Guides & Tips
Insulation, demystified.
Practical, no-nonsense guides for UK homeowners. Written by a PAS2030-certified installer who's spent 20+ years actually fitting these systems — not just writing about them.
External Walls · 12 min read
External Wall Insulation: A Homeowner's Complete 2026 Guide
Everything you need to know about EWI — from how it works and what it costs, to the mistakes that wreck installations and how to avoid them.
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Internal Walls · 11 min read
Internal Wall Insulation: The Complete Guide for UK Homeowners
When IWI is the right call, the four most common systems, what to expect during the build, and why getting the moisture detail right is everything.
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Loft & Roof · 9 min read
Loft Insulation Done Right: 2026 Materials, Costs and Pitfalls
The cheapest, fastest insulation upgrade — but the one most often done badly. How to spec it, install it, and avoid the condensation traps.
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Floor · 10 min read
Floor Insulation: Suspended Timber, Solid Floors and Underfloor Draughts
How to insulate the most overlooked surface in your home, with the right material for suspended-timber and solid-concrete floors.
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Comparison · 10 min read
EWI vs IWI: External or Internal Wall Insulation — Which Is Right for You?
A side-by-side comparison of external and internal wall insulation — cost, performance, disruption, planning and which one suits your property.
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Costs · 11 min read
How Much Does Insulation Cost in 2026? Full UK Price Guide
Real 2026 prices for loft, floor, internal wall and external wall insulation — by measure, by property size and per m² — so you can budget before you call anyone.
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Reference · 9 min read
Insulation Glossary: Every Term Explained (A–Z)
Plain-English definitions of every insulation term you’ll meet — U-values, cold bridging, PAS 2030, vapour control, EWI, IWI and more.
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Property Types · 10 min read
How to Insulate a 1930s Semi-Detached House
The 1930s semi is Britain’s most common home — and has a predictable set of weak spots. Here’s exactly which insulation measures pay off, in what order, and what they cost.
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Property Types · 11 min read
How to Insulate a Victorian Terrace
Solid 9-inch walls, suspended floors and conservation-area rules make the Victorian terrace a special case. Here’s which measures work, what’s allowed, and how to keep the period fabric safe.
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Property Types · 10 min read
How to Insulate an Edwardian House
Edwardian homes share the Victorian solid wall but with bigger rooms, bay windows and generous lofts. Here’s the right insulation plan for this much-loved property type.
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Property Types · 10 min read
How to Insulate a 1960s or Post-War House
Post-war and 1960s homes brought cavity walls, flat-roof extensions and sometimes non-traditional construction. Here’s how to insulate them well and what to check first.
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Comparison · 8 min read
Cavity Wall vs Solid Wall: How to Tell Which You Have
The single most important thing to know before insulating your walls. Here’s how to tell a cavity wall from a solid wall — by age, brick pattern and thickness — and why it changes everything.
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Internal Walls · 8 min read
SWIP Internal Wall Insulation: What It Is and What It Costs
SWIP IWI is a BBA-certified internal wall insulation system with thermally broken studs and a 25-year guarantee — we install it as a manufacturer-approved installer. Here’s how it works, what it costs, and when it’s the right choice.
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Property Types · 9 min read
How to Insulate a Bungalow
Bungalows lose a disproportionate share of heat through the roof because of their large footprint-to-storey ratio. Here’s the right insulation plan, measure by measure.
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Property Types · 11 min read
How to Insulate a Period or Listed Home
Listed buildings and conservation-area homes have strict rules and fragile, breathable fabric. Here’s how to insulate them safely without losing consent or causing damp.
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Property Types · 8 min read
How to Insulate a New-Build or Modern Home
Newer homes are better insulated as standard — but not perfectly. Here’s where modern builds still lose heat and which upgrades are actually worth it.
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Property Types · 9 min read
How to Insulate an Ex-Council Flat or Maisonette
Ex-local-authority flats often have solid or non-traditional walls and shared structures. Here’s what you can insulate, what needs freeholder consent, and where to start.
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Comparison · 9 min read
Hybrid Wall Insulation: Combining EWI and IWI on One Home
Many London homes can’t take external insulation on every wall — so we mix EWI and IWI on the same property. How hybrid wall insulation works, where the junctions matter, and what it costs.
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Costs · 9 min read
What Insulation Really Costs in London: 2026 Report from 450+ Real Quotes
Not estimates — a price report built from 454 quotes we priced and 35 jobs we installed across London and the South-East: every anonymised installed job, real quoted medians per measure, and why finished EWI runs £176–£232/m² all-in.
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How It Works · 10 min read
Breathable Wall Insulation: Why Old Walls Need to Breathe
Solid pre-1919 walls manage moisture by breathing — seal them with the wrong insulation and you trap damp in the fabric. The physics in plain English, and the breathable build-ups we specify (used on 103 of our real quotes).
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Problems & Fixes · 10 min read
Condensation, Damp and Mould After Insulation: What Goes Wrong
Insulation done badly can cause the damp it should prevent. Where condensation actually comes from, why interstitial condensation is the silent one, and how proper design keeps insulated walls dry.
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Problems & Fixes · 8 min read
Ventilation After Insulating: The Step Bad Installers Skip
Make a house more airtight and the moisture has to go somewhere. Why roughly 1 in 8 of our insulation quotes includes ventilation works, and what good extract and background ventilation look like.
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External Walls · 9 min read
EWI Render Systems Compared: Silicone, Mineral and Acrylic
The render is the part of EWI you look at for 30 years. Silicone, mineral and acrylic thin-coat systems compared on flexibility, breathability, colour and cost — from an installer that details render on nearly 100 quotes.
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Loft & Roof · 8 min read
Loft Boarding Over Insulation: Storage Without Crushing Performance
Board straight onto joists and you squash 270mm of insulation to 100mm. How raised loft legs keep full depth and full storage, what it costs, and the condensation trap of over-boarding.
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Loft & Roof · 9 min read
Room-in-Roof and Rafter Insulation Done Right
Converted lofts are the hardest space to insulate well: rafter depth, ventilation gaps and dew-point control all matter. How warm-roof build-ups work and what our real rafter jobs involved.
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Costs · 7 min read
Scaffolding and Access: The Hidden Line on Your Insulation Quote
Scaffolding appears on the majority of our EWI quotes and can be thousands of pounds. What drives access costs, when you can share scaffold with other works, and why the cheapest quote often excludes it.
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Problems & Fixes · 9 min read
Spray Foam Insulation Problems: Why We Don’t Install It
Mortgage refusals, un-surveyable roofs, trapped moisture — spray foam is the measure we get asked to fix, not fit. Why surveyors flag it, what removal involves, and the alternatives that don’t devalue your home.
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How It Works · 8 min read
Cold Bridging Explained: Why Corners Go Black
Mould in room corners, around windows and behind wardrobes is usually thermal bridging, not “condensation from drying clothes”. What a cold bridge is, why junctions matter more than walls, and how EWI and IWI treat them.
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External Walls · 8 min read
Do You Need Planning Permission for External Wall Insulation?
Most London EWI is permitted development — but not in conservation areas, on listed buildings or where the council has removed rights. The practical rules, the exceptions we see, and what to check before you book.
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How It Works · 8 min read
Where Your Home Actually Loses Heat
Roof, walls, floor, glazing, draughts — the real proportions behind the famous heat-loss diagram, why solid-wall homes are different, and the order we recommend tackling measures for the fastest payback.
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Problems & Fixes · 9 min read
Cavity Wall Insulation Problems: Failed Retrofits and Fixes
Wet cavities, slumped fill, cold spots and the extraction industry that grew around bad installs. How cavity fill goes wrong, how to tell if yours has, and when extraction plus EWI is the honest fix.
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Reference · 9 min read
How to Choose an Insulation Installer: PAS 2030, TrustMark and IBGs Decoded
What the badges actually mean, the difference between a manufacturer warranty and a 25-year insurance-backed guarantee, and the questions that expose a bad installer before they touch your walls.
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Comparison · 9 min read
EPS vs Mineral Wool for External Wall Insulation
The two boards that dominate EWI, compared honestly: thermal performance, fire classification, breathability, weight and cost — based on the systems we actually specify across hundreds of quotes.
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How It Works · 9 min read
Airtightness and Vapour Membranes: Insulation’s Invisible Layer
The layer you never see decides whether insulation works: vapour control, airtightness tapes and membranes explained, why they appear on 73 of our quotes, and what skipping them costs you within five years.
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Comparison · 9 min read
PIR vs Wood Fibre vs Insulated Plasterboard for IWI
Three internal wall systems, three different walls they suit. Thermal performance per centimetre, breathability, robustness and cost compared — with the wall types we match each board to on real jobs.
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External Walls · 8 min read
Gutters, Soffits and Pipework: What EWI Does to the Outside of Your House
Adding 100mm to your walls moves everything attached to them. Why gutters, downpipes, soffits and eaves appear on 80+ of our EWI quotes, what gets extended or re-routed, and the details that fail when skipped.
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Costs · 9 min read
What’s in an EWI Quote? Every Line Explained
Boards, basecoat, mesh, beads, reveals, scaffold, making good — a real external wall insulation quote decoded line by line, so you can compare quotes properly and spot what the cheap one leaves out.
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Internal Walls · 8 min read
Why Good IWI Is a Finishing Trade: Plaster, Skirtings and Sockets
Internal wall insulation is judged by the finish: skimming, skirtings, sockets, reveals and cornicing all move. What proper making-good involves — it appears on most of our IWI quotes — and why cheap boarding jobs look cheap.
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How It Works · 8 min read
Window Reveals and Sills: Where Wall Insulation Succeeds or Fails
The 15cm around every window decides whether an insulated wall stays dry. Why reveals and sills appear across our quotes, how they’re detailed in EWI and IWI, and the mould line that betrays a skipped reveal.
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Property Types · 8 min read
Insulating an Extension Properly
Extensions fail differently: junctions with the old house, flat roofs, and walls built to old regs. What we find on real extension jobs and how to bring an extension up to the comfort of the rest of the house.
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Internal Walls · 8 min read
Acoustic and Party-Wall Sound Insulation
Thermal boards do little for noise — sound needs mass, isolation and absorption. What actually quietens a party wall, what we install on real acoustic jobs, and honest expectations about what soundproofing can do.
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External Walls · 8 min read
Pebbledash: Re-render or Insulate Over It?
If you’re paying for scaffold and a new finish anyway, insulating first often costs less than you think. When EWI over pebbledash makes sense, when the dash must come off, and real prices from our jobs.
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How It Works · 7 min read
Insulating Around Bay Windows: EWI and IWI Detailing
Bays are the coldest, hardest-to-detail part of a London terrace: thin walls, big glazing, awkward junctions. How we handle bays in external and internal insulation and why they need their own plan.
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Internal Walls · 7 min read
Insulating Around Chimney Breasts
Live flues, disused stacks and the cold brick column running through your house. When a chimney breast should be insulated, when it must breathe, and the ventilation rules for capped stacks.
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Property Types · 7 min read
Garage Walls and Cold Rooms Above Garages
The bedroom above the garage is the coldest room in thousands of London semis. Why, and the fixes that work: garage ceiling insulation, integral-garage walls, and converted-garage floors.
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Reference · 8 min read
Insulating While You Live There: Room-by-Room Reality
You almost never need to move out. How we sequence IWI room by room, what EWI is like to live through, dust and protection in practice, and realistic disruption timelines from real jobs.
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External Walls · 7 min read
When to Book EWI: Why Render Has Weather Windows
Thin-coat renders cure within temperature and moisture limits, so external wall insulation has seasons. The real weather rules, how installers work around them, and why spring bookings fill first.
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Reference · 7 min read
How Long Does Insulation Take? Real Durations by Measure
A loft top-up is a morning; a whole-house EWI is weeks. Realistic durations for every measure from our own completed jobs, what extends them, and how survey-to-start timelines actually run.
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Reference · 9 min read
Insulation Myths Debunked
“EWI stops walls breathing”, “thicker is always better”, “cavity fill causes damp”, “new windows first” — the myths we hear on surveys every week, tested against building physics and real jobs.
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Still not sure which option fits your home?
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