Loft, Cavity and Solid Wall Insulation in London
Heat Your Home, Not the Street.
In a home with no insulation, about a third of the heat escapes through the walls and a quarter through the roof. Network Energy finds the leaks, fits the right insulation and tells you straight what funding you can get.
Prefer to talk? Call 020 3689 5196
- Since 2013A Wembley company, founded February 2013
- TrustMark RegisteredLicence 1722036, PAS 2030:2023 certified
- Free SurveyNo-obligation visit and written quote
Where the Heat Goes
A Warm Home Starts With the Walls and Roof.
Heat always moves from warm to cold, and in most homes the quickest way out is straight through the walls and roof. With the price cap up 4% from 1 October 2026, insulation is one of the most cost-effective ways to cut heating bills, and it keeps working for decades.
Through the Walls
About a third of the heat lost from an uninsulated home escapes through its walls.
Through the Roof
About a quarter goes straight out through an uninsulated roof.
Figures: Energy Saving Trust, for a typical uninsulated home.
Loft Insulation
Insulation laid between and over the ceiling joists to the recommended depth, with water pipes, tanks and the loft hatch done too.
- Typical Job
- 1 to 2 hours
- Good For
- Homes with an accessible loft
- Bill Saving
- Around £190 a year
Cavity Wall Insulation
For walls built as two layers with a gap between. We check the walls are suitable, blow insulation into the cavity through small holes, then fill them to match.
- Typical Job
- 2 to 4 hours
- Good For
- Most homes built after the 1920s
- Bill Saving
- Around £200 a year
Internal Wall Insulation
For solid walls with no cavity: insulated boards fitted to the inside of outside walls, then finished ready to decorate. Planned room by room with you.
- Typical Job
- Planned per home
- Good For
- Solid-walled homes
- Bill Saving
- Around £280 a year
Room in Roof Insulation
Loft rooms lose heat through their sloping ceilings, low walls and the small roof spaces behind them. We insulate all of it and keep the room.
- Typical Job
- Planned per home
- Good For
- Loft conversions and attic rooms
Floor Insulation
Cold air under suspended timber floors pulls heat out of a room. Insulating underneath, or over a solid floor, keeps it in and stops draughts.
- Typical Job
- Planned per home
- Good For
- Older homes with timber floors
- Bill Saving
- Around £55 a year
Draught Proofing
Sealing the gaps around doors, windows, floors and loft hatches. One of the cheapest ways to make a room feel warmer straight away.
- Typical Job
- A few hours
- Good For
- Almost every home
Savings: Energy Saving Trust estimates for a typical gas-heated semi-detached home in Great Britain (loft insulated from empty to 270mm), using July 2026 fuel prices. Your savings will vary. Electric storage heaters are also on our licence, for homes without gas.
Know Your Home
What Kind of Home Do You Have?
When a house was built tells you a lot about how it loses heat. Pick the one closest to yours to see what usually works, then add it to your survey request.
Illustration: where a typical victorian or edwardian terrace loses heat.
Victorian or Edwardian Terrace
- Walls
- Usually solid brick, with no cavity to fill.
- Biggest Wins
- Loft insulation first, then internal wall insulation and insulation under suspended timber floors.
- Worth Knowing
- Solid walls lose heat faster than cavity walls, so these homes often gain the most. We plan wall work room by room.
Illustration: where a typical 1920s to 1930s semi loses heat.
1920s to 1930s Semi
- Walls
- Often an early cavity wall, and many have never been filled.
- Biggest Wins
- Cavity wall insulation, if the walls are suitable, and topping up the loft.
- Worth Knowing
- Some early cavities are narrow or partly blocked. The survey checks before anything is drilled.
Illustration: where a typical post-war house loses heat.
Post-War House
- Walls
- Cavity walls. Some were filled years ago, some never were.
- Biggest Wins
- Topping up thin loft insulation and filling any empty cavities.
- Worth Knowing
- Older fills can settle or get damp. If yours has, we will tell you what it would take to put it right.
Illustration: where a typical flat or maisonette loses heat.
Flat or Maisonette
- Walls
- It depends on the building: cavity, solid or concrete panels.
- Biggest Wins
- Cavity wall insulation for the whole building, loft insulation for top-floor flats, and draught proofing for every flat.
- Worth Knowing
- The freeholder usually has to agree to work on walls and roofs. We can help you work out who to ask.
Cavity or Solid? Check Your Bricks.
If your outside walls are bare brick, the pattern usually gives it away. Our surveyor will confirm it either way.
Rendered or pebbledashed? Measure the wall at a window or door frame: a brick wall 260mm to 350mm thick probably has a cavity, and a thinner one is probably solid.
- Every Brick Long-Side OutProbably a cavity wall: two layers of brick with a gap between them.
- Some Bricks Laid End-OnProbably a solid wall: bricks laid across the wall tie it together.
Funding
Funding, Explained Straight.
Insulation funding has changed a lot this year. The Great British Insulation Scheme has closed, ECO4 ends on 31 December 2026, and there will be no replacement supplier scheme. Here’s what’s actually available now.
Warm Homes: Local GrantOpen
Government grants for insulation and other upgrades in lower-income homes, free to eligible owners and private tenants. In Brent and most of London, it’s run by the Greater London Authority for the local councils.
Who it’s for: homes rated EPC D to G where household income is £36,000 or less, someone gets a means-tested benefit, or the postcode is on the eligible list. Apply free at gov.uk/apply-warm-homes-local-grant. Nobody should charge you a fee.
VAT-Free InsulationUntil 31 Mar 2027
Installing insulation in a home is zero-rated for VAT until 31 March 2027, then 5%. If you’re paying for it yourself, now is a good time.
Who it’s for: every homeowner and landlord paying for insulation.
Paying YourselfAny Time
Insulation pays its way. The Energy Saving Trust puts the saving at around £190 a year for insulating an empty loft and £200 a year for cavity walls in a typical semi. You get a fixed written quote after a free survey, and time to decide.
ECO4 and the Great British Insulation SchemeClosing
The Great British Insulation Scheme closed on 31 March 2026. ECO4 ends on 31 December 2026 and is finishing work already under way. The government has said there will be no replacement supplier scheme.
Checked 14 October 2026. Schemes change, so we confirm what applies to your home at the survey.
Had a Cold Call About an Insulation Grant?
Warm Homes grants are free to apply for, and nobody should charge you a fee to ‘secure’ one. Before you let anyone in, ask for their TrustMark licence number and check it at trustmark.org.uk. Ours is 1722036, and nobody from Network Energy will ask you to sign on the doorstep.
For Landlords
Get Your Lets to EPC C, Without the Guesswork.
From 1 October 2030, every privately rented home in England and Wales will need an EPC of C or above, unless an exemption applies. Landlords are expected to spend up to £10,000 per property, and qualifying work done since 1 October 2025 already counts. Insulation is usually the cheapest way up the scale.
- A Costed Route to COne survey per property, with the measures that get it there and what they cost.
- Every Pound on RecordItemised invoices and certificates, so qualifying work counts towards your £10,000 cap.
- Grants Built InIf your tenants qualify for a Warm Homes grant, it can cover all the work on your first home and half on each further one.
- We Work Around TenantsWe arrange access with them and keep visits short.
- Minimum
For Housing Providers
A Delivery Partner for Funded Programmes.
Since 2013 we’ve installed insulation under Ofgem’s energy company schemes. With social homes due to reach EPC C by 1 April 2030 and new Warm Homes funding for councils and housing associations, we survey, install and hand over the paperwork funded work needs, as one team from start to finish.
Talk to Us About a Programme- PAS 2030:2023 CertifiedEight measures on TrustMark licence 1722036, including loft, cavity wall, internal wall, room in roof and floor insulation.
- Set Up for Funded WorkTrustMark registration and PAS 2030 certification are what council and social housing schemes ask of installers.
- Resident LiaisonLetters, appointments and a named contact for every household.
- Lodgement and HandoverMeasures lodged with TrustMark, and a handover pack for your records.
How We Work
How a Job Runs, From First Call to Sign-Off.
Most of our work is done in a few hours, but the checks before and after matter just as much as the day itself.
Free Survey
A surveyor visits, checks your loft, walls, ventilation and any damp, and takes photos.
Straight Answers
You get it in writing: what we recommend, what funding applies and what you would pay, if anything.
A Date That Suits
We book the work around you. Most loft and cavity wall jobs take a few hours.
Fitted Properly
Trained installers do the work, protect your home as they go and make good afterwards.
Signed Off
We check the finished job and hand over the paperwork, including your guarantee.
What Done Properly Means.
Insulation only works if it suits the building. These are the checks we don't skip.
- Ventilation Checked FirstInsulation and airflow go together, so we check vents and extractor fans before we fill a wall.
- Damp Dealt With, Not Covered UpIf a wall shows damp or damage, we deal with the cause or tell you, rather than insulate over it.
- Photos at Every StageA record of what we found and what we did, so you and any future buyer can see it.
- No Doorstep PressureQuotes in writing and time to think it over. Nobody will ask you to sign on the day.
About Us
Insulating Homes Since 2013, and Still Here.
Network Energy was set up in Wembley in February 2013, the same year the Energy Company Obligation began. Since then we have insulated homes under the Green Deal and the ECO schemes that followed.
The schemes have changed many times, and plenty of installers have come and gone with them. The job hasn’t changed: find where a home loses heat, fix it properly, and explain everything in plain English.
- 2013Network Energy is founded in Wembley, the year ECO and the Green Deal begin.
- 2013 to 2026Homes insulated under the Green Deal and the ECO schemes that followed.
- 2026TrustMark licence 1722036 for eight PAS 2030:2023 measures, as ECO winds down and the Warm Homes Plan begins.
- NowInsulation for homeowners, landlords and housing providers, funded or privately paid.
Company Details
- Registered Name
- Network Energy Limited
- Company Number
- 08410684
- Founded
- 19 February 2013
- Registered Office
- Unit 7 Wharfside, Rosemont Road, Wembley, HA0 4PE
- Phone
- 020 3689 5196
- TrustMark Licence
- 1722036
Questions
Questions We Get Asked a Lot.
Is Free Insulation Still Available?
For some households, yes. The Warm Homes: Local Grant is free to eligible owners and private tenants in homes rated D to G, and eligibility can come from your income, a means-tested benefit or simply your postcode. ECO4 is winding down and ends on 31 December 2026. If you’re paying yourself, insulation is VAT-free until 31 March 2027.
Is Cavity Wall Insulation Right for Every House?
No. It isn’t suitable for cavities narrower than 50mm, walls exposed to driving rain, homes at risk of flooding or walls in poor condition. That’s why we survey first, and we’ll tell you if we think it’s the wrong job for your home.
Can Insulation Cause Damp?
Fitted to suitable walls, with the right ventilation, it shouldn’t. Problems usually come from insulating walls that weren’t suitable or from blocking airflow, so our survey checks both before any work is booked.
What Do Landlords Need to Do by 2030?
Reach EPC C by 1 October 2030 for every tenancy, unless an exemption applies. You’re expected to spend up to £10,000 per property, and qualifying work since 1 October 2025 counts towards it. Reformed EPCs with new ratings are due in the second half of 2027.
How Long Does the Work Take?
A loft usually takes one to two hours and a typical cavity wall two to four. Internal wall, floor and room in roof insulation take longer, and we agree a day-by-day plan with you first.
Will There Be Mess?
Very little. For loft insulation we need clear access to the hatch. For cavity walls we drill small holes in the outside wall and fill them to match when we’re done. Internal wall insulation means moving furniture away from those walls, and we plan that with you.
Is the Work Guaranteed?
Yes. As a TrustMark-registered business, our work carries a guarantee of at least two years, and ECO-funded wall, room in roof and underfloor insulation needs an independent 25-year guarantee. Your written quote names the guarantee and who provides it before you agree to anything.
I Had Cavity Wall Insulation Years Ago. Is It Guaranteed?
It may well be. CIGA, the main cavity wall guarantee provider, can check for a guarantee registered at your address: email guarantees@ciga.co.uk with two proofs of ownership, one of them a current utility bill. A replacement copy costs £60 including VAT. Other providers exist too, so if CIGA has no record, we can help you look.
I Rent My Home. Can I Still Get Insulation?
Yes, with your landlord’s permission. Under the Warm Homes: Local Grant, eligible private tenants pay nothing, though landlords may pay part of the cost. Landlords also have to reach EPC C by 1 October 2030, so it may already be on their list. We’re happy to talk to your landlord.
How Do I Know You’re a Real Company?
We’re Network Energy Limited, registered in England and Wales under company number 08410684, and TrustMark registered under licence 1722036. You can check both online, and you’re welcome to call the office before anyone visits.
Free Survey
Book Your Free Survey.
Tell us a little about the property and we'll call to arrange a time. No cost and no obligation.
- We Call You BackTo book a time that suits you, usually within one working day.
- We VisitAbout an hour to look at the loft, walls and ventilation.
- You Get It in WritingRecommendations, funding and prices, with time to decide.
- 020 3689 5196
- info@networkenergyltd.co.uk
- Based in Wembley, North West London
Thank You. We’ll Be in Touch.
We’ve got your request and will call to arrange your free survey. If it’s urgent, call us on 020 3689 5196.