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Insulation & Energy Efficiency in Greenwich

Cavity Wall Insulation in Greenwich, London

For London's 1930s-1980s cavity-wall semis, terraces and ex-council low-rise blocks, Lian Construction installs bead and blown-fibre cavity wall insulation to PAS 2035 standards with a CIGA guarantee, and is upfront about the exposure and condition checks that decide whether a cavity is actually suitable for filling.

Greenwich overview

Cavity Wall Insulation in Greenwich

A large stock of Victorian and Edwardian houses with essentially no dedicated roofing competitor coverage. Greenwich falls well within the South East London ground Lian Construction covers on a regular basis. For cavity wall insulation for 1930s-1980s cavity-wall homes and ex-council low-rise blocks in Greenwich, that local knowledge means fewer surprises once work is on site and a team that already understands the borough's typical property stock.

Greenwich has a large stock of Victorian and Edwardian houses, much of it terraced or semi-detached, built in the decades either side of 1900 as London's suburbs expanded along the riverside and rail lines. As with similar housing across inner and near-inner London boroughs, roofs on these properties are typically slate or clay tile, often with parapet walls, valley gutters, and multiple original chimney stacks. Many houses will have had partial re-roofing, loft conversions, or rear extensions at some point over the past century, which means roof coverings and detailing are frequently mixed ages even on a single property. Bay windows with their own small roofs, and shared or party-wall guttering between terraced neighbours, are common features that need particular care during repair work. Given the age of this housing stock, issues such as slipped or missing tiles, ageing lead flashing around chimneys, and worn valley gutters are the kind of thing homeowners in Greenwich are likely to encounter periodically, rather than one-off problems. Property condition varies a good deal street by street depending on maintenance history, so what one house needs can differ significantly from its neighbour.

With a large stock of Victorian and Edwardian houses and essentially no dedicated roofing competitor coverage in the area, homeowners and landlords in Greenwich are often left choosing between general builders who treat roofing as a sideline, or firms based further afield who may not prioritise smaller local jobs. This gap tends to show up most clearly with urgent repairs, where a slipped tile or a leak after a storm needs someone who can attend quickly rather than fit the job in around larger contracts elsewhere. It also affects planning and quoting for larger work such as full re-roofs or chimney repairs, where a lack of specialist local knowledge can mean longer lead times or less accurate initial assessments. For landlords managing older rental stock, this matters because roof issues left unresolved tend to escalate into damp and interior damage, which is more disruptive and costly to fix than catching problems early. Homeowners undertaking wider refurbishment work, such as loft conversions or extensions, may also find it harder to coordinate roofing specifically as part of a bigger project if there isn't a contractor locally who covers that trade in depth. In practice, this means demand for reliable, responsive roofing and refurbishment work in Greenwich likely outstrips the readily available supply.

Given the concentration of Victorian and Edwardian houses in Greenwich, conservation area and, in some cases, listed building considerations are worth checking before starting roofing or exterior refurbishment work. As in many outer and inner London boroughs with older housing stock, parts of Greenwich may fall within conservation areas, where changes visible from the street, such as replacing roof coverings with a different material, altering rooflines, or adding roof windows to a front elevation, can require planning permission even where similar work elsewhere would be permitted development. Chimney stacks and original architectural detailing are often specifically protected in these areas. It's worth checking with the local planning department or a surveyor early on, since retrospective permission is harder to secure than getting it sorted before work starts. This doesn't apply to every property, and plenty of routine repairs and like-for-like replacements fall outside these controls, but it's a sensible thing to verify given the age of the housing stock.

Typical cavity wall insulation prices in London
ItemTypical range
Typical semi-detached house£1,500–£2,800
Per m²£15–£28/sqm
Extraction and refill (failed existing fill)£2,500–£4,500

General London market guidance, not a fixed quote — actual pricing depends on a site survey. Full breakdown: cost guide.

What actually drives the cost

Wall area is the baseline: expect £30–£55 per m², with smaller properties paying toward the top of that range because most installers apply a minimum call-out regardless of size, and larger detached houses paying nearer £30–£40 per m² once the job clears that minimum. Material choice matters too: mineral wool (rockwool) fill typically costs £35–£45 per m², while EPS or polystyrene bead systems run £45–£55 per m² but perform better in slightly more exposed conditions and are easier to top up later. Access affects labour time, a straightforward two-storey semi with clear side access is quicker than a mid-terrace requiring scaffold or cherry picker access to gable ends. The number of drilling points and how carefully they're made good against existing brick colour and mortar profile adds time on period properties where a poor colour match is visually obvious. Where a previous fill has already failed, urea formaldehyde foam and old, settled mineral wool are the hardest to remove fully, extraction alone runs roughly £25–£35 per m² (about £1,500–£2,800 on an average semi), and because full removal of foam only reliably achieves 60-80% extraction even with specialist equipment, a subsequent EPS bead reinstatement is usually recommended on top, taking a full extract-and-refill job on a semi to £2,000–£4,000 in total. Finally, ECO4 funding, where a household qualifies, can reduce or fully cover the installation cost, which is worth checking before assuming the full retail price applies to you.

How long the job actually takes

A straightforward full-fill on a semi-detached house with good access is typically a one-day job: the survey, drilling grid, injection and making good can all happen within a single visit, and there's no wet trade drying time in the way there is with render or plastering because the material is either blown dry or as a lightly bonded bead that settles within the cavity almost immediately. A mid-terrace or a property needing scaffold to reach upper gable ends can take a day and a half once scaffold erection and take-down are factored in. Extraction jobs take longer: removing an existing failed fill is typically one to two days depending on how compacted the material is and how many extraction points are needed, followed by a separate visit, sometimes the same day, sometimes scheduled a few days later, for the EPS bead reinstatement once the cavity has been inspected and dried. The one genuine weather dependency is that installers generally won't inject on a day of heavy or driving rain, since wet brick skins make it harder to assess whether the cavity itself is already damp before filling, and a false reading there is exactly how an unsuitable wall ends up filled anyway.

We survey every cavity with a borescope before quoting, because a phone-based estimate can't tell you whether a wall is actually suitable for filling.
We check your property's exposure category against BS 8104 wind-driven-rain zones and BS 8208-1 suitability guidance rather than assuming every cavity wall qualifies.
We use the brick bond test to confirm a wall is genuinely cavity construction before recommending cavity wall insulation over solid wall alternatives.
Regular coverage of Greenwich and the wider South East London area

Signs to look for

Do you need cavity wall insulation in Greenwich?

  • Damp staining or discolouration on external brickwork clustered below or around air bricks, which can indicate a blocked vent from a previous poorly executed fill.
  • Render or pebbledash covering the entire external wall, which masks the brick bond and means the cavity-versus-solid check has to be done by survey rather than by eye.
  • An exposed gable end or top-floor elevation facing open ground, a common, or the river, with little shelter from surrounding buildings.
  • Energy bills that seem high relative to what your home's current EPC rating would suggest, particularly if the EPC lists the walls as uninsulated.

How the work is handled in Greenwich

  1. Step 1Initial phone or site conversation to establish your property's age, construction type, and a first check on whether the walls are cavity or solid using the brick bond test.
  2. Step 2Borescope survey of the cavity itself to check width, wall tie condition, existing debris, and whether the cavity is genuinely dry.
  3. Step 3Assessment of the property's wind-driven-rain exposure category against BS 8104 and BS 8208-1 suitability guidance, elevation by elevation.
  4. Step 4Confirmation of material choice (mineral wool, EPS or bonded bead) matched to the survey findings, with a written, itemised quote.
  5. Step 5ECO4 (and, where relevant, any remaining local scheme) eligibility check, so you know your likely out-of-pocket cost before committing.
  6. Step 6Protection of surrounding brickwork, drainpipes, planting and paving, and marking out the drilling grid at the correct height above the damp proof course.
  7. Step 7Drilling and injection of insulation using calibrated equipment to achieve even, full coverage across the cavity.
  8. Step 8Making good of all drill holes to match existing mortar colour and brick coursing, and reinstatement of any air bricks or vents affected.
  9. Step 9Issue of the CIGA guarantee certificate and installation record, confirming material used, date, and coverage.

Questions

Cavity Wall Insulation questions in Greenwich

How quickly can Lian start cavity wall insulation for 1930s-1980s cavity-wall homes and ex-council low-rise blocks in Greenwich?

Greenwich is part of our regular South East London coverage, so once we've surveyed the property we can usually confirm a start date quickly. Send the address and scope and we'll arrange the next step.

Do you cover all of Greenwich?

Yes. Greenwich falls within the area Lian Construction serves across Greater London.

How do I know if my house is in a conservation area?

The local council's planning department will have maps and guidance covering this, usually searchable by postcode on their website. If you're unsure, it's worth checking before booking any exterior work, particularly anything involving the roof, windows, or front elevation, since restrictions can apply even to relatively minor changes. We can flag if something looks like it might need permission when we quote, but the council is the definitive source.

How do I know if my house has cavity walls or solid walls?

Look at the brickwork pattern on the external face. If you see short header bricks appearing regularly among longer stretcher bricks (Flemish or English bond), it's almost certainly a solid 225mm wall with no cavity. If every brick is laid as a stretcher with no headers except at corners, that's stretcher bond and a strong sign of cavity construction. Render or pebbledash can hide this, in which case a survey is needed to confirm.

What is the CIGA guarantee and why does it matter?

CIGA (the Cavity Insulation Guarantee Agency) provides an independent 25-year guarantee for cavity wall insulation installed by CIGA-registered installers, covering rectification work up to a current maximum of £20,000 if the insulation fails through no fault of the homeowner. It transfers automatically to future owners if you sell. Always ask for the CIGA certificate; a company-only guarantee offers no protection if that installer stops trading.

Can cavity wall insulation cause damp?

It can, but only where it's installed in an unsuitable wall, high wind-driven-rain exposure, narrow cavities under 50mm, existing damp, or damaged brickwork and pointing. In those conditions, filled insulation can bridge the cavity and encourage penetrating damp, or produce interstitial condensation as warm indoor air meets its dew point within the fill. A proper borescope and exposure survey before installation is what prevents this, which is why we won't quote a fill without one.

Talk to Lian Construction about Greenwich

Send the site address in Greenwich, photos if available, and the cavity wall insulation work you need. We can review the scope and arrange the next step.

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