A Castle Hill homeowner had been quoted $18,000 for a full re-roof after 15 years of lichen, moss and tile staining. We restored it for $780 in a single day. Here is exactly how the job ran and the decisions behind it.

This is the full story of one Castle Hill roof clean — what the homeowner had been quoted, what we actually found on site, what we did, how long it took, and what it cost. If you're sitting on a lichen-covered tile roof and wondering whether you're looking at a clean or a re-roof, this one is for you.

The starting point

Three-bedroom single-storey brick home on a standard Hills block, concrete tile roof, built in the late 1990s. The north-facing side was still mostly OK — good sun exposure keeps growth slow. But the south side, shaded by a couple of mature eucalypts next door, was covered in green lichen with visible staining streaks running down the slope.

The owner had already had two quotes before calling us: one for roof restoration (re-point, re-seal, paint) at $12,400, and one for a full re-roof in Colorbond at $18,900. Both roofers agreed the tiles were 'too far gone' to just clean.

This is common. Many restoration and re-roofing operators look at a lichen-covered roof and see a paint-and-seal job. They're not lying — a roof that bad does need something. But they're skipping the step where you first clean it and see what's actually underneath.

What we saw on inspection

When we got up there with a drone and a walked inspection, the tiles were actually in good nick. A handful of hairline cracks on two ridge caps, one slipped tile over the back eave, no major damage. The 'stains' were lichen colonies that had been in place so long their roots had discoloured the surface but not broken into the concrete itself.

The dark streaks between lichen patches? That was the shadow tracking of moisture dripping off lichen during rain — pure surface staining, not algae embedded in the tile.

Our quote went in at $780 for a soft-wash roof clean plus biocide treatment and the two ridge cap re-points. We told the owner: if this doesn't bring the roof back inside the $780 budget, we'll refund and they can go ahead with the restoration quote.

The job itself

Step 1 — Pre-treat (30 minutes)

We pre-treated the entire roof with roof-safe detergent via pump sprayer. Low-pressure, just enough volume to saturate the lichen and kick off the chemical kill. Dwell time: about 20 minutes in the shade, less in the sun.

Step 2 — Soft-wash rinse (90 minutes)

Rinsed at 300-500 PSI with a spray bar, working from ridge to gutter, section by section. No turbo nozzle, no surface cleaner on tiles. Most of the lichen came off in sheets — the root structure breaks down fast once the detergent has done its work.

Step 3 — Gutter + downpipe flush (30 minutes)

All that lichen debris and detergent runoff went straight into the gutters. We vacuum-cleared the gutters, flushed every downpipe, and checked the bunds.

Step 4 — Ridge cap re-point (45 minutes)

The two cracked caps came up with a quick pull-off, fresh flexi-point applied, re-bedded. The slipped tile got nudged back and secured.

Step 5 — Biocide treatment (15 minutes)

Final pass: biocide applied via spray bar across the full roof. This is a preventative film that stops new lichen, moss and algae from taking hold for 12-18 months. It doesn't need rinsing — it cures on the tile surface.

The result

Total time on site: 3 hours 30 minutes. Two operators, one truck, no scaffolding needed. The homeowner came out at the end expecting partial improvement and got a tile colour that almost perfectly matched the (still-lichen-free) north side.

Cost: $780 all in, as quoted. That's $11,620 under the restoration quote and $18,120 under the re-roof quote.

The owner booked us for a follow-up maintenance clean in 24 months. We keep notes on every roof we treat — angle, pitch, material, biocide brand — so when we come back we know exactly what worked the first time.

When cleaning is NOT enough

To be fair: not every lichen-covered roof gets this result. Here's when you genuinely do need restoration or re-roofing instead of cleaning:

Tiles have major cracks (not hairline) across multiple courses — indicates structural damage, usually from prior high-pressure cleaning or hail.
Terracotta tiles with failed glaze — visible as large patches where the glaze has completely lifted. Cleaning won't restore the colour underneath.
Roof leaks already coming through ceilings — cleaning won't fix the water ingress, only the cosmetic issue.
Sarking visibly sagging from beneath tiles — replace sarking first, then consider cleaning after.
Widespread tile slip — more than ~5% of tiles out of position. Re-bedding the whole roof is the right call.

If none of those apply and the roof just looks bad, try a professional clean first. A $600-$900 soft-wash clean with biocide is a genuine alternative that most restoration quotes don't mention because it doesn't pay them.

The takeaway for homeowners

Always get a second opinion from someone whose business is cleaning, not replacing. A cleaning specialist who genuinely can't save the roof will tell you — we've turned plenty of jobs away over the years. But a restoration or roofing company has zero incentive to point you to the cheaper option.

If you're in the Hills District and your roof is staring at you funny, we do free on-site inspections. If we can clean it, we'll quote. If we can't, we'll tell you what you actually need and point you to someone honest who does it.

The starting point

What we saw on inspection

The dark streaks between lichen patches? That was the shadow tracking of moisture dripping off lichen during rain — pure surface staining, not algae embedded in the tile.