The repair or replace question comes down to three assessments: what percentage of the roof covering is failing or at risk, what is the condition of the underlay beneath it, and does the dominant failure mode affect a section or the whole roof?
As a starting framework: under 20% failing — targeted repair is almost always correct. Over 40% failing — replacement is almost always better value over 10 years. Between 20–40%, the underlay condition and failure type determine the answer.
Original bitumen felt from pre-1990 properties is brittle and permeable after 30+ Highland frost cycles. If the underlay has failed, the roof operates without a secondary weather barrier — any tile movement admits water directly to the deck. This shifts the calculation toward replacement regardless of tile percentage, because you need to open the roof to replace the underlay anyway. Modern breathable membrane has a 50-year design life. Once you are opening a roof to replace 40%+ of tiles, including breathable membrane adds little cost relative to the labour already committed.
On Inverness post-war concrete tile properties, nail sickness changes the calculation categorically. If confirmed across more than 30% of the roof, tiles are not mechanically fixed — any storm can dislodge them. This is not a condition where targeted repair is viable. We see homeowners who have been patching individual tiles for years without realising the wider roof is unfixed. If the same area has been repaired more than twice in five years, nail sickness across the wider pitch is the probable cause.
We assess nail sickness extent, underlay condition and tile coverage across Inverness and Highland. Free survey, written recommendation. Call 01463 262835.
Call 01463 262835Welsh or Caithness slate has a design life of 75–150 years — the framework differs from concrete tile. On a Victorian Inverness property where slate is 100 years old and showing isolated delamination, if 80% is sound, targeted repair is correct and will extend the roof's life by 20–30 years. If widespread delamination is found, re-slating becomes the better answer. We assess each pitch separately and show which areas we consider sound versus at-risk.
Example 1: 1968 Hilton semi, concrete interlocking tile, never re-roofed. Survey finds: nail sickness confirmed on 55% of tiles across both main pitches, original bitumen felt perished and non-waterproof, sarking boards sound. Decision: full replacement. The nail sickness is too widespread for targeted repair to be economic, the felt must be replaced regardless, and the tile is 57 years old. Re-roofing cost: £6,500–£8,200. Cost of continued annual repair attempts over 10 years: estimated £4,000–£6,000 plus emergency call-out costs after storm tile loss, with the same re-roofing requirement at the end of the 10 years anyway.
Example 2: 1987 Westhill detached, concrete interlocking tile. Survey finds: 12% of tiles have lifted due to nail corrosion on the exposed west pitch only — east pitch still mechanically sound. Felt underlay has one isolated failed section above the west eaves. Decision: targeted repair of the west pitch — replace failing tiles, treat exposed section of felt, monitor east pitch annually. Cost: £800–£1,200. Replacement of the full roof not yet justified — east pitch has useful remaining life and the failure is exposure-driven rather than systemic.
Example 3: Victorian Crown area property, Caithness slate. Survey finds: 8% of slates delaminating across the rear north-facing pitch, 2% failed on the visible front pitch, remainder sound with no visible mortar joint issues. Decision: targeted repair on both pitches in matching Caithness slate. The slate design life is 100+ years and 90%+ of the covering is sound. Re-slating is not indicated — it would be expensive and remove sound historic material unnecessarily. Cost: £450–£700 for targeted repair. Result: 20+ additional years of service life on a sound Victorian roof.
When we carry out a repair-or-replace survey, we always provide both options with costs — even when one is clearly preferable. The reason is transparency: you are making a significant financial decision and you should understand the full cost of both paths. On a 1968 Hilton semi with confirmed nail sickness across 55% of the roof, the repair option might be: targeted replacement of the worst 30% of tiles at approximately £1,800, accepting that the remaining 25% nail-sick tiles will require attention within 3–5 years at a further £1,200, and the underlay is perished and will need replacement when the final 25% are done — totalling £3,000–£5,000 over 5 years. The replacement option: £6,500–£8,000 now, 40+ years of additional service life, one mobilisation. When laid out side by side, the decision is usually clear. We lay it out side by side on every survey where the comparison is relevant.
"Survey confirmed 45% nail sickness — replacement was clearly right. Both options were costed honestly. Made the decision easy."
"Expected a full re-roof. Survey confirmed only the rear pitch needed replacing — front still serviceable. Saved around £3,000 versus expectations."
Whatever the roofing question, the right starting point is a professional survey carried out by a roofer who knows Highland conditions and the local housing stock. A survey costs nothing when combined with any roofing project, and £95–£150 as a standalone assessment. The written condition report that follows gives you a clear picture of the current state of your roof, what needs to happen and in what sequence, and what the costs will be.
We have been carrying out roof surveys, repairs and replacements across Inverness and Highland since 2003. NFRC registered. £5m public liability insurance. 10-year workmanship guarantee on all work. Free, no-obligation surveys across the full Highland area. Call 01463 262835 to arrange a visit, or use the contact form on our homepage. We aim to confirm survey appointments within one working day.
For a free survey across Inverness and all of Highland, call 01463 262835. We attend survey appointments within 3–5 working days for non-emergency work. Written quotes are provided within 24 hours of the survey visit. We carry NFRC registration, £5m public liability insurance, and offer a 10-year workmanship guarantee on all roofing work. No call-out fees, no obligation to proceed. If you have read this guide and have a specific question about your property, call us directly — we are happy to advise before you commit to any work.
Signs pointing toward replacement: nail sickness across 30%+ of tiles, failed underlay with multiple tile failures, same section repaired 3+ times in 5 years, or roof over 50 years with widespread deterioration.
Short term yes. Over 5–10 years on a nail-sick roof, annual repairs typically cost more than replacement would have.
Typical repair: £150–£800. Full re-roof: £5,000–£12,000. The break-even calculation depends on repair frequency. Free survey to assess. Call 01463 262835.
Standard policies cover sudden storm damage, not wear and tear replacement. A storm displacing tiles on a nail-sick roof may generate a partial claim.
On roofs over 45 years with confirmed nail sickness, we recommend assessing full replacement rather than continuing to invest in patches.
We do not offer finance directly. Most Inverness homeowners fund re-roofing from savings or a remortgage. Some lenders offer home improvement loans that can cover roofing costs. We provide a written quote for any loan application requiring evidence of the planned expenditure.
April through September gives the most reliable weather windows. August is historically the driest Highland month. We build weather buffer days into all Inverness re-roofing project schedules to account for the unpredictable nature of Highland summer weather.
No call-out fee. Written assessment within 24 hours. No obligation quote before any work starts.
Written quote, itemised by scope and materials. The price we quote is the price you pay.
Written workmanship guarantee. Specified for Highland conditions — not southern UK average specification.
Based in Inverness. Our team surveys your Inverness property and does the work — no subcontractors.
No call-out fee. No obligation.
01463 262835