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What changes the cost of loft insulation?
A loft insulation quote depends on what is already in the loft, how big and easy to reach it is, whether you want to keep boarded storage, and what has to be cleared or protected first, such as stored items, cables and downlights. This guide does not print a price, so compare what each quote covers.
Last reviewed:What is a loft insulation job?
In a house with a pitched roof and an unused loft, loft insulation usually means rolls of mineral wool or a similar material laid between the ceiling joists, then more laid across the top of them. Sometimes it is loose fill blown or poured between the joists. The aim is to stop heat escaping through the ceiling of the top floor into the cold roof space.
The job can be a short visit to top up thin insulation in an empty loft, or a much longer one that involves clearing stored items, lifting boards, removing damaged old insulation and protecting cables and lights. This guide does not print a price. It explains what makes the job bigger or smaller, so you can compare quotes on the same terms.
QuoteZila starts in Cheshire, with Crewe, Nantwich and Sandbach first, and anyone in the UK can post the job.
What do the regulations say?
Planning Portal's loft insulation page says installing insulation in your loft must meet the minimum energy efficiency values set out in the Approved Documents [S1]. If that is not technically or functionally feasible, the element should be upgraded as far as can be achieved within a simple payback of no greater than 15 years [S1]. Where loft insulation is fitted as part of a roof renovation in which more than 25 per cent of the roof is renewed, the insulation should meet the standards required by the Approved Documents [S1]. It also says care should be taken not to block any ventilation at the edges, at the eaves [S1].
Its ceilings page adds that where more than 25 per cent of a ceiling below a cold loft is replaced, building regulations would normally apply and the ceiling's insulation would normally have to be improved [S2]. For a pitched roof, that would normally mean at least 250 mm of mineral fibre or cellulose fibre as quilt between and across the joists, or loose fill or equivalent [S2]. It says the condensation risk in the roof space has to be assessed [S2].
GOV.UK explains building regulations approval. GOV.UK: building regulations approval. QuoteZila is not affiliated with this organisation.
What changes the quote?
| Factor | What to ask | Why it moves the price |
|---|---|---|
| What is there now | Depth and condition of existing insulation | A top-up is less work than a full lay |
| Loft area | The measured area of the ceiling below | More area, more material |
| Access | Hatch size, ladder, headroom | A small hatch or low roof slows every trip |
| Stored items | Who clears the loft, and where things go | Clearing takes time |
| Boarding | Lift and relay, raise, or leave [S2] | Boarded areas are a separate decision |
| Old insulation | Damp, dirty or damaged material to remove | Removal and waste |
| Ventilation | How the eaves will be kept clear [S1] | Eaves trays or vents may be needed |
| Cables and lights | Where cables run, and any downlights below [S3] | Protecting or lifting fittings clear of insulation |
| Tanks and pipes | Cold water tank and pipes in the loft | Should be insulated, not buried |
| Hatch | Insulating and draught-stripping the hatch | Often left out |
| VAT | Included or extra. Registration applies above £90,000 of taxable turnover [S6] | Changes the total |
Clearing and boarding: the hidden part of the job
If your loft is used for storage, the boxes are the first problem. Before any insulation can go down, the boxes have to come out or be moved to one side, and the installer needs room to work. Ask whether clearing is included or whether you need to do it first.
Boarded areas are the bigger question. Planning Portal notes that the usual approach of insulating between and across joists may be inappropriate if the loft is already boarded out and the boarding is not to be removed [S2]. Options include lifting the boards, insulating, and relaying them on raised supports, or leaving a boarded area as it is and insulating the rest. Each has a different cost and a different result. Ask the installer to explain the choice. Loft boarding costs covers boarding for storage, and loft ladder installation covers the way in.
Ventilation, condensation and the eaves
A loft that is well insulated at floor level becomes colder above the insulation. That is the point, but it means the roof space must stay ventilated so moisture does not condense on the timbers. Planning Portal says care should be taken not to block any ventilation at the edges, at the eaves [S1], and that the condensation risk in the roof space has to be assessed when a ceiling below a loft is replaced [S2].
Ask the installer how they will stop insulation blocking the eaves, and whether they will fit trays or spacers. If there is already mould or wet timber in the loft, deal with the cause first, and ask a roofer to look if water is getting in.
Cables, downlights and the water tank
Cables. Electrical cables may run across the loft floor. Tell the installer where cables are and ask how they will deal with them. If cables look old or damaged, ask an electrician to look before the insulation goes down. This guide gives no electrical steps.
Downlights. Electrical Safety First says downlights should not come into contact with, or be covered by, loft insulation or combustible materials unless they are specifically designed for it, and should have clearance around them so heat can dissipate [S3]. If the room below has downlights, the installer needs to know where each one is.
Light in the loft. If you want a light up there while the work is being done, loft light costs explains that job.
Electrical Safety First: find a registered electrician; NICEIC; NAPIT. QuoteZila is not affiliated with this organisation. You can find a registered electrician through Electrical Safety First.
Tank and pipes. Ask the installer what they will do under and around any cold water tank, and whether the tank and the pipes in the loft will be insulated.
Government schemes and recommendations
Ofgem says the Great British Insulation Scheme delivered improvements to some of the least energy-efficient homes in Great Britain, mostly single insulation measures, and that it began in April 2023 and ended on 31 March 2026 [S4]. That scheme is closed. Treat any caller offering "free government insulation" with care, and ask which scheme they mean.
GOV.UK has a service that gives recommendations for home improvements if you own a property in England or Wales [S5]. Your energy supplier and your council can tell you about any current support.
Getting the loft ready
Clear a path from the hatch to every part of the floor, or agree that the installer will do it. Bring down anything you want to keep that is near the eaves. Make sure the hatch opens fully and the ladder is safe to use. Tell the installer about anything fragile stored up there, and anything you have seen, such as droppings, wasp nests, damp patches or daylight through the roof.
Wear long sleeves and a mask if you go up there yourself to clear it, because old insulation is dusty and itchy to handle. Walk only on the joists or on boards. The ceiling between the joists will not take your weight.
How do you compare quotes?
Ask every installer to quote for the same job: the loft area, the material, the final depth, what happens to boarded areas, how the eaves will stay ventilated, how cables, downlights, the tank and the hatch will be dealt with, and who clears the loft.
Citizens Advice suggests trying to get written quotes from at least 3 different traders, and says some traders charge for quotes, so ask about this first [S7]. It says a quote is a fixed price and an estimate is just a rough guess [S7]. If a deposit is asked for, push it down as much as possible, do not agree to more than 25%, and always get a receipt [S7].
Walls are the other big insulation job. Cavity wall insulation costs covers that.
Jobs you might post
These are examples, not taken from real job posts.
- "Loft has thin old insulation and nothing stored. Please quote to top it up and insulate the hatch."
- "Half the loft is boarded for storage. Please quote to insulate the unboarded half and say what you would do with the boarded part."
- "Three downlights in the bedroom ceiling below the loft. Please quote for insulation and say how you will keep them clear."
Posting a loft insulation job
Photos of the loft floor, the eaves, any boarding and the hatch help an installer quote. Your job goes to up to five matched local businesses [QZ2]. QuoteZila is free for customers and local businesses [QZ1].
Honest status: QuoteZila is new. We're starting in Cheshire, beginning with Crewe, Nantwich and Sandbach, and growing area by area. Anyone in the UK can still post a job or register a business. How fast you get quotes depends on how many local businesses have joined near you. Businesses can register and receive jobs straight away. We don't check insurance, qualifications or registrations, so please check these yourself before you hire.
Posting a job is not open yet
Questions about loft insulation costs
How much does loft insulation cost?
This guide does not print a figure. An empty, easy loft that only needs a top-up is a different job from a loft full of stored boxes with boarding to lift and old insulation to clear. Ask each installer to say what they will lay, how deep, over what area, and what clearing and protecting is included.
How thick should loft insulation be?
Planning Portal says that where more than 25 per cent of a ceiling below a cold loft is replaced, building regulations would normally apply, and for a pitched roof this would normally mean at least 250 mm of mineral fibre or cellulose fibre quilt laid between and across the joists, or loose fill or equivalent. That is the figure for that situation. Ask the installer what depth they propose for your loft and why.
Can I keep my boarded loft and still insulate?
Often, but it changes the job. Planning Portal notes that adding insulation between and across joists may be inappropriate if the loft is already boarded and the boarding is not being removed. Ask whether the installer will lift and relay the boards, raise them on supports, or insulate elsewhere. Loft boarding costs covers boarding itself.
Do I need planning permission or building control?
Planning Portal says planning permission is not normally required for fitting insulation where there is no change in external appearance, unless the building is listed or in a conservation area. For building control, its loft insulation page says loft insulation must meet the minimum energy efficiency values in the Approved Documents. Ask your council's building control team if you are unsure.
What about the lights in the ceiling below?
Electrical Safety First says downlights should not come into contact with, or be covered by, loft insulation or combustible materials unless they are specifically designed for it. Tell the installer where any downlights are, and ask how they will keep them clear.
Is there still a government scheme for free loft insulation?
Ofgem says the Great British Insulation Scheme began in April 2023 and ended on 31 March 2026. GOV.UK has a service that gives recommendations for home improvements if you own a property in England or Wales. Ask your energy supplier and your council about any current support.
Does VAT change the price?
It can. A business must register for VAT if its taxable turnover for the last 12 months goes over £90,000. Ask whether VAT is included, and whether any relief applies to your job.
Does QuoteZila check insulation installers?
No. We don't check insurance, qualifications or registrations, so please check these yourself before you hire. You can report a quote or a business from your job page.
This page is general information, not professional or legal advice. QuoteZila does not check Gas Safe, WaterSafe, NFRC, NICEIC or other registrations against the register on your behalf: look them up yourself.
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Sources
- QZ1: QuoteZila product fact. QuoteZila home and FAQ copy.
- QZ2: QuoteZila product fact. QuoteZila FAQ How does getting quotes work.
- S1: Insulation: Building Regulations loft insulation, Planning Portal. Accessed 2026-10-30. https://www.planningportal.co.uk/permission/common-projects/insulation/building-regulations-loft-insulation
- S2: Ceilings and floors: Building Regulations, Planning Portal. Accessed 2026-10-30. https://www.planningportal.co.uk/permission/common-projects/ceilings-and-floors/building-regulations
- S3: Downlights, Electrical Safety First. Accessed 2026-10-30. https://www.electricalsafetyfirst.org.uk/safety-advice/products-and-appliances/lighting/downlights/
- S4: Great British Insulation Scheme, Ofgem. Accessed 2026-10-30. https://www.ofgem.gov.uk/environmental-and-social-schemes/great-british-insulation-scheme
- S5: Find ways to save energy in your home, GOV.UK. Accessed 2026-10-30. https://www.gov.uk/improve-energy-efficiency
- S6: Register for VAT, GOV.UK. Accessed 2026-10-30. https://www.gov.uk/register-for-vat
- S7: Before you get building work done, Citizens Advice. Accessed 2026-10-30. https://www.citizensadvice.org.uk/consumer/getting-home-improvements-done/before-you-get-building-work-done/
- S8: Insulation: planning permission, Planning Portal. Accessed 2026-10-30. https://www.planningportal.co.uk/permission/common-projects/insulation/planning-permission