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Polycarbonate Roof Cost Calculator

Estimate UK 2026 polycarbonate conservatory, lean-to and carport roof cost (corrugated, solid, twin-wall, multi-wall 16/25 mm) by area, sheet type, tint, glazing-bar length and storey. Modelled around Marlon ST Longlife, Palram Suntuf, Brett Martin Marlon multi-wall and Corotherm products.

Polycarbonate Roof Cost Calculator

Estimate UK 2026 polycarbonate conservatory, lean-to and carport roof cost (corrugated, solid, twin-wall, multi-wall 16/25 mm) by area, sheet type, tint, glazing-bar length, eaves trim and storey. Modelled around Marlon ST Longlife, Palram Suntuf, Brett Martin Marlon multi-wall and Corotherm products.

Estimated polycarbonate roof cost
£24,936
Range: £21,196 – £29,923
sheet + glazing bars + perimeter trim + subframe + strip-out + consent + skip
Sheet
£14,520
Glazing bars
£2,112
Perimeter trim
£924
Subframe
£7,040
Strip-out
£0
Consent
£0
Skip / tip
£340

What this calculator estimates

This calculator quotes the all-in installed cost for a UK 2026 polycarbonate roof — for conservatories, lean-tos, carports, pergolas, veranda covers and garden rooms. It separates the bill into the line items NFRC-member installers actually invoice:

  • Sheet cost — Brett Martin Marlon ST Longlife, Palram Suntuf, Sunlite, Corotherm or Onduline Onduclair sheet priced per m², scaled by sheet type (corrugated / solid / twin-wall / multi-wall), tint, storey and access.
  • Self-supporting glazing bars — aluminium snap-cap rafter bars (Brett Martin Self-Support, Palram Snap-Cap, Eurocell Smart Glazing) per linear m, the structural backbone that holds twin-wall and multi-wall sheets.
  • Perimeter trim — F-section side closures, ridge cappings, end caps, eaves trims and breather tape per linear m.
  • Subframe — timber rafters or aluminium framing per m² (sometimes the existing conservatory frame serves as the subframe).
  • Strip-out — removing the existing failed polycarbonate or glass roof.
  • Consent — Building Control fee where applicable for new heated extensions over 30 m².
  • Skip / tip removal — Type 2 plastic recycling skip and waste-transfer charge.
  • Weekend / out-of-hours premium — 25% surcharge for evening, weekend, or expedited schedules.

A minimum call-out fee of £1,280 applies in most UK regions — the labour cost of a 2-person crew, the cut-to-size logistics from the merchant and the cap-flashing labour at the wall-to-roof transition dominate small jobs.

How to use it

  1. Measure the roof area in m². For a lean-to, measure the outer footprint (eave-to-eave × wall-to-eave). A 3.5×4 m lean-to is 14 m².
  2. Pick a sheet type — corrugated for the budget end (£25-40/m² material), twin-wall 6 mm for thermal-performance budget builds, multi-wall 16 mm for premium conservatories, multi-wall 25 mm for upmarket sunrooms or anywhere overheating is an issue.
  3. Pick a tint — clear (89% light transmission, highest passive solar gain, best for north-facing aspects), opal (diffused, eliminates hotspots, +6% sheet cost), bronze (smoke-tinted, reduces solar gain by 25-35%, +8%), solar-control IR coating (Marlon Heatguard rejects 70% solar heat while keeping 60% light, +18%).
  4. Set storey count — single-storey for ground-level lean-tos, two-storey for upper-floor conservatories, three-storey for high-rise rooftop installations.
  5. Pick access — easy is patio with ladder access, moderate is single-storey ridge with scaffold tower, hard is multi-storey requiring hoist.
  6. Set glazing-bar length in linear m. For multi-wall and twin-wall sheets, plan one self-supporting bar per sheet width seam (typical sheet is 1,050-1,250 mm wide).
  7. Set perimeter trim length in linear m. Measure the outside edge of the roof plus the wall-flashing line.
  8. Toggle subframe — ON if building a new conservatory frame, OFF if installing into an existing Eurocell, K2, Synseal or Liniar aluminium frame.
  9. Toggle strip-out — ON if replacing a failed existing polycarbonate or glass roof.
  10. Toggle add-ons — Building Control consent, skip / tip, weekend premium.

Typical 2026 UK polycarbonate roof cost ranges

These reflect 2026 nationwide pricing from Brett Martin, Palram and Corotherm installer surveys, Checkatrade and MyBuilder 2026 quotes data and HomeOwners Alliance Conservatory Cost Guide.

Scope (clear, single-storey, moderate access, with subframe, 20 lm bars and 20 lm trim)2026 installed price
10 m² pergola (corrugated)£1,280 – £1,950
14 m² lean-to (twin-wall 10 mm)£1,800 – £2,650
14 m² lean-to (multi-wall 16 mm)£2,200 – £3,400
25 m² conservatory (multi-wall 16 mm)£3,800 – £5,800
40 m² Edwardian conservatory (multi-wall 25 mm)£6,800 – £10,500
Corrugated polycarbonate, installed£55 – £95 / m²
Twin-wall 6 mm, installed£80 – £115 / m²
Twin-wall 10 mm, installed£100 – £140 / m²
Multi-wall 16 mm, installed£135 – £200 / m²
Multi-wall 25 mm, installed£170 – £250 / m²
Solid 6 mm polycarbonate, installed£105 – £160 / m²
Self-supporting snap-cap glazing bar£32 / lm
F-section perimeter / end-cap / breather tape£14 / lm
Timber or aluminium subframe addition£32 / m²
Bronze / smoke tint uplift+8% sheet cost
Solar-control IR coating uplift+18% sheet cost

Add 15% for two-storey access, 35% for three-storey or higher, and 10-30% for difficult access (hoist required, restricted yard).

Cost drivers

Sheet type. The dominant variable. Corrugated polycarbonate at £55-95/m² installed is the budget benchmark — the wave profile self-drains, the sheet self-supports across 600 mm rafter spacing, and the screw-down install is fast. Twin-wall at 6 mm doubles the thermal performance and adds £25-40/m². Multi-wall at 16 mm triples thermal performance and adds £80-105/m² over corrugated. Multi-wall 25 mm five-wall is the premium spec at £115-155/m² over corrugated.

Glazing-bar system. Multi-wall and twin-wall sheets must be installed with an aluminium snap-cap glazing bar that seals the sheet edge while accommodating thermal expansion (polycarbonate expands 0.065 mm per metre per °C — a 4 m sheet moves 7-9 mm between -10 °C winter and +50 °C summer surface temperature). Self-supporting Brett Martin and Eurocell snap-cap bars run £28-38/lm installed. Skipping the snap-cap system and using exposed screws through the sheet face voids the manufacturer warranty.

Perimeter trim and breather tape. Every multi-wall sheet edge must be sealed against insects and water — the open ends of the internal flutes are sealed at the bottom with adhesive aluminium tape (allowing condensation to escape downward) and at the top with vapour-tight aluminium tape (preventing water entry). The exposed long edges are capped with F-section trim. Plan £12-18/lm all-in.

Subframe. A timber rafter subframe at 600 mm centres runs £24-36/m². An aluminium subframe (popular for retrofit-into-existing-conservatory-base installations) runs £40-60/m². A new K2 / Synseal / Liniar aluminium conservatory frame runs £180-280/m² (separate from the roof line item).

Tint. Clear sheet has the highest light transmission (89% for solid 6 mm, 80-83% for twin-wall). Opal/diffused sheet glazing scatters direct sun and eliminates hotspots, with 7-15% light transmission loss; +6% sheet cost. Bronze smoke tint blocks 25-35% solar gain at the cost of 20% light transmission; +8%. Solar-control IR coating (Marlon ST Heatguard, Palram SunSky Solar Smart) rejects 65-80% of solar heat while keeping 50-60% visible light; +18%. For south-facing UK conservatories where overheating in summer is the dominant complaint, solar-control or bronze is recommended.

Building height and access. Single-storey ground-level installs are baseline. Two-storey work adds 15% for tower scaffold rigging. Three-storey or higher requires cherry-picker or boom-lift rental (£200-£450/day) plus rigging crew.

Per-locale code and standards (UK)

  • BS 5534:2014+A2:2018 — Slating and tiling for pitched roofs and vertical cladding (applies where polycarbonate is integrated into a tiled-roof eaves or rooflight).
  • BS EN 16153 — Light-transmitting flat multi-wall polycarbonate (PC) sheets for internal and external use in roofs, walls and ceilings: requirements and test methods.
  • BS EN 16240 — Light-transmitting flat solid polycarbonate (PC) sheets for internal and external use in roofs, walls and ceilings: requirements and test methods.
  • Approved Document L1B / L (2021) — Conservation of fuel and power in existing dwellings; U-value ≤ 1.5 W/m²K for the roof of a fixed heated conservatory.
  • Approved Document F — Ventilation requirements for new conservatories (trickle vents in glazing or wall).
  • Approved Document B — Fire safety, including external surface spread of flame; polycarbonate is rated to BS EN 13501-1 Class D-s2,d0.
  • Approved Document H — Drainage; conservatory roofs must not back-feed into the main dwelling’s combined sewer.
  • Schedule 2 Part 1 Class 7 GPDO — Permitted development for conservatories ≤ 30 m² attached to a single-storey dwelling.
  • Working at Height Regulations 2005 — Risk assessment and fall protection for all roofing work above 2 m.
  • CDM 2015 — Construction Design and Management Regulations; client and principal contractor duties on domestic projects over £500.
  • BBA Agrément Certificate — Independent third-party certification of polycarbonate sheet for UK use; Brett Martin Marlon, Palram Sunlite, Corotherm all hold current BBA certificates.
  • NFRC Technical Bulletin TB16 — Polycarbonate rooflight installation guidance.

Diagnostic step-by-step

  1. Check the UV-protection layer orientation — premium polycarbonate has a factory co-extruded UV-resistant layer on one face only. The manufacturer’s label tells you which side faces up. Installing the sheet upside-down voids the warranty and the sheet will yellow in 3-5 years instead of 15.
  2. Inspect glazing bars for movement gaps — polycarbonate must be free to expand and contract. The aluminium snap-cap bar holds the sheet edge but should not pinch it; fastener slots are oversized to allow movement.
  3. Inspect breather-tape installation — top edge sealed vapour-tight, bottom edge sealed with porous foil tape (allowing condensation to escape downward). Wrong-side installation traps moisture inside the flutes and grows algae.
  4. Check rafter spacing against the sheet specification — 6 mm twin-wall typically allows 600 mm rafter spacing; 16 mm multi-wall allows 1,000 mm; 25 mm allows 1,200 mm. Wider spacing causes sheet sag and water ponding.
  5. Check the minimum roof pitch — polycarbonate self-supports from 5° (roughly 1:12) minimum pitch.
  6. Check fastener spacing and gasket condition — screws should be spaced 400-500 mm along the rafter, with EPDM rubber washers under each head to seal the hole. Over-tightened screws crack the sheet at the hole.
  7. Verify drainage at the lower edge — the sheet flutes must drain freely at the lower edge into a clear gutter and downpipe. A blocked F-section or perimeter gutter causes water to back up into the flutes.

Avoiding scams and overcharging

UK conservatory roof installs are a frequent target for low-spec contracting:

  • Quotes that use exposed screws through the sheet face (instead of snap-cap glazing bars) — voids manufacturer warranty.
  • Quotes that omit aluminium breather tape — guaranteed algae growth and condensation problems within 2 years.
  • Quotes that use generic polycarbonate without a co-extruded UV layer — yellowing in 3-5 years instead of 15-20.
  • Quotes that install with the UV layer facing down — invisible until it’s too late.
  • Quotes that skip the wall-flashing line at the house-to-conservatory transition.
  • Quotes that omit drip-edge metal at the eave — water blows back under the sheet.

Insist on an itemised quote that explicitly lists the sheet manufacturer and product number, the UV-layer warranty term, glazing-bar manufacturer and product, breather tape part number, fastener manufacturer and EPDM washer rating, and a written 10-year leak warranty. Verify the contractor’s TrustMark, NFRC, FENSA or CERTASS membership through the public registers. Check BBA Agrément for the sheet itself. For attached conservatory roofs, confirm the house attachment will be flashed and integrated with the existing roof and that the rainwater discharge complies with Approved Document H.

Sources: Brett Martin Marlon ST Technical Manual 2026; Palram Sunlite Specifier Guide; Corotherm Installation Manual; Checkatrade and MyBuilder 2026 quotes data; HomeOwners Alliance Conservatory Cost Guide; NFRC Technical Bulletin TB16; BS 5534, BS EN 16153, BS EN 16240; Approved Documents A, B, F, H, L1B; Schedule 2 Part 1 Class 7 GPDO; Working at Height Regulations 2005; CDM 2015; BBA Agrément Certificate database.

Frequently asked questions

How much does a polycarbonate conservatory roof cost per m² in 2026?
Most UK polycarbonate conservatory and lean-to roofs installed in 2026 price between £85 and £190 per m² all-in for the sheet, self-supporting glazing bars, perimeter trim, breather tape and a timber or aluminium subframe. Corrugated polycarbonate (Brett Martin Marlon CS, Palram Suntuf 0.8 mm) is the budget option at £55-95/m² installed. Twin-wall 6 mm runs £80-115/m², twin-wall 10 mm £100-140/m², multi-wall 16 mm £135-200/m² and heavy-duty 25 mm five-wall £170-250/m². A typical 3.5×4 m (14 m²) lean-to in 16 mm multi-wall clear with an aluminium subframe ranges £2,200-£3,400 installed in 2026. Source: Q1 2026 quotes via Checkatrade, MyBuilder, TrustATrader; NFRC 2026 Conservatory Roof Survey; Brett Martin and Palram 2026 installer price lists; HomeOwners Alliance Conservatory Cost Guide.
Should I replace my polycarbonate roof with glass or a solid tiled roof?
Three competing options in the UK 2026 conservatory market. (1) Polycarbonate refresh — replace tired or yellowed sheets with new 25 mm five-wall Marlon ST Longlife at £140-200/m² installed; 12-year UV warranty; keeps the existing aluminium frame; the cheapest and fastest option at 1-2 days. (2) Glass replacement — fit Pilkington Activ self-cleaning sealed units into the existing aluminium frame at £350-550/m²; needs structural calcs and possibly Building Control consent because glass is ~6× heavier; better thermal performance and acoustic performance; better resale value. (3) Solid tiled roof conversion — strip the existing roof and install an Equinox, SupaLite or Guardian system at £900-1,800/m² installed with full structural reinforcement, internal plaster ceiling and Building Regs Approved Document L compliance. Tiled conversions turn the conservatory into a year-round room with proper U-value of 0.18 W/m²K. For overheating south-facing conservatories, the tiled option is the best long-term answer. For budget refresh of a working east/west-facing room, polycarbonate refresh is the right call.
Does a polycarbonate conservatory roof need Building Regulations approval?
Most conservatory and lean-to roof replacements over an existing structure fall under Schedule 2 Class 7 'attached single-storey extension' permitted development and do not need Planning permission, but Building Regulations approval depends on the work. Like-for-like polycarbonate sheet replacement on an existing frame is exempt — no Building Control needed. Adding a polycarbonate roof to a new conservatory under 30 m² that is separated from the main house by external doors is exempt under Approved Document L 5.1 if the conservatory is unheated. Above 30 m², or any conservatory with central heating extended into it, falls under the full Building Regulations and needs L1B compliance (U-value ≤ 1.5 W/m²K for the roof, which 25 mm polycarbonate satisfies; thermal-break aluminium frame; trickle ventilation per Approved Document F). Working at Height Regulations 2005 and CDM 2015 apply to all roof works regardless of permit status. Conservation areas, listed buildings and Article 4 Direction zones need full Planning consent.
How long does a polycarbonate roof last in the UK climate?
UK service life is at the longer end of the global average because UV intensity is lower than southern Europe or the US Sun Belt. Premium multi-wall sheet with a co-extruded UV layer (Brett Martin Marlon ST Longlife, Palram Sunlite Solid, Corotherm Heatguard) carries a 10-year manufacturer warranty against yellowing and impact loss. Real-world UK service life is 18-25 years for premium sheets and 12-18 years for budget sheets without the UV layer. The most common failure modes are: (1) green algae growth on the upper surface from prolonged damp (clean with diluted bleach, never pressure-washed at over 80 bar); (2) yellowing of the upper sheet face after 12-15 years; (3) condensation pooling in the flutes from missing breather tape; (4) snap-cap aluminium bar gasket perishing after 15-20 years. Brett Martin and Palram both offer 'Lifetime Guarantee on UV' on their flagship Marlon ST and Sunlite Solid lines.
What pitch should a polycarbonate roof have?
Minimum pitch is 5° (roughly 1 in 12) for any polycarbonate sheet. Below 5° the sheet drains too slowly, water pools at the lower screw line and seeps into the flutes by capillary action. Brett Martin and Palram both recommend 7-10° as the optimum range for residential conservatories — fast enough to self-clean and self-drain, shallow enough that the room feels open. Above 25° the snap-cap bar gaskets are stressed and the sheet itself may slide downward against the lower retaining strip — for pitches over 25° use a self-supporting bar with positive end-fixing. UK Building Regulations Approved Document H requires conservatory roofs to drain into a separate rainwater system that does not back-feed into the main house gutter — this is the most-commonly-violated detail in DIY conservatory upgrades.
Can I fit polycarbonate sheet myself or do I need a professional?
Corrugated polycarbonate on a small pergola or shed (under 10 m²) is a competent DIY project — the sheet is light, the wave profile is forgiving, the screw-down install is straightforward with a rubber-washer fastener kit. Twin-wall and multi-wall conservatory roofs are more demanding because the snap-cap glazing bar system requires careful cutting, end-cap sealing, breather tape installation in the correct orientation (vapour-tight at the top, porous foil at the bottom), and accurate setting-out of the bars. DIY-installed multi-wall systems frequently fail at the bar-to-sheet seal (admitting water and growing algae in the flutes) or at the eave drip line (water blowing back under the lower edge). Brett Martin and Palram both publish detailed installer manuals and 12-month manufacturer warranties are conditional on installation by a competent person. For a conservatory or carport over 10 m², a NFRC-member installer with a manufacturer-approved warranty is the safer choice.

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