The 1.2× rule of thumb

A renovation creates equity when the value-uplift is more than the spend. The rough rule: aim for a 1.2× ratio or better (every $1 spent produces $1.20 of property value uplift). Below 1.0× you're destroying equity — you'd be better off doing nothing or moving. Between 1.0× and 1.2× you're break-even at best — viable if you primarily care about lifestyle improvement, not return. Above 1.2× you're adding real equity. The calculator below shows your specific ratio.

The suburb median ceiling — your hard limit

Buyers strongly anchor on what other homes in the suburb sell for at the same bed-count. If your suburb's median sale price for 4-bed/3-bath is $2.4M and your reno produces a $2.8M proposed value (17% above median), the recovery on sale becomes uncertain — the next buyer simply doesn't have the comp evidence to pay materially above median. Over-cap risk is the single most common reason renovations destroy value. The calculator below flags this automatically when your proposed value exceeds 110% of suburb median.

When to walk away and demo-rebuild instead

If your renovation cost is approaching 50% of the post-reno value, demolish-and-rebuild often produces a better outcome — full warranty, modern thermal performance, no concealed defects, cleaner planning approval. The calculator flags this automatically. Add a buffer for the things you can't see until walls come off (asbestos in old fibro, rotted studs, undersized footings) — most renovation contingencies eat themselves on demo discoveries.

NSW-specific reno considerations

(1) If the reno adds a second dwelling (granny flat, dual occupancy), the Design and Building Practitioners Act may apply if any component is Class 2 — adds $45k+ of registered designer overhead. (2) HBCF insurance applies to residential builds over $20k. (3) NSW heritage-listed properties have additional planning controls — heritage approval can add 3–6 months. (4) Council DA is usually required for any extension; CDC may apply for some internal renos. (5) Land tax doesn't apply during a renovation of your principal residence.