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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

For nearly 60 years O'Mara has been completing all types of home additions and extensions of almost every style and design all over the Sydney, Blue Mountains, Hills & the Hawkesbury area.

Extension at Glossodia

Home extension at Tennyson

Modern extension with metal cladding

Home extension at Kenthurst

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 plaster cornices. Many of these older houses are structurally very stable and suit extending onto or renovating rather than just knocking down and re-building. In many areas of Sydney such as Pennant Hills, Turramurra, Castle Hill, Hornsby, Epping or 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.

Yes extending & renovating can sometimes be more expensive then re-building but in our opinion it often because of poor design. If you already have the bones of a good home it just makes sense to update add to the existing structure and update the finishes. If services need to be upgraded (e.g. stormwater, sewer, water or power) this can be completed at less cost than you might think.

Council is also more flexible with design requirements when compared to approving a new home. Often an extended new home approved by council would not be passed as the exact same project as a new home as new home construction has many more specific requirements.

In our opinion clever design is nearly always a better option than a knock-down re-build

St Ives

Home extension at Windsor

Extension at Budgewoi

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, while keeping the job safe for the kids and maintaining security of the home. 
Council approval for any project usually takes 6-8 weeks but can be longer if there are special site conditions (for example bushfire or heritage)
However many home extensions and renovations can qualify as a "complying development" which make the process much quicker and eliminates the requirement for neighbour notification.
We can start construction of any new building project within 14 days of council approval.

Modern country home design

New spiral staircase

Extension & renovation at Winston Hills



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

Fireplace & living room at Kurrajong

St Ives Sunroom

Frenchs Forest Stairs

Home renovation at Budgewoi
on the Cenral Coast


There is nothing we can't do, we can and do ALL types of extensions & additions, including ;

  • Simple single storey extensions
  • First floor additions or second storey extensions
  • Attic Conversions
  • Heritage building renovations
  • Bathroom, ensuite, powder room & laundry renovations
  • Kitchen renovations (including Butler & outdoor kitchens, kitchenettes & pantries)
  • New decks, pergola's, carports & garages
  • Window & door replacement
  • Existing house cement rendering
  • Services upgrades (mains power, water, sewer, stormwater and gas)
  • Detail joinery (robes, TV cabinetry, study, office, store)
  • External works (driveways, landscaping, retaining walls, fencing, security gates)



2nd storey extension & renovation at Wahroonga

Open fireplace

Mona Vale

Bluestone fireplace & exposed trusses

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 can oversee the project from concept to completion. We can meet on-site to guide you in the right direction of which type of extension or renovation is the most economical and practical. We can then arrange for all the other professional design (e.g. engineering, surveying) required and lodge the plans with council to obtain development approval.
We can also quote from your own plans (with or without council approval)
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 renovation at Penrith

Spiral staircase

Bay window with daybed seat

Barn door


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


Manly Duplex

Two storey duplex in the Hawkesbury

New Duplex construction in Windsor

Duplex near Manly


Upon request, we can customise our tender to make allowance for any special owner requirements or to suit site specific conditions, such as;


  • Frameless shower screen, shower strip drain, rainfall shower rose & rail, wall hung toilet pan, wall concealed toilet cistern, wall hung vanity unit, bottle trap basin waste, recessed mirrored cabinet, free-standing stone bath tub, free-standing bath mixer tap, floor to ceiling wall tiles, wall niche to shower and/or bath, porcelain or marble tiling, mosaic or diagonal pattern tiling


  • 3 phase mains upgrade, dimmers to lights, ceiling fans, stair tread lights, vanity LED or hollywood lighting, upgrade IXL to Neo/Luminate range, LED rocker light switches, Kitchen LED lighting, external sensor lighting, driveway/garden lights,


  • Extra stormwater pits/drains to yard or driveway, kitchen water point for fridge, water filter, chilled/boiled water tap, butler kitchen sink, outdoor kitchen sink, extra garden taps, external yard shower, gas heat / fireplace point, gas BBQ point


  • Internal acoustic wall insulation, Soundchek Gyprock, solid-core internal doors, double glazed windows, floor insulation, drainage & water pipe insulation


  • Alarm system with video intercom, Crimsafe security screens, wall or floor safe (built into wall or floor structure), external sensor lighting, security gates, keyless dead-locks


  • Hardwood timber flooring, timber staircase, stain finish skirting, architraves & window reveals, solid timber internal doors, timber wall/ceiling lining boards

CLEANING EXISTING ROOF SPACE (Below 2ndstorey extension)

  • Clean & vacuum existing ceiling space, remove any vermin & debris, fix any possible small roof openings, install new insulation to existing ceiling


  • Natural fibre insulation or carpet floor coverings, fiberglass or polyester insulation, bamboo flooring, polystyrene cladding, Timbercrete blockwork, GTEK plasterboard, Water tank for recycled water supply


  • Plaster cornices, plaster ceiling panels, feature ceiling roses, plaster arches & corners, chair rails, dado wall paneling, picture rails, mosaic tiling, claw foot baths, federation bathroom fittings & tapware, old-style doors, period style skirting & architraves, gas fireplaces & surrounds, timber windows with colonial bars, terra-cotta roof tiles


  • Decorative CSR “Tempo” cornices, plantation window shutters, fully frameless shower screens, bathroom strip drains, porcelain / marble bathroom tiling, higher 2340mm internal doors, glazed internal doors, semi-commercial aluminum window frames, mirror robe sliding doors, 3 coat wash & wear wall painting finish, feature wall painting/wallpaper


  • Attic truss construction, existing roof frame alterations, attic ladder access, under-stair storage, existing roof door access, flooring & lighting to roof space, specialist robe & linen joinery, study cabinetry, laundry chute, sub-floor access door


  • Open tread staircase design
  • Stair treads upgraded to stained timber finish
  • Balustrade upgrade to glass, chrome/brass, stainless steel cable, timber or wrought iron


  • Higher 9ft (2750mm) ceiling height or Raked ceilings, High-lite windows, Velux openable skylights, Optic fibre skylights to lower level


  • Louvre privacy screens, obscure bathroom / bedroom / staircase glass, acoustic insulation, internal privacy / locksets


  • Gutterguard, Metal wire fly-screens, Fire rated wall cladding, Hardwood fire-rated external timber, Hose reels, Sprinklers system, Shutters to windows & external doors, Fire bunker


  • Wider internal stair width with better “ease-of-going” stair design, wider (870mm) internal doors, lever door handles, shower support rails, shower tiled or fold-up seat, WC support rails, disabled toilet pan, NO-step showers, special access vanity basins, internal passenger lift or inclinator


  • Wood or gas fireplace, gas heat point, heated towel rail, bathroom under-floor heating, heat transfer ducting, insulation upgrade, reversible ceiling fans, window coverings


  • Louvre windows, ceiling fans, solar roof ventilators, eave / gable vents, openable Velux skylights, window sun-hoods, window shutters, tinted or doubled glazed glass, insulation upgrade


  • Split system air-conditioning system
  • Ducted air-conditioning system


  • Carpet or floating timber floor coverings, window furnishings (curtains, blinds or plantation shutters), light fittings


  • Driveway, external paving turf, plants, mulch, irrigation system, garden edging, clothes line, letterbox, fencing, gates, retaining walls

Please contact our office for more information about details of the above items


Fire resistant deck and balustrade

Corrugated metal clad bushfire home

Economical bushfire home with a view

Deck for high risk bushfire area


You can always extend and renovate your home in a bushfire area.

Sometimes the solution is easy and only requires a few minor inclusions (such as fire resistant hardwood & cladding, fire rated window glass and gutter-guard).

Higher BAL rated bushfire risk area's have more requirements, especially in the highest BAL rated FZ - flame zone area's. This includes special fire resistant material to be used as fascia, eaves and under all roofing, fire rated window shutters to all external openings and no external timbers can be used.

There are many items to consider such as sub-floor area protection, access for fire fighters, maintenance, water tank & pump locations.

Owners may also wish to consider using additional protection methods that are NOT required by council or the rural fire service such as hose reels, sprinklers or bunkers but they need special consideration.

The risk of bushfire should be considered at the initial design stage to reduce construction costs and have protection methods that are practical and easy for everyone to use

Contact our office for some free advice on how best to protect your home in a bushfire area when extending or renovating your home.

New kitchen renovation at McGraths Hill

Leichhdart (roof conversion)

Grose Vale home renovation

New laundry joinery