Tim Shelley who can be contacted on 0409306186 or tim@tsplanning.com.au. There are times when council will still do unexpected things and there is no guarantee in the approval process, Tim will let you know about any red flags though.

4. Get your architect to prepare drawings for a pre-DA meeting with council. Here is a link to council to book in a pre-DA meeting:

https://www.centralcoast.nsw.gov.au/plan-and-build/development-applications/pre-development-meetings

Part B - DA

After going to a pre-DA meeting with council and resolving any issues they bring up, its time to bring other consultants on board to create Development Application documents.

1. Update your architectural drawings with the advice from the pre-DA meeting.

2. Get a Geotech for the site. Council will want to see this and the structural engineers will need it to design the footings at a later stage. Geotech we have found to be good in the past include: Douglas Partners and 5QS.

3. Get a QS on board as council will want an estimate and you will want to make sure that you can afford to build it. Aplas are generally good quantity surveyors.

4. Get Stormwater drawings. Send the Architectural Set onto the stormwater engineer and they will provide you with stormwater drawings that look at the flow of water on the site and design the stormwater system. Stormwater engineers that we have worked with in the past include: Quantum and ADW Johnson.

5. Get landscape drawings from a landscape architect, Xeriscapes is a good local landscape architect.

6. Get a waste management plan done, we've used TTM Group in the past.

7. Get your town planner to write their Statement of Environmental Effects to be submitted with the DA, this outlines how the submission complies or varies the applicable planning laws.

8. Get the Architectural Drawings stamped by a BASIX consultant, they make sure that there is enough insulation, windows are thick enough and there is enough rainwater storage to create a sustainable dwelling. BASIX is required by the NSW government for all additions over $50,000. BASIX consultants we have worked with that have been good are: Credwell and Certified Energy.

9. Submit the DA to Council. Council may also request other consultants depending on the project and the zoning, for example they may request an arborist report if you are removing trees or you may need to get a bushfire report if you are in a bushfire zone. For bushfire advice and reports Clarke Dowdle & Associates is generally good. The pre-DA meeting will give you a good idea of what consultants need to be engaged, although council often requests other consultant reports after the DA is submitted as RFIs so it it important to keep this in mind as an additional expense during the DA process. Council may request an acoustic report if your site is near a busy road or other source of sound, Spectrum Acoustics is generally good. They may require a social impact statement for larger proposals, Aegis Consulting Group does a good job.

Part B - Apply for a CC

1. After council approves your DA they will provide you with conditions of consent. Go through these to get a better sense of what you need to provide for the DA. Some common conditions of consent for dual occupancies include: provide a concrete driveway and provide a concrete pedestrian path in front of the house. You'll need to get your structural engineer to draw this up or a separate civil engineer. It will also normally include contributions for each additional dwelling on the site, these are updated each year and are around $12,000 per dwelling at the moment, this will need to be paid before you can obtain your Construction Certificate.

2. Update the Architectural drawings with the DA conditions.

3. Send the updated Architectural drawings to a structural engineer and get them to design the structure. Structural engineers we've worked with in the past include: 5QS and Geotron.

4. Send the updated Architectural drawings to a civil engineer and get them to design the civil works. Civil engineers we've worked with in the past include: Quantum and ADW Johnson

5. Co-ordinate the structure into the Architectural drawings and provide a finer level of detail including wall types and concrete setout plans.

6. Get your stormwater engineer from the DA to update their drawings for CC after the structural and other engineering drawings have been coordinated into civil.

7. Fulfill any other conditions in the conditions of consent.

8. Engage a certifier, either council or a private certifier to approve the Construction Certificate. Its often a good idea to engage them at the start of the process to give you a checklist, although they will only assess it at the end.

Alternative - Complying Development: CDC

If your site meets all the requirements it may be possible to do a Complying Development (CDC). These requirements are very similar to the Central Coast Council requirements for dual occupancies. The main reason you would submit a DA/ CC instead if a CDC is if there was something in the site that meant it did not comply, common causes of this are the site being flood prone or bushfire prone, these can be checked on Council's Central Coast Online Mapping. A CDC basically combines the steps of a DA and CC into one process that takes a lot less time to get approved.

The above is the minimum required to start building and is fine if you are only building an envelope and plan to do the interior fitout yourself. If you intend to get the builder to do everything, it is best to get a detailed design done as it means that the builder can price everything accurately and there are less items with a builders margin.

Detailed Design/ Interior Design/ Tender Set

1. Select all the finishes you want in your dwellings, everything from tiles to paint. This means that the builder can price it accurately and you will not get stuck with a builders margin.

2. Get your architect to do detailed design drawings of everything that is not a typical detail and all wet areas. If you want window sills to be a particular way, get them drawn up. Anything you want to be brilliant - get them to draw up, anything that is a standard detail can be left out.

3. Get quotes in from a builder, look at what they are including and what they are excluding, for more information look at this article How to Select a Builder.

4. Select a builder and start building.

The consultants mentioned above have been good to work with in the past, we can't guarantee how your experience with them will go in the future though, it often depends on the person you are working with and what is happening with them as well. We have mentioned them only because our past experience with them has been positive, we cannot guarantee anyone else's will be.