Your 15-year-old spotted gum deck is showing its age. The boards have surface checking, the oil finish is fading, a couple of fasteners are loose, and you’re seeing the first signs of mould in the shadiest corner. The question: do you restore it or replace it entirely?
This is the decision that costs Sydney homeowners the most money — because the wrong call can waste $5,000 to $15,000. This guide walks you through the logic, so you can choose with confidence.
The Real Cost of Each Option
Full Deck Restoration (Sanding, Oiling, Repairs)
Typical costs for a 40m² deck:
- Complete surface sand + oiling: $2,500–$4,500
- Fastener replacement / tightening: $300–$800
- Board replacement (1–3 boards): $500–$2,000
- Railing repair / replacement: $800–$2,500
- Total restoration: $4,000–$10,000
Time to completion: 5–10 working days (plus 3–7 days cure time before use)
Full Deck Replacement
Typical costs for a 40m² deck:
- Deconstruction + disposal: $1,500–$2,500
- New hardwood deck (Spotted Gum / Merbau): $8,000–$16,000
- New railing: $3,000–$6,000
- Steps (if needed): $2,000–$4,000
- Total replacement: $14,000–$28,000
Time to completion: 10–15 working days (includes curing)
The obvious takeaway: Replacement is typically 3–4x more expensive than restoration. But the decision isn’t just about cost.
When Restoration Makes Sense
Restore your deck if:
1. The Structural Frame Is Sound
This is the crucial test. The frame (joists, posts, footings, fasteners) is the 70% of your deck you can’t see. If the frame is compromised, restoration is a band-aid.
How to check:
- Get under the deck with a torch and screwdriver
- Press the screwdriver into each joist — it should not penetrate more than 2mm
- Check posts at ground level — they should be solid, not soft or discoloured
- Look for water pooling or settlement (uneven deck height)
If joists are soft in multiple places, or if footings have settled unevenly, the frame has early rot — replacement is the only real fix.
2. Surface Problems Are Cosmetic
Restoration works for:
- ✓ Grey / silvered surface (UV damage)
- ✓ Tannin staining (brown discolouration)
- ✓ Faded oil finish
- ✓ Mould or algae (in isolated patches)
- ✓ 1–4 damaged boards (easy to replace)
- ✓ Loose or corroded fasteners
- ✓ Worn railing finish
These problems sand out and re-oil beautifully. Your deck looks nearly new again, and you’re back enjoying it within 2–3 weeks.
3. Your Deck Is Less Than 20 Years Old
Most hardwood decks (spotted gum, merbau, blackbutt) last 25–40 years with decent maintenance. If your deck is 10–18 years old and the frame is solid, restoration gives you another 10–15 years of life easily.
Decks older than 25 years are candidates for replacement not because they’re always failing, but because the ROI calculation changes (see next section).
4. You Plan to Stay in the Home for 5+ Years
Restoration is an investment in the asset. If you’re selling in 2 years, replacement might add more resale value (new deck = buyer confidence). But if you’re staying, restoration pays for itself in your own enjoyment and saved money.
When Replacement Makes Sense
Replace your deck if:
1. The Frame Has Structural Damage
Red flags:
- Soft joists or posts (screwdriver penetrates more than 5mm) — this is active rot
- Uneven settlement — one corner is noticeably lower than others
- Bolts that won’t tighten because the wood around them has swollen/shrunk
- Cracked posts or diagonal bracing
- Footings that are heaving, cracked, or shifting (foundation failure)
Any of these means the frame has been compromised by water ingress or movement. Restoration can fix the surface, but the underlying problem will come back. You’ll spend $6,000 restoring the deck in 2027, then another $8,000 replacing it in 2029.
Cost per year of use: Much worse than replacement now.
2. More Than 25% of Boards Need Replacement
If you have widespread board damage (not just cosmetic, but warping, checking, or soft spots across 10+ boards), the cost to replace them individually approaches the cost of replacing the entire surface. At that point, rip it up and start fresh — you get a more consistent finish and longer guarantee.
3. You’re Selling Within 2 Years
A restored deck is cosmetically fresh, but buyers see “restored” and think “old deck that needed work.” A new deck says “move in ready, 25+ year lifespan ahead.”
If you’re planning to sell, replacement adds resale value that exceeds its cost. Restoration saves money but might cost you more in sale price and buyer appeal.
4. Your Deck Is Older Than 30 Years
Even with a solid frame, hardwood decks older than 30 years have usually seen significant movement and settling. The fasteners are tired, the boards have stress fractures that won’t sand out, and the underlying structure has adapted to small settling that won’t stay fixed.
A restoration gets you 5–8 more years. A replacement gets you 25–35 years. Do the math on your timeline.
5. You Want to Change the Design
If you want to expand, add a pergola, change the railing style, switch materials, or improve drainage — replacement lets you build it right from the start. Retrofit changes onto an old deck are often more expensive than replacement.
The Decision Matrix
Q1: Is the frame structurally sound?
- YES → continue | NO → Replace
Q2: Are surface problems mostly cosmetic?
- YES → continue | NO (widespread damage) → Replace
Q3: Is the deck less than 25 years old?
- YES → continue | NO → Consider Replacement
Q4: Are you staying 5+ years?
- YES → Restore | NO (selling soon) → Replace
The Middle Ground: Partial Replacement
You don’t always have to choose all-or-nothing:
- Full frame replacement + surface restoration: Rebuild joists and posts, sand and re-oil boards. Costs $6,000–$10,000.
- Board replacement + railing refresh: Replace worn boards, refinish railing, keep frame. Costs $2,000–$4,000.
- Complete decking + keep frame: Remove all boards and railings, rebuild on proven foundation. Costs $10,000–$16,000.
A good builder will propose the option that gives you the best value.
How to Get the Right Diagnosis
- Have a qualified builder inspect the frame (underside, posts, footings)
- Get a written assessment
- Ask for restoration and replacement quotes
- Calculate your ROI based on your timeline and plans
- Decide based on facts, not emotion
We offer free deck assessments. 30 minutes, hands-on inspection, written report, no obligation. We’ll tell you honestly whether your deck should be restored, partially replaced, or completely rebuilt — and what each option costs.
Call us on 0433 334 415 or get in touch here. Let’s make sure you make the right choice for your deck and your budget.
5 Star Decking — NSW Licence 395250C
We restore and rebuild hardwood and composite decks across Sydney. We’re honest about when restoration works and when replacement makes more sense.
