Ask the Builder – Free House Plan: Modern 4 Bedroom Duplex Design | Plan 190 DU

Looking for an affordable way to build two homes under one roof?

This week’s Ask the Builder – Free House Plan is our Plan 190 DU, a practical 4-bedroom duplex design created for families, investors, multi-generational living and anyone considering building one property with two separate residences.

With 2 bedrooms in each unit, separate entrances, individual garages, kitchens, bathrooms and living areas, this compact duplex makes excellent use of the available floor area while maintaining privacy between the two homes.

FREE HOUSE PLAN – PLAN 190 DU

Download the Free Plan

Modern 4 Bedroom Duplex | 2 Bedrooms Per Unit | 186.68 m² / 1,942 sq. ft.

Plan 190 DU provides two self-contained homes within one building.

Each side has been designed as an independent residence, making the plan suitable for a range of building and investment strategies.

House Plan Features

• 4 Bedrooms Total – 2 Bedrooms Per Unit
• 2 Separate Living Areas
• 2 Kitchens
• 2 Meals Areas
• 2 Bathrooms
• Separate WC Areas
• 2 Laundries
• 2 Garages
• Separate Entrances
• Built-in Robes
• Practical Single-Storey Design
• Modern Duplex / Dual Living Layout

Building Size

Total Building Area: 186.68 m² / 1,942 sq. ft.
Overall Width: 20.33 m / 66' 8"
Overall Length: 9.61 m / 31' 10"

The relatively shallow building depth can make this an interesting option for wider residential blocks where a conventional deep duplex design may not be suitable.

Why Build a Duplex?

A well-designed duplex can provide considerably more flexibility than a conventional single-family home.

You could live in one side and rent the other, accommodate parents or adult children nearby while retaining privacy, build for two related families, or use both residences as investment properties.

For investors, the attraction is straightforward: one building can provide two separate rental residences.

For families, it can offer something equally valuable—living close together without everyone having to live in the same house.

Ask the Builder: Is a Duplex Cheaper Than Building Two Separate Houses?

Potentially, yes.

One of the advantages of a duplex is that the two residences form part of the same building. Depending on the design, site and local building requirements, there can be opportunities to reduce duplication compared with constructing two completely separate houses.

However, the land, planning requirements, services, engineering, approvals and local construction costs all need to be considered before deciding whether a duplex is the right option for your property.

This is why I recommend getting the design in front of builders early and obtaining realistic pricing before committing to the full construction documentation.

Use the Free Plan to Start Your Research

The purpose of our Free House Plan series is to give homeowners and investors a genuine design they can use when exploring a building project.

You can study the layout, compare it with your land, discuss the concept with builders and start getting an understanding of what a similar duplex could cost to build in your area.

It is a much better starting point than trying to explain your ideas without a floor plan.

Important – This Is a Concept Design

This free house plan is provided as a concept design and planning resource.

It is not a permit-ready or construction-ready set of drawings.

Before construction, the design may need to be modified to suit your particular property and local requirements. Depending on your location, this may include planning approval, building approval, structural engineering, energy requirements, soil conditions, site levels and other local regulations.

Always check the requirements with your local building professional or approval authority before proceeding with construction.

Want to Change the Duplex Design?

You don't have to build the design exactly as shown.

If you like the general layout but want to make changes, we can customise the design to better suit your property and requirements.

You can simply send us your notes, marked-up floor plan or even a hand-drawn sketch showing what you would like changed.

Changes could include different bedroom sizes, larger living areas, alternative kitchens, additional bathrooms, different garages, revised façades or other modifications.

Upgrade to Full Construction Plans

If you decide that Plan 190 DU is suitable for your project, ask us about upgrading the concept to a full construction-plan package.

The final documentation can then be developed around the design and your project requirements.

Local engineering, approvals and other site-specific professional requirements may still be required depending on where you intend to build.

A Smart Design for Families and Investors

Plan 190 DU shows how a relatively simple duplex layout can create two comfortable and independent homes.

Whether you're considering a duplex for rental income, multi-generational living, an investment development or two family homes, starting with a good concept plan can make it much easier to discuss the project with builders and determine whether the numbers work.

Download the Free Plan

Visit the Ask the Builder – Free House Plans section at Australian Floor Plans to explore our free designs and other affordable house plans.

Australian Floor Plans
Affordable house designs, concept plans and custom home design services.

Your dream home starts with a good plan.