One of London's largest boroughs by population, though roofing competition here is dense — we position on trust signals rather than price alone. Croydon falls well within the South 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 Croydon, that local knowledge means fewer surprises once work is on site and a team that already understands the borough's typical property stock.
Croydon's size means its housing stock is genuinely mixed rather than dominated by one era. Older, more central parts of the borough have Victorian and Edwardian terraces typical of much of London, many now split into flats or extended over the years. Surrounding these are large swathes of interwar semi-detached and terraced housing from the 1920s and 1930s, the kind of suburban stock common across outer London boroughs of Croydon's scale. There's also a substantial amount of post-war housing, including local authority estates and low-rise blocks built to meet demand from a growing population, plus more recent flat developments in and around the town centre. For a contractor, this variety matters: a Victorian terrace roof, a 1930s semi with a hip roof, and a 1960s block each bring different materials, access issues and repair histories. Roofs and general fabric across this older stock are now reaching an age where repair or replacement is a genuine issue for a large number of homeowners at once, rather than a scattered minority, which is one reason demand across the borough tends to be steady.
A borough with one of London's largest populations means a correspondingly large number of homes needing ongoing repair and refurbishment, and Croydon has no shortage of roofing and building firms competing for that work. That density is good for choice but it also makes the market harder for homeowners to read: adverts and cold callers on price alone are common, and it's not always obvious which quotes reflect proper materials and workmanship and which are cutting corners to win the job cheaply. In a market like this, we'd rather compete on being clear about what's included, showing evidence of past work, and standing behind what we do, than get drawn into a race to the bottom on quoted price. For homeowners and landlords, the practical takeaway is to treat unusually low quotes with some caution and to ask what's actually covered before agreeing anything. Landlords in particular, often managing several properties across the borough, tend to value a contractor who turns up when promised and communicates clearly over one who was marginally cheaper on paper. That reliability gap is often where the real competition sits, even if it's not what's advertised.
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.