Things to know
Loft, cavity wall, and external wall insulation are genuinely different jobs with different survey requirements, materials, and risks. Quoting them under one generic "insulation" line hides that difference. A cavity wall job in particular needs a borescope survey to check the cavity's condition before installation, since insulating a cavity with existing damp or debris can make problems worse, not better.
Price the pre-installation survey as its own step instead of assuming every property is a straightforward candidate. This is where genuine problems get caught before they become an insulation job gone wrong. It also protects you from being blamed for damp or condensation that was actually caused by installing insulation into an unsuitable cavity.
Ventilation is the detail most likely to get skipped in a quote and most likely to cause a complaint later. Over-insulating a property without adequate ventilation is a real, well-documented cause of condensation and mould. A short note explaining what ventilation is included or recommended alongside the insulation work is a genuine technical safeguard, not merely covering yourself.
Government schemes like ECO4 (due to end in December 2026) can significantly reduce the customer's net cost, but eligibility depends on their specific circumstances and isn't guaranteed. State clearly whether the price shown assumes a grant has been confirmed or is the full cost before any scheme discount, so there's no confusion on the final invoice.
Typical insulation installer line items and UK prices
Indicative ranges, excluding VAT. Rates vary by region (London and the South East run higher) and by job size.
| Item | Unit | Typical range |
|---|---|---|
| Loft insulation top-up to 270mm | per loft (avg) | £400–£800 |
| Cavity wall insulation, semi-detached | per house | £1,000–£2,200 |
| Internal wall insulation | per m² | £80–£140 |
| External wall insulation | per m² | £120–£200 |
| Underfloor insulation (suspended timber floor) | per m² | £30–£60 |
| Loft boarding (storage area) | per m² | £25–£45 |
| Loft hatch insulation + draught seal | per hatch | £60–£150 |
Common insulation installer jobs and how to price them
- Loft top-ups
- Fixed price per loft to a stated depth, with boarding and raised storage priced separately.
- Cavity wall
- Fixed price per property after a borescope survey, with the CIGA guarantee included.
- Solid wall (internal or external)
- Per m², with making good, window reveals and redecoration itemised.
- Underfloor
- Per m² with access method stated.
Regulations and certificates to reference
- Building Regulations (Parts L and C) — cavity wall insulation is notifiable, usually self-certified through a competent person scheme. Loft top-ups are generally not notifiable.
- Ventilation — insulating without maintaining ventilation risks condensation — loft eaves vents and trickle vents should be checked and noted.
- CIGA guarantee (cavity wall) — cavity wall insulation installed by a registered installer usually carries a 25-year CIGA guarantee. Register it and give the customer the certificate.
- PAS 2035/2030 and TrustMark — required for work funded by government energy-efficiency schemes; TrustMark registration covers the consumer-protection side. Schemes change: the Great British Insulation Scheme has closed and ECO4 is due to end in December 2026, so check gov.uk for what's open before promising funding.
Payment terms insulation installers commonly use
- Domestic: payment on completion; deposits for external wall systems.
- Funded schemes: state clearly what the customer pays, if anything.
Read more: Invoice payment terms explained · Payment methods to offer clients
VAT and CIS for insulation installers
VAT
Insulation installed in homes is zero-rated (0%) as an energy-saving material until 31 March 2027 in Great Britain. Supply-only insulation is standard-rated.
Construction Industry Scheme (CIS)
Insulation is building work within CIS when you subcontract to a builder.
General guidance, not tax advice — check your position with HMRC or an accountant.
Read more: Do I need to charge VAT on my invoices? · What must an invoice include? (UK legal requirements)
What this template includes
- Pre-installation survey priced separately (e.g. cavity borescope)
- Insulation type stated (loft, cavity wall, external wall)
- Ventilation consideration noted to avoid condensation
- Grant scheme eligibility referenced
- PDF download or shareable tracked link
Full guide
How to Start an Insulation Installation Business as a Sole Trader
Frequently asked questions
Not on installed insulation in homes in Great Britain until 31 March 2027. It is zero-rated as an energy-saving material. Insulation supplied without installation is standard-rated.
It is notifiable, but registered installers self-certify through a competent person scheme. The customer receives a compliance certificate and a CIGA guarantee.
It can if ventilation is blocked or the wall is unsuitable, such as one exposed to driving rain or with cavity defects. A pre-installation survey and maintained ventilation are essential. Mention both on the quote.
270mm of mineral wool is the common recommendation for lofts. State the depth and material on the quote so the customer can check.
A borescope check confirms the cavity is in suitable condition. Insulating a cavity with existing damp or debris can make problems worse rather than better.
Over-insulating without adequate ventilation is a known cause of condensation. A proper job includes a note on ventilation, not just the insulation material itself.
This should be stated explicitly — schemes like ECO4 depend on individual eligibility, so the quote should be clear whether it assumes a grant or shows the full pre-grant cost.
More free templates
All templates- QuoteWelder / Metal FabricatorA professional quote template for welders and metal fabricators. Itemise material costs, workshop vs on-site labour — download a branded PDF in under a minute.
- QuoteCCTV & Security InstallerA professional quote template for CCTV and security system installers. Itemise wired vs wireless setup, monitoring, and coverage — download a branded PDF in under a minute.
- InvoiceTV Aerial & Satellite InstallerA professional invoice template for TV aerial and satellite installers. Itemise signal diagnosis, mounting, and access equipment — download a branded PDF in under a minute.
Send your first quote today
Free plan stays free forever. No credit card. Branded PDFs in 60 seconds.
Start free