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 yearsHouse Extension Builder | Home Renovations | First Story Addition

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(02) 4577 4912


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

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Proud Members of the
Master Builders Association of  NSW since 1968

Home Additions & Extensions

Concord Streetview

Home Renovation in Western Sydney

North Richmond Extension

Winners of the MBA (Master Builders Association of NSW) Housing Award
- Home Extension/Alteration/Renovation (Category $150,000 to $250,000)
For more than 55 years O'Mara has been completing all types of home extensions. These can be called extensions, additions, improvements or renovations.
House extensions of almost every style and design. Renovations to existing homes or heritage listed buildings. Kitchen and bathroom renovations. Removal of internal structural walls to engineer specifications. Re-roofs in colorbond or roof tiles. Single room additions and granny flats. Pergolas, decks and verandahs.
Most people think that extending an existing home is more expensive than building a new home. Although this may be true is some cases often it is more desirable to extend or renovate an existing property. Good quality economical land is now very hard to find and often it makes more sense to extend and renovate.

Often old homes have been built using construction methods now deemed too expensive. There are many old homes built using full brick construction, hardwood or Oregon frames and rafters. Pitched roofs in lieu of trusses. Terra-cotta roof tiles. Hardwood strip floors. High ceilings with decorative ceiling linings or cornices. Many of these older houses are structurally very stable and suit extending onto or renovating rather than just knocking down and re-building an inferior product. In areas such as Pennant Hills, Turramurra, Castle Hill, Hornsby, Kellyville, Dural there are many well built homes that would be much more practical to extend as these areas are full of structurally well built homes that just require some modern upgrades.

Japanese bath

Colonial period style home interior

Wahroonga extension & renovation

Yarramundi renovation 2011
We do not require owners to vacate the house while completing home extensions or renovations. We are experienced and working with clients living in the home during the building process and considering their need for privacy, keep the job safe for the kids and maintain security of the home. 
We start any new building projects within 14 days of council approval and contract signing. Our quotes are very detailed and professionally presented. Our tradesmen onsite get a copy of the building quote (without the price) on site to ensure everyone knows exactly what is to be included in the building project.

New carport using Timbercrete blocks and curved roof

Mosman prestige renovation
After photo
Historic renovation
Glossadia job
After Photo
Our projects include:
Single storey additions
Granny flats
Bathroom renovations
New kitchens 
Pergolas or decks
Wardrobe shelving
New fascia & guttering
Bushfire affected area's
Removal of internal structural walls
Replacement of windows and doors
Cement render with smooth set plaster finish
Rectify roof leaks or damp problems
Convert level to raked ceilings
Rectify sewer blockage problems
Strip flooring sanded and polished
Specialist joinery timber windows & doors
Attic conversions
New skylights
Re-roofs in tiles or colorbond
Fireplaces or slow comustion stoves
Retaining walls and landscaping

We complete home additions in the Hawkesbury Valley, Hills District, Blue Mountains & the Sydney Metro Area. Being based at Mulgrave (near Windsor) makes us central to all of these areas. We also have carpentry crews located from Colo, Penrith, Bateau Bay, Beecroft, Katoomba and Windsor making access to jobs easy.
We can advise on the best methods of how to extend or renovate your existing home economically to your budget. Just contact our office for more details.
St Ives Stairs
St Ives Sunroom

Frenchs Forest Stairs

Home renovation at Budgewoi
on the Cenral Coast

2nd storey extension & renovation at Wahroonga

St Ives internal fireplace

Leura new kitchen 2012

Mt Wilson kitchen 2013

Should we build out or up ?

Often our clients would like to extend their home but they are unsure whether it is more economical and practical to extend out with a couple of rooms or up with a second floor extension. Of course every job is different and we can give you the advice of what we recommend for your project but here are a few suggestions to help you on your way;

- Small 1 or 2 bedroom additions on a block with good access usually are cheaper and more practical to just add out and not up

- Second storey extensions are the best value for money addition you can do but you need to add at least 100m2 onto the existing structure. Our most requested 2nd storey extension consists of a new master bedroom, WIR, ensuite, 2 other bedrooms & a small sitting room. This type of extension is great value for money but you need to add only onto the existing structure so that no concrete and often brickwork is not required. They also need to be at least this big to get better "bang for you buck"

- Master bedroom parents retreats. We have built lots of these. Yes they are more expensive that a standard second storey extension but with raked ceilings, dormer windows, private study and a Juliette balcony thane look fantastic and can really add value to a home. Not to mention the quality of life the clients gets from being able to separate from those noisy teenagers !

Sometimes after we view the property the solution is obvious while other projects its not so easy. There are many factors to consider like sewer main locations, neighbours privacy, shadowing, structural supports, just to name a few. We can also arrange the design concept for both options and just lets the money decide. Best to contact our office so we can point you in the right direction

Wilberforce job
After photo

Exposed hardwood truss

First floor addition in Carlingford

What about a "granny flat" or maybe a duplex ?

Some of our clients want to add a separate dwelling for extra income or maybe for a younger or older relative. This is often called a dual occupancy, a duplex or a granny flat. In principle they are all the same thing but there are slight differences.

A duplex is usually 2 separate dwellings attached by a common wall which shares main services such as sewer & stormwater mains. These are commonly "Strata" titled meaning each owner of each unit owns the inside of each unit and the "body corporate" owns the outside of the dwelling, juts like a block of units. A duplex can in some areas be "Torrens" titled meaning ALL services are separate and nothing is shared, just like any 2 houses in normal street but this is not as common as a Strata duplex. Thera can also be some other community titles and special easements but most duplex's have a common wall & share main services.

A dual occupancy is usually 2 separate dwellings with no common wall. They have their own private courtyard and separate entrance. They can most common on a corner block with 2 street frontages and "Torrens" title. They look just like 2 normal homes but smaller with smaller yards.

A granny flat is typically a small home around 60m2 in the backyard of an existing home. A granny flat is usually smaller than each unit of a duplex or dual occupancy and consists or 1 or 2 bedrooms only, a small combined bathroom / laundry with a open plan living / kitchen area. It can have a small deck or pergola also.

The above is just a generalisation to explain the possible differences and not a strict set rule.

The cost of each can vary greatly and not just because of the cost of construction o the dwelling. Typically a duplex is considered by council as a "multi-unit development" has a lot more requirements. Typically the developer (because that's how they will treat you) will be required to often complete the following on top of construction of the duplex;

- replace boundary fencing at your cost

- landscape the property 

- construct a new driveway

- design special stormwater detention, including pits, kerbs & retaining walls

- pay additional section 94 fee's to council

- pay additional section 73 fees to Sydney water

- prepare Strata or Torrens titel sub-division plans and have them registered at the Office of Land Titles which will allow the separate sale of each unit of the duplex to different parties

A dual occupancy often does not incur such fee's pr special requirements, but it can. A good rule of thumb is if you want to sub-divide the property into 2 titles (whether Strata or Torrens) then you will be up for more costs. But if you just want to build an additional dwelling on the same block and only rent it out it is much less onerous.

A granny flat is the cheapest option but you can't usually sell it off. If its under 60m2 you can often get it approved as a "complying development" by a private certifier without council. This can be a much quicker (not really cheaper) option and you will not have as many construction and fee requirements.

Feel free to contact our office for more information


Mosman luxury renovation
Mt Wilson project

New home using Timbercrete blocks

In our opinion the best way to approach the design is to first have a “concept plan” prepared
This plan is a basic plan that gives the owner a clear idea of what is possible, sufficient information for the builder to accurately tender on the project and enough information to obtain verbal council approval, before the final building plans are prepared and lodged with council
This concept plan would consist of;
- a site plan
- floor plans, drawn to scale with some basic dimensions
- elevations with window sizes
- BASIX requirements
From this concept plan we will then ;
- prepare a construction tender
- price alternatives to the design or material inclusions if required
- prepare a seperate cost to complete the design, prepare profession designs (e.g. engineering) & council fee’s required to lodge a development application (DA)
The best way to have this concept plan prepared is to set a “design brief” for the designer to ensure they design exactly what you require, rather than just redraw your sketch
This design brief should include;
- budget construction cost (this is the most important item) - with this you are likely to design a home over budget that you can't afford, waste time & money - you really need to get this right before you start !
- existing house plans (if available - council usually keeps these on record unless the house is very old)
- a list of rooms required
- a “must list” of inclusions of any items that are important to you 
- a “wish list” of possible items to be included only if the budget allows
- any on-site requirements (e.g. privacy, view, sun, wind, bushfire, etc)
- an outline / photo of the appearance of the house you would like (e.g. country style, federation, modern contemporary, etc)
The designer will then need to visit site to view conditions and confirm your requirements
We usually recommend that you have this concept plan prepared directly with the designer
This way you will always own the rights to the design and no builder can copyright your design 
If you send us your contact details with your design  brief we can give you a reference of a qualified and suitable designer in your area that we regularly work with
If you unsure of what is required on site we can usually do a quick on-line search of google maps / streetview and give you some quick advice over the phone
If a more detailed site inspection is required we can arrange a meeting

New kitchen at Annangrove


Leura new home in snow

New kitchen to Wilberforce project

Mount Wilson croquet pavilion 2013