Custom home builder of extensions, renovations, additions to existing houses in Sydney metro, Hills Shire, Hornsby, Penrith, Hawkesbury & Blue Mountains council area for over 50 years with split level design on sloping land in bushfire area with fire bunkersO'Mara Construction Pty Ltd | We Build Homes, Not Houses | Windsor NSW

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(02) 4577 4912


Unit 1, No.103 Railway Road (North) MULGRAVE NSW 2756

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Large architect designed
new home at Grose Vale
Heritage period style
new home at Nth Richmond

The next step - What to do

Once you have decided to start your building project alot of people ask "What is the next step ?" Project home building has a set process with set rules, probably for good reason. However when you decide to engage a "Custom Home Builder" then the process is completely different. Some people already have their building design complete, engineer designs done and have obtained the council DA approval. If so then that is fine. O'Mara can quote from the plans and documentation. Just contact our office for more information. Bascially project home builders set all the rules but when you engage a custom home builder then the client sets the rules

However some people who only have "idea's" and NO plans then there is a different process. In our opinion these best process to follow when engaging a custom home builder is as follows;

New house built in
high risk bushfire area
in Wismeans Ferry
Pole home built on sloping site
in bushfire area at Kurrajong

Good economical home in Penrith

Complex designs


Where many people go wrong is that they miss this step. They go straight to getting the full working drawings for council approval completed straight away without confirming accurate construction costs and consulating council.

We believe our clients should first prepare a "Concept Plan". This concept plan is a basic plan only, that is drawn to scale with some basic dimensions, elevations, window sizes and a site plan.

From this concept plan we at O'Mara can submit an accurate construction cost, price alternatives (such as changing the construction materials, building method or design) and consult council to obtain "verbal" council approval before the plans are finished and submitted for a DA. Basically this plan needs to show the builder enough information so he can measure & cost everthing accurately and you the client enough information to show you exactly what you will get.


If you can obtain a copy of any existing house plans then designing extensions & renovations will be much cheaper as no or very little site measuring is required. Local councils usually have a copy of these plans that owners can obtain for a small fee, as long as the house is not too old


We can usually give a quick site appraisal simply by looking up google maps and streetview. Due to our many years of experience normally we can evaluate the project quickly and give advice as to the best construction method and process to follow. There is NO fee or charge for this service, just call our office.

Complex or high quality renovations. If the project is very complex by nature or extensive work is required then a more detailed site appraisal may be required. For example you may wish to compare a knock-down rebuild against an extension & renovation. In these cases there may be other factors that need to be considered such as the quality of the services to the property, the stability of the existing footings, structural beams, etc. In these circumstances is may be better to get the builder to come to site to spend a few hours properly evaluating the property and prepare a detailed report for the building designer BEFORE the concept plan is prepared so that the design is completed in the most economical and practical method


Projects without quality plans will usually required a "detailed contour survey" that will show all levels, tree's, services, neighbours and other minor details that are important to the designer. The cost for this is usually around $1,500 to $2,000 paid to the surveyor preparing the report


Unless you have an very clear idea of exactly what you want it is usually NOT a good idea to draw the design yourself. This will usually result in the designer just redrawing your bad idea's We recommend that you prepare a professional design brief to ensure the designer does exactly what you want and does not go off with his/her own "great idea's"

To do this we recomend that your prepare a brief that states;

1. Your BUDGET - everyone has one and needs one no matter what it is, even if its just a range

2. A "MUST LIST" - anything that is essential to the project, the number & name of rooms and things that you really want if you are to undertake the project (eg more storage, garage, privacy screen, etc)

3. A "DON'T LIST" - things you hate (eg 2 storey homes, small bedrooms, small windows, etc

4. A "WISH LIST" - Optional extra items you would like if you can afford it but can live without if it becomes too expensive (eg raked ceilings, timber flooring, Juliette Balcony, etc)

5. "THE LOOK" - a few pictures of other homes you like the look of. This doesn't mean that your house will look exactly like this but it gives the idea to the designer of what features they can include in your design to make your house look modern / country / heritage / arc deco / etc



New Vet Surgery at Kenthurst

Austalian colonial new home
built in the Hawkesbury

North Richmond Extension

Blue Mountains Country Home


The next stage is for the builder to prepare a detailed construction cost. We will submit a very accurate price for construction at NO cost . If requested we can also submit a separate quote to prepare all professional designs and obtain council approval of the owners behalf as a separate cost. The tender can then be revised to suit the owners budget or special council requirements

Leura rear verandah


Once the owner is acceptable to the builders construction cost and the builder is confident that council will approve the project then council approval can be submitted & approved. O'Mara can do this on the owners behalf (at no cost / fee for our services) or the owners can submit it directly. The most important step is however that the owner should NOT sign a building contract until the council approval has been obtained & the builder is ready to start construction

Custom built Australian Colonial Home in a bushfire area

Catherine Hill Bay beachside architectural designed home

New Duplex construction in Windsor

Concord Streetview


The builder will need to check the council DA approval conditions to see if any special requirements or additional designs are required that will affect the construction tender. If there is no other requirements then the builder needs to obtain a "HOME OWNERS WARRANTY" insurance policy and the contracts can be prepared to allow construction to commence. Our standard building contract the the Master Builders Association "BC4 - Fixed price building contract"

Bushfire Bal rated entry door with stone feature corners 

New wood fireplace with stone cladding

Natural cut stone retaining wall

Heritage federation bathroom

Excavation for basement

Steel reinforcement for basement slab finished

Basement slab concrete poured

Load up basement with materials for bricklayers

Bricklayers start laying concrete blocks for basement

Block laying completed

Waterproofing to blockwork

Concrete core fill to concrete blocks to basement

Start brickwork to basement

Basement finished

Spantec joists completed

Installing flooring with step down to bathroom

Bathroom renovation

Kitchen renovation

Windsor new home (internal lift included)

New home at Penrith on Flood affected land