Summary
A full roof replacement is the largest single roofing investment most homeowners make. Pricing it correctly requires understanding three things: the tile choice (which can vary the material cost by 4×), the insulation upgrade triggered by Part L1B, and the access cost (scaffold for the duration is mandatory, no exceptions). Builders who price the tile and labour without scaffold and insulation lose money.
The decision tree is usually: keep existing tiles or replace; insulate above or below the rafters; underfelt or membrane; mortar or dry ridge/verge. Each choice has a knock-on cost effect of £500-£3,000 on a typical job, and customers rarely understand the implications. A clear written specification reduces disputes during the works.
This guide covers full pitched roof replacement on traditional cut-rafter or trussed roofs. For flat roof replacement see flat roof replacement pricing guide; for slate-specific guidance slate roof pricing guide; for GRP fibreglass fibreglass roof pricing guide.
Key Facts
- Typical roof area — 3-bed semi 80-100m²; 4-bed detached 120-180m²; 5-bed detached or large semi 180-260m²
- Build time — 7-10 working days for a 3-bed semi in good weather; 14-21 days for larger detached
- Scaffold — full perimeter required; £1,200-£3,000 for 3-4 weeks
- Strip-out and disposal — £6-£12/m²; double for slate or where multiple layers
- Tile / slate (supply) — see breakdown below
- Felt / membrane (supply) — breathable underlay £3-£6/m²; non-breathable bitumen felt £2-£4/m²
- Battens — 25 × 38mm or 25 × 50mm treated softwood, £0.80-£1.40/linear m; ~£3-£5/m² of roof when battened at standard gauge
- Ridge tiles — £8-£20 each; ~£12-£25/linear m
- Hip irons, dry verge, eaves felt, vent tiles — £200-£600 in trim and sundries per roof
- Lead valley — £35-£60/linear m supplied; £80-£140/m fitted
- Lead step flashing for chimneys — £80-£200 per chimney repaired
- Insulation upgrade — 270mm mineral wool quilt or equivalent £8-£18/m²; PIR between/over rafters £25-£60/m²; rigid insulation board £30-£70/m²
- Roofer day rate — £200-£280 regional, £260-£360 London
- Roofer + labourer gang — £400-£550/day regional, £500-£700 London
- Skip hire — £250-£400 per skip; typical re-roof generates 2-4 skips
- Building Regulations — Part L1B applies if >25% of any single slope is renewed (insulation upgrade required); BS 5534:2014+A2:2018 fixing requirements
- Notification — Building notice or competent person scheme (Confederation of Roofing Contractors, NFRC Competence Scheme)
- VAT — 20% standard on re-roofing existing dwellings; 5% reduced may apply for empty homes over 2 years
- CSCS card required for roofers on most insurance-backed jobs
- Warranty — 10-25 year manufacturer's tile warranty; workmanship warranty 5-10 years industry standard
Quick Reference Table
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Try squote free →| Tile / Slate Type | Supply £/m² | Total £/m² (Fitted) | Service Life |
|---|---|---|---|
| Concrete interlocking | £20-£35 | £90-£140 | 30-50 years |
| Concrete plain | £40-£60 | £130-£190 | 50+ years |
| Clay interlocking | £35-£60 | £110-£170 | 60+ years |
| Clay plain | £55-£90 | £170-£260 | 80-100 years |
| Natural slate (Welsh) | £55-£90 | £180-£280 | 100+ years |
| Natural slate (Spanish) | £30-£55 | £140-£210 | 80+ years |
| Reclaimed slate | £40-£70 | £160-£240 | 50-80 years |
| Synthetic slate (recycled rubber) | £30-£45 | £120-£170 | 30-40 years |
| Cedar shingles | £40-£65 | £150-£220 | 30-50 years |
| Roof Size | Cost Range (Concrete Interlocking) | Cost Range (Clay Plain) |
|---|---|---|
| 60m² (small terrace) | £5,500-£9,000 | £10,500-£16,500 |
| 80m² (3-bed semi) | £6,500-£12,000 | £14,000-£21,000 |
| 100m² (large semi) | £8,500-£15,500 | £17,500-£27,000 |
| 140m² (detached) | £12,000-£22,000 | £25,000-£37,000 |
| 180m² (large detached) | £16,000-£28,000 | £32,000-£46,000 |
(London rates +25-40%)
Detailed Guidance
Stage Breakdown for a Typical Re-Roof
A standard re-roof on an 80m² semi runs through these stages:
- Scaffold erection (1 day, separate contractor): perimeter scaffold to gable apex
- Strip and dispose (1-2 days): tiles down, felt down, battens off, chimney pots and lead set aside if reusable
- Inspect timbers (during strip): check rafter condition, ridge board, wall plates, fascia. Allow contingency for repair
- Repair carpentry (0-2 days): replace any rotten rafters, ridge piece, wall plates; replace fascia if needed
- Insulation upgrade (0.5-1 day if at ceiling level; longer if between/over rafters)
- Underlay (0.5-1 day): breathable membrane laid bottom-up, 150mm overlap, dressed into gutters with eaves felt
- Counter batten and batten (1-2 days): if counter-battening for ventilation; otherwise battens directly to underlay
- Tile / slate fixing (2-4 days): bottom-up courses, fixed per BS 5534 (every tile fixed in some exposures)
- Ridge and verge (0.5-1 day): mortar or dry systems; mortared verges are now uncommon
- Flashings (0.5-1 day): lead step flashing to chimneys, soakers to valleys, vent tiles
- Strip scaffold (1 day): scaffolder return visit
- Snag and clean (0.5 day): site clean, check gutters clear, photograph completed work
Tile Choice — The Biggest Cost Variable
Concrete interlocking is the budget default — fast to lay, widely available, predictable performance. Clay plain or natural slate is the heritage choice, 2-3× the cost and slower to lay but markedly better appearance and service life. The customer's choice has knock-on effects:
- Plain tiles lay at 150mm gauge (60 tiles per m²) vs interlocking at 230-345mm gauge (10-15 tiles per m²). Labour is 2-3× per m²
- Slate requires nail-fixing of every slate; some interlocking concretes only need every other tile fixed
- Heavier tiles (concrete plain, clay plain) may require structural check of rafter sizing — sometimes additional rafter strengthening
- Listed buildings may require like-for-like replacement under listed building consent; reclaimed material premium £20-£40/m² over new
Insulation Upgrade — Part L1B
When more than 25% of a single roof slope is renewed, Part L1B engages and requires:
- Roof insulation to U-value 0.16 W/m²K if economically and technically feasible (cost of upgrade <50% of cost of works and payback <15 years — most domestic roofs qualify)
- Loft conversion or cold-roof insulation requires equivalent specification
- Warm roof construction (insulation above rafters) typical thickness 100-150mm PIR
If the loft is uninhabited and accessible, the cheapest compliance is to top up the loft floor insulation to 270-300mm mineral wool — £8-£18/m² for materials, fitted in 0.5 day for a typical roof. Where the loft is converted or partially converted, insulation must go between/over rafters, costing £25-£60/m² (between) or £40-£90/m² (over, warm roof).
This is the most-skipped Building Regulation in domestic re-roofing. Building Control inspection of a re-roof should require an insulation spec to be submitted; many roofers and customers ignore it. Charge for it openly — it is a legal requirement, not an upgrade.
Underlay — Breathable vs Non-Breathable
Modern practice is breathable membrane (Klober Permo, Cromar Vent3, Tyvek). It removes the need for ridge or eaves vents in many cases (designer's choice; BS 5534 has detailed requirements). Cost £3-£6/m² supplied.
Older bitumen-impregnated felt ("type 1F") is still used on some specifications, particularly heritage, but requires ventilation strategy (eaves vents + ridge vents). Cost £2-£4/m² supplied.
Where the loft is converted (warm roof construction with PIR between/over rafters), the membrane choice changes — needs to allow drying of timber upward through the construction. Always follow manufacturer's specified system; mixing components voids warranty.
Ridge and Verge — Mortar vs Dry
Mortared ridge is traditional, requires 3:1 sand-cement mortar bedding, looks integrated with the roof. Failure mode: mortar cracks after 25-40 years from thermal cycling. Cost: £12-£25/linear m supplied + fitted.
Dry ridge is mechanical-fixed via brackets and a ventilated ridge roll. Fewer failures, faster install, slightly different appearance. Cost: £25-£40/linear m supplied + fitted.
Mortared verge is traditional, mortar bedded over tile undercloak. Failure mode: mortar cracks; tile creep; weed growth.
Dry verge is plastic or metal trim clipping over tile end. Cheaper, faster, plastic appearance not to all tastes. Cost: £15-£25/linear m fitted.
Most NHBC-warrantied new build now uses dry fix at ridge and verge. Re-roofing on heritage properties usually retains mortared appearance.
Lead Work — Chimneys and Valleys
Every re-roof includes the lead work refresh. Old lead can sometimes be reused (cleaned, reformed) if not fatigue-cracked; usually replacement is more reliable.
- Chimney back gutter + side flashings + front apron — Code 4 lead, ~£200-£400 per chimney including dressing and chasing into brickwork
- Valley lead — Code 5 lead, ~£80-£140/linear m fitted
- Lead saddles, soakers, vent terminals — £20-£50 each
- Lead theft is a real risk; modern alternatives (Easy-Lead, Ubiflex) offer near-lead appearance at lower theft risk
What Often Gets Missed in Pricing
Common omissions that turn a profitable job into a loss:
- Scaffold for the full duration (not 2 weeks if the job runs 4 weeks)
- Disposal of multiple layers (some roofs have 3 layers of tile from previous works)
- Replacement battens (always renew; never reuse old battens — they fail BS 5534)
- Fascia and soffit repair — often discovered rotten once tiles are off; allow 10-20% contingency
- Sarking board (in Scotland and some N England traditional roofs) — replacement £20-£40/m²
- Chimney pot replacement (often cracked) — £80-£250 each fitted
- Solar panel removal and refit (where present) — £600-£1,800 specialist trade
Pricing Walkthrough — 90m² Semi-Detached, Regional
| Item | Cost |
|---|---|
| Scaffold (perimeter, 3 weeks) | £1,800 |
| Strip tiles, felt, battens; dispose | £900 |
| Carpentry repair contingency (rafters, fascia) | £600 |
| Loft floor insulation top-up to 300mm | £1,200 |
| Breathable membrane | £450 |
| Treated battens | £400 |
| Concrete interlocking tile (90m² + 10% waste) | £2,700 |
| Ridge tiles + dry ridge system (12m) | £400 |
| Eaves and gable closures, vent tiles | £350 |
| Lead work — chimney + valley | £550 |
| Roofer + labourer (8 days) | £3,400 |
| Skip hire (2 skips) | £600 |
| Sundries (nails, mortar, sealant, mats) | £250 |
| Building Notice + inspection | £250 |
| Margin 18% | £2,400 |
| Total | £16,250 |
This works out to ~£180/m² fitted with concrete interlocking, fully compliant. Quoted at "£90/m² for tiles and labour" the customer would expect £8,100 — the gap is scaffold, insulation, lead, prelims, fascia repair and margin. Always price the whole job.
Frequently Asked Questions
How long does a roof last before needing replacement?
Concrete interlocking 30-50 years; clay plain 80-100 years; natural slate 100+ years. Underlay typically fails before tiles (bitumen felt 30-40 years; breathable membrane 50+ years claimed but limited track record). Battens fail with felt, accelerated by moisture ingress. A roof "failing" usually means the underlay and battens need replacement even if the tiles are sound — many "re-roofs" reuse 60-80% of the original slates or clay tiles.
Do I need planning permission to re-roof?
No, like-for-like replacement is permitted development. Material change (e.g. slate to tile, tile to metal) may need planning permission in conservation areas, on listed buildings or under Article 4 directions. Always check with the local authority before changing material. Building Regulations apply regardless via Part L1B insulation requirements.
Can I re-roof in winter?
Yes, but with reduced productivity (50-70%) and increased risk of weather damage during exposed periods. Many roofers concentrate winter work on slate or tile patches and storm response, deferring full re-roofs to March-October. Pricing for a winter re-roof typically 5-15% higher to reflect weather-related delays.
Should I top-up old roof insulation when re-roofing?
Legally yes if >25% of slope renewed. Practically yes — heat losses through a poorly insulated roof are 25-35% of dwelling heat loss. Top-up to 300mm mineral wool quilt costs £8-£18/m², payback typically 5-12 years on a gas-heated home. Always quote separately so customer sees the energy upgrade as a value-add, not a hidden cost.
What's the difference between re-felting and re-tiling?
Re-felting (or re-membraning) is stripping tiles, replacing the underlay and battens, and re-laying the same tiles. Cost £45-£80/m². Used where tiles are sound (sound clay plain or slate) but underlay has failed. Re-tiling is full replacement of tiles too. Re-felting on a slate roof typically saves £40-£90/m² in material — well worth doing where the slate is reusable.
Regulations & Standards
Building Regulations 2010 — Part L1B (Conservation of fuel and power, existing dwellings), Part B (Fire safety), Part A (Structure where rafters renewed or strengthened)
BS 5534:2014+A2:2018 — Code of practice for slating and tiling — fixing requirements and ventilation
BS 8000-6:2013 — Workmanship on construction sites: slating and tiling
BS EN 1991-1-4 — Eurocode 1 Part 1-4: Wind actions
NHBC Standards Chapter 7.2 — Pitched roofs
Work at Height Regulations 2005 — risk assessment, edge protection, scaffold
CDM 2015 — Construction Design and Management Regulations
Competent Person Schemes — NFRC, CRC self-certify Building Regs compliance
HSE INDG401 — Working at height: a brief guide
Approved Document L1B — Conservation of fuel and power, existing dwellings
NFRC — National Federation of Roofing Contractors — technical bulletins and competent person scheme
BSI — BS 5534 standard — slating and tiling code
Lead Sheet Training Academy — lead work standards
Marley Eternit — technical guidance — tile manufacturer technical library
Klober UK — underlay and roof ventilation guidance
roof repair pricing guide — individual repair pricing
slate roof pricing guide — slate roof specifics
flat roof replacement pricing guide — flat roof pricing
fibreglass roof pricing guide — GRP fibreglass pricing
roof inspection pricing guide — roof inspection and surveys
loft conversion pricing guide — when re-roofing combines with loft conversion