Knockdown Rebuild in Blacktown, Seven Hills & Baulkham Hills: A Builder’s Guide (2026)

Knockdown rebuild has quietly become the smartest way to get a brand-new home on an established Western Sydney block. You keep the suburb, the schools, the neighbours and the shops you already know, and you replace a tired 1970s or 80s house with something built to 2026 standards. In Blacktown, Seven Hills and Baulkham Hills, we see a knockdown rebuild deliver a better result than an equivalent renovation about eight times out of ten, and for less money once every hidden surprise is counted.

This is the builder’s-eye view of a knockdown rebuild in these three suburbs: what it costs, how long it takes, which council rules apply, and which parts are ours as the builder versus the planner’s. If you want the planning-instrument detail underneath, our planning partner URBA keeps the LEP, DCP and SEE side of the file in order.

Quick answers

• Typical price 2026 (Blacktown & Seven Hills, standard block): $469,000 – $685,000 turnkey for a 4-bed double storey, all-in with demolition, site costs, council fees and BASIX.
• Typical price 2026 (Baulkham Hills, standard block): $549,000 – $895,000 turnkey. Larger blocks and Hills Shire finishes lift the median.
• Total timeline: 10 to 14 months from signed contract to handover. Approvals 8 to 14 weeks (CDC) or 16 to 24 weeks (DA), demolition 3 to 5 weeks, construction 7 to 10 months.
• Pathway: Housing Code Complying Development Certificate (CDC) if your block and design fit the rules; full Development Application (DA) if not. Blacktown flood mapping around Eastern Creek is the most common reason to go DA.
• Do you need to move out? Yes, from the day demolition begins. Plan on 10 to 12 months of alternative accommodation.

Why knockdown rebuild works in these three suburbs

Blacktown, Seven Hills and Baulkham Hills share three features that make knockdown rebuild the right answer more often than not: mature streets on generous blocks, ageing housing stock that costs more to renovate than replace, and land values that already justify a new build. Where the suburbs differ is in council rules, block sizes and the finish level buyers expect.

Blacktown (2148) and the wider Blacktown LGA

Blacktown City Council covers Blacktown itself plus Seven Hills, Quakers Hill, Doonside, Mount Druitt, Glenwood, Marsden Park and The Ponds. Assessment sits under the Blacktown Local Environmental Plan 2015 and the Blacktown Development Control Plan 2015. The DCP was amended with effect from 1 February 2026, so any new lodgement uses the current version.

Older Blacktown blocks, typically 550 to 700 m², are usually big enough for a four-bedroom double storey inside the setbacks: 6 metres from the primary road, 900 mm each side, 3 metres from the rear on the upper floor. Where the block falls more than 1 metre from front to back, the cut-and-fill rules in section 1.7 of Part C (max 900 mm cut, 600 mm fill) usually push us to a split slab or a suspended rear section rather than the traditional slab-on-ground.

Seven Hills (2147)

Seven Hills is a Blacktown LGA suburb, so the same LEP and DCP apply, but the housing stock and block shape are different. A lot of Seven Hills blocks are 500 to 620 m² with 15 to 18 metre frontages, and the existing homes are mostly single-storey brick veneer from the late 60s to early 80s. That is prime knockdown territory: full brick construction, aged plumbing and electrical, and floor plans that were never designed for open-plan family living. Rebuild economics beat renovation here almost every time.

The catch in Seven Hills is drainage. Many of the older lots fall away from the street, so the new stormwater has to go through the downhill neighbour by inter-allotment drainage or, less commonly, to a rear easement. We front-load a civil engineer’s stormwater concept plan into the DA so it doesn’t surface as a variation at Construction Certificate stage.

Baulkham Hills (2153) — The Hills Shire, not Blacktown

Baulkham Hills sits in The Hills Shire, not Blacktown, so the assessment framework is different: The Hills LEP 2019 and The Hills DCP 2012 (and its updates). Blocks are typically larger — 700 m² to 1200 m² is common — with wider frontages that suit five-bedroom double storey homes with a triple garage. Setbacks and site coverage are broadly similar to Blacktown but the FSR maps run higher, and Hills buyers expect Elite or Master Craftsmen finish levels: full brick, engineered stone with waterfall edges, 40mm and 60mm natural stone, frameless showers, ducted zoned A/C and full smart home wiring. Budget accordingly.

DA or CDC: which pathway applies to your block?

Two knockdown rebuild pathways exist in NSW. The Housing Code in State Environmental Planning Policy (Exempt and Complying Development Codes) 2008 allows a new one or two storey house plus the demolition that precedes it as complying development (CDC), on a lot of at least 200 square metres and 6 metres wide at the building line, provided the land is not excluded (heritage items, conservation areas, flood-mapped land above certain levels, bushfire prone land at higher categories, land above 25 ANEF) and the design meets every code standard.

In Blacktown, the flood mapping around Eastern Creek, Breakfast Creek, Bells Creek and the South Creek tributaries is the most common trigger to lodge a DA instead. The other trigger is design: a house that cannot meet the code’s fixed setbacks or site coverage on a corner or irregular lot, or that needs to remove a protected tree, is a DA. Under the DA path, clause 2.7 of Blacktown LEP 2015 (or the equivalent clause of The Hills LEP 2019 for Baulkham Hills) provides that the demolition is included in the DA description, so demolition and new dwelling are one lodgement with one statement of environmental effects.

A CDC is typically approved in 8 to 14 weeks by a private certifier; a DA runs 16 to 24 weeks at Blacktown or The Hills, occasionally longer if the file goes to committee. Our planning and approvals work with URBA on the CDC-versus-DA call before we commission any drawings, because the drawing set and cost differ between them.

What a knockdown rebuild actually costs in 2026

The prices below are turnkey — demolition, site costs, council fees, BASIX, construction and handover — for a four-bedroom home on a standard 550 to 700 m² block with typical site conditions. Corner blocks, sloping blocks, flood-affected blocks and heritage streets all shift the numbers up.

Every number above is a fixed price, not an “estimate” — every line item is documented and the site costs, piering, council fees and BASIX are all included. No surprise variations at slab, no extras at frame stage. See our Knockdown Rebuild Cost Guide for Western Sydney for the deeper 2024 baseline, then add roughly 8 to 12 per cent for 2026 material and labour movement.

The 2026 timeline, month by month

Total: about 10 to 14 months from signed contract to keys in hand, depending on approval path and site complexity. Most Blacktown and Seven Hills rebuilds land at 11 to 12 months. Baulkham Hills often runs a month longer because Hills Shire assessment takes slightly longer and the finish scope is heavier.

What we handle vs what a planner handles

The single most common question we get on a knockdown rebuild is who does what. Broadly:

• The builder (13 Homes) handles: initial site assessment, fixed-price costing, architectural design, engineering, BASIX certification, demolition, site works, construction, finishes, defect period. If you use one of our Modern Essential, Elite or Master Craftsmen packages, we also lodge the CDC directly.
• A planner (URBA) handles: the DA path — statement of environmental effects, LEP and DCP compliance table, cut-and-fill and drainage justification, section 4.15 assessment, response to council requests for information. Where a variation to a numeric control is sought (setback, height, FSR), URBA writes the clause 4.6 variation request.
• The homeowner handles: vacating the property before demolition, arranging alternative accommodation, keeping mortgage and finance in place, sighting and signing off on prestart selections, walking the site at each stage inspection.

For a straightforward CDC path on a compliant block in Seven Hills or Blacktown, the whole thing sits with us as the builder. For a DA path — most Baulkham Hills sites, and flood-affected Blacktown lots — URBA joins the file at the planning stage and stays on until council issues the consent.

Frequently asked questions

How much does a knockdown rebuild cost in Blacktown in 2026?
Between $469,000 and $685,000 turnkey for a standard four-bedroom double storey. That is the fixed price with demolition, site works, council fees and BASIX included. Master Craftsmen custom builds start at $749,000+.

How long does a knockdown rebuild take in Seven Hills?
Roughly 11 months from contract to handover for a CDC-pathway build with no site complications. Add 2 to 3 months if the site needs a DA (older lot with drainage complications, or heritage streetscape). Demolition itself takes 3 to 4 weeks; construction is 7 to 10 months.

Do I need council approval to demolish the old house?
Yes. Under clause 2.7 of Blacktown LEP 2015 (and the equivalent clause of The Hills LEP 2019), demolition of a dwelling requires development consent. In practice the demolition and the new dwelling are lodged as a single DA with one statement of environmental effects, or as a single CDC where the site qualifies. You do not lodge a separate demolition-only application.

Can I rebuild as complying development in Baulkham Hills?
Often yes, but The Hills Shire has more heritage overlays and larger blocks with mature trees than Blacktown, and both push more builds onto the DA pathway. We check the section 10.7 planning certificate on your property before we commit either way.

What if my Blacktown or Seven Hills block is flood affected?
Flood-affected land is excluded from the Housing Code, so a CDC is not available and the rebuild goes to a DA. The DA needs a flood report, floor levels set to Blacktown’s flood planning level (typically the 1% AEP flood plus a freeboard), and often a flood-compatible ground floor. This is the single most expensive constraint to discover late, so we check the flood mapping around Eastern Creek, Breakfast Creek and the South Creek tributaries at first assessment, not at design stage.

Do I need to move out during the knockdown rebuild?
Yes, from the day demolition begins. Most clients rent nearby (Blacktown and Seven Hills clients often stay in the same suburb; Baulkham Hills clients frequently move to Castle Hill or Bella Vista) for 10 to 12 months. Where the timing works, an interstate stint or an extended overseas trip can absorb part of the construction period.

Can I keep my existing pool, driveway or fence?
Yes, anything outside the demolition envelope stays. The demolition zone is defined at design stage, and we coordinate the excavator and asbestos removal (if applicable) to protect anything you want to keep. In Baulkham Hills we often keep an established pool and rebuild around it; in Blacktown and Seven Hills we more often keep the driveway crossover and rear fence and rebuild the rest.

Ready to price a rebuild in your suburb?

We build custom homes and knockdown rebuilds across Blacktown, Seven Hills, Quakers Hill, Marsden Park, Baulkham Hills, Castle Hill, Kellyville, Rouse Hill and the wider Western Sydney growth corridor. Every quote is fixed price. Every line item is documented. Every site cost is included.

Book a free consultation for your specific block and we will walk the site with you, confirm the CDC or DA pathway with URBA, and give you a turnkey fixed price within seven days.