Solid brick Victorian and Edwardian terraces need insulation specified for their wall type, not a generic system borrowed from cavity-wall housing. Lian Construction runs fabric-first retrofits here — external or internal wall insulation, loft and floor upgrades, ventilation and secondary glazing — sequenced to protect the EPC gain without trapping moisture in the brick.
Croydon overview
Eco Retrofit Refurbishment in Croydon
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 fabric-first eco retrofit and solid wall insulation for Victorian and Edwardian terraces 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.
Typical eco retrofit refurbishment prices in London
Internal wall insulation (full house, plus £200-£500/room)
£5,500–£8,500
Loft insulation top-up
£400–£1,200
Secondary glazing (per window)
£350–£600
General London market guidance, not a fixed quote — actual pricing depends on a site survey. Full breakdown: cost guide.
What Drives the Cost, Line by Line
External wall insulation cost on a Victorian or Edwardian terrace in London runs roughly £150-£200 per square metre installed, working out to about £6,000-£10,000 for a typical mid-terrace and £14,000-£20,000 for a semi-detached house, because a semi has more exposed elevations to cover in insulation, scaffolding and render. Internal wall insulation is priced per square metre of wall rather than per elevation, at roughly £40-£100 depending on whether you specify a breathable board system or a standard PIR system, giving £5,500-£8,500 for a full ground-and-first-floor retrofit, plus £200-£500 per room for taking out and refitting radiators, extending pipework and refitting skirting once the wall has moved inward. On internal wall jobs the disruption cost often exceeds the insulation material cost itself, since every socket and switch on an external wall also needs rewiring further out. Loft insulation top-ups run £400-£1,200 depending on existing depth and joist condition, suspended timber floor insulation is around £100-£110 per square metre - typically £1,400-£2,500, more if boards are rotten and need replacing, which is common enough in Victorian houses with a history of damp that it's worth budgeting for - and secondary glazing to retain original sash or casement windows costs £350-£600 per window, so £3,000-£6,000 for a typical 8-10 window terrace. Combining one wall-insulation route with loft, floor and secondary glazing typically totals £11,000-£20,000 for a mid-terrace, rising to roughly £19,000-£30,000 on a semi-detached property taking the external wall insulation route, since that's the single biggest line item and it scales with the extra elevation area. Installation of the insulation materials themselves - wall, loft and floor - currently qualifies for the 0% VAT rate under the energy-saving materials relief that runs to 31 March 2027 when fitted in a home, but secondary glazing and any general building work invoiced separately from the insulation installation is usually standard-rated at 20%, so it's worth asking a contractor to itemise which parts of a quote fall under which rate rather than assuming one VAT treatment covers the whole job.
How Long Each Stage of a Retrofit Takes
A loft top-up alone is typically a one or two day job. Suspended floor insulation to a typical terrace ground floor, lifting boards, fitting insulation between joists and refitting, usually takes three to five days once furniture and floor coverings are cleared, more if rotten boards turn up once they're lifted. Internal wall insulation to a full ground-and-first-floor house, including removing and refitting radiators, skirting and finishing plaster, realistically runs two to three weeks room by room, partly because a plaster skim coat needs roughly a day of drying time per millimetre of thickness before it can be decorated, so a 2-3mm finish coat wants the best part of a week to dry out properly before paint goes on. External wall insulation on a mid-terrace typically takes two to three weeks from scaffold going up to render curing, weather permitting, since most render systems need settled, dry conditions above about 5°C to cure properly and can't be rushed in wet or frosty weeks; a semi-detached with more elevations to cover runs longer. Where several measures are combined into one retrofit - loft, floor, internal wall insulation to a couple of rooms and secondary glazing, say - the programme is usually six to ten weeks once planning consents, where needed, and Party Wall Act notice periods are factored in, because those notice periods run in parallel with survey and specification work rather than adding pure delay if planned properly from the start. These are typical durations based on how we sequence and resource this work; ground conditions, weather, and what turns up once floorboards or old render come off can move any of them in either direction. Where the retrofit is bundled with a wider refurbishment, the fabric measures get sequenced into that programme rather than run as a separate job afterward, which is usually faster overall.
Fabric-first sequencing: loft and roof first, then walls, floor and openings, heating sized and fitted lastBreathable wood-fibre or mineral wool systems specified on solid brick walls, not foil-backed PIR board that traps moistureVentilation designed and sized alongside every insulation measure so draught-proofing doesn't create the mould it was meant to preventRegular coverage of Croydon and the wider South London area
Signs to look for
Do you need eco retrofit refurbishment in Croydon?
Single-glazed original sash or casement windows in a conservation area, where full replacement has already been refused or is expected to be refused by planning
Consistently cold floors over an unheated cellar or an original suspended timber ground floor with gaps between the boards
An ex-council flat or maisonette of non-traditional construction, large-panel system or concrete cross-wall, where a standard insulation quote hasn't accounted for the different fixing requirements
Rooms that stay noticeably cold even with the heating on, particularly against external solid brick walls facing the street or a side return
How the work is handled in Croydon
Step 1Initial survey of the existing wall, roof, floor and glazing construction, including a baseline moisture reading and a check of the brick bond to confirm solid or cavity wall type, plus a review of the current EPC and any existing ventilation issues
Step 2Fabric-first sequence agreed with you in writing against target U-values from Approved Document L: loft and airtightness first, then walls, then floor, then windows and doors, with heating addressed last so it's sized to the improved building
Step 3Planning position checked against conservation area status and permitted development rights, with a planning application or a Certificate of Lawfulness submitted where the position isn't clear-cut
Step 4Party Wall Act notices served on adjoining owners one to two months before work starts, backed by a written schedule of condition with dated photographs of the shared wall, wherever insulation or render will be fixed over or against a boundary wall
Step 5Building Control route agreed - full plans submission where structural work or consequential energy-performance compliance is involved, building notice for straightforward fabric-only upgrades - with CDM 2015 duties allocated where more than one contractor will be on site
Step 6Structural engineer input obtained where load-bearing elements are affected, such as chimney breast removal or an enlarged opening, with calculations submitted to Building Control before work starts
Step 7Wall insulation installed with the material and fixings matched to the wall type - breathable wood-fibre or mineral wool for solid brick, mechanical fixings suited to concrete panel construction on system-built flats - and checked against the system's BBA certificate
Step 8Floor and roof insulation fitted with junctions detailed so there's no cold-bridging gap where a newly insulated wall meets an un-insulated floor or chimney breast, with each stage inspected and photographed before it's boarded or rendered over
Step 9Ventilation - trickle vents, extract fans or whole-house ventilation - sized to Approved Document F extract rates and commissioned and flow-tested before handover, rather than left as an afterthought
Step 10Snagging agreed, Building Control completion certificate obtained, and a handover pack issued with product data sheets, BBA certificates and warranty documents, plus as-built U-values passed to any separately MCS-accredited installer taking on a heat pump or grant-linked measure
Questions
Eco Retrofit Refurbishment questions in Croydon
How quickly can Lian start fabric-first eco retrofit and solid wall insulation for Victorian and Edwardian terraces in Croydon?
Croydon is part of our regular South 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 Croydon?
Yes. Croydon falls within the area Lian Construction serves across Greater London.
Why do roofing quotes in Croydon vary so much between companies?
Partly it comes down to the sheer number of firms operating in the borough, which pushes some towards competing purely on price. Quotes can also differ because of what's actually included, such as scaffolding, waste disposal, or the quality of materials specified. It's sensible to ask for a breakdown rather than just a total figure, so you're comparing like for like rather than just the headline number.
Can I insulate a single-glazed sash window in a conservation area, or does it need replacing?
In most conservation areas, full replacement of an original single-glazed sash window with modern double glazing is refused by planning, because it changes the appearance and glazing bar profile of a protected elevation. Secondary glazing, a slim second window fitted inside the existing frame, is usually the compliant route, costing roughly £350-£600 per window supplied and fitted - so £3,000-£6,000 for a typical 8-10 window terrace - and it significantly reduces heat loss while cutting external noise by somewhere in the region of 35-45 decibels, leaving the original sash entirely intact and visible from outside.
Will you install my heat pump as part of the retrofit?
No, and we're upfront about that. We carry out the building fabric work - wall, roof and floor insulation, ventilation and windows - but heat pump installation requires MCS accreditation that sits with a separately certified installer, not with us. Where your retrofit includes a heat pump, we coordinate the fabric work to the standard their sizing calculation assumes, pass across the as-built U-values and heat-loss figures so the heat pump is sized against what's actually in the walls rather than an assumption, and hand that specific installation to an MCS-accredited partner, rather than claiming an accreditation we don't hold.
Why recommend insulation before a heat pump, when the heat pump is what heats the house?
Because a heat pump's efficiency, its coefficient of performance, is heavily dependent on how well the building retains heat once the heat pump has put it in. A heat pump on a fabric-first-retrofitted house can typically run at a seasonal coefficient of performance in the region of 3 to 4, whereas the same unit fighting constant heat loss through an un-insulated solid-wall Victorian terrace often has to run at a higher flow temperature just to keep up, dragging that figure down toward 2 to 2.5 and showing up directly as a higher electricity bill. Doing the walls, roof, floor and windows first means whatever heating system goes in afterward is sized correctly and performs as intended.
Talk to Lian Construction about Croydon
Send the site address in Croydon, photos if available, and the eco retrofit refurbishment work you need. We can review the scope and arrange the next step.