Extending a Victorian terrace, Edwardian semi or ex-council maisonette means forming a new structural opening into a house that predates modern Building Regulations. We handle the structural engineer, Building Control route and Party Wall Act 1996 process together, from rear and side-return extensions through to full two-storey additions.
Ealing overview
House Extensions in Ealing
West London borough benefiting from Wembley-area regeneration, with consistent buy-to-let refurbishment activity. Ealing falls well within the West London ground Lian Construction covers on a regular basis. For rear, side-return, wraparound and two-storey house extensions with structural engineering and Party Wall compliance in Ealing, that local knowledge means fewer surprises once work is on site and a team that already understands the borough's typical property stock.
Ealing's housing stock reflects its position as an established West London suburb that grew steadily through the Victorian and Edwardian periods before filling out further between the wars. Expect a mix of Victorian and Edwardian terraces and semi-detached houses, along with a good number of 1920s and 1930s bay-fronted semis typical of outer London's interwar expansion. Purpose-built mansion blocks and low-rise flats sit alongside the houses in many areas, and more recent infill development has added flats and townhouses on smaller sites over the decades. Properties of this age generally come with the usual list of refurbishment needs: ageing roofs, single-glazed or early double-glazed windows, dated wiring and plumbing, and layouts that often don't suit modern living without some reconfiguration. Loft conversions and rear or side extensions are common ways owners add space rather than move. As with much of outer London, condition varies a lot street to street depending on when a property last had significant work done, which is worth bearing in mind when planning a refurbishment budget or scope.
Regeneration activity around the Wembley area has had a knock-on effect on demand in neighbouring parts of West London, including Ealing, as buyers and renters look slightly further out for value while still wanting reasonable access to improving transport and amenities. This tends to support steady interest in rental property, and landlords in the borough have kept up a fairly consistent pace of refurbishment work, whether that's turning round properties between tenancies, upgrading kitchens and bathrooms to hold rents at a competitive level, or bringing older stock up to current standards for letting. For homeowners, the same regeneration effect can make extending or improving an existing property more attractive than moving, particularly where nearby development is pushing up expectations for finish quality. Because Ealing sees this kind of ongoing buy-to-let and owner-occupier refurbishment demand, competition among contractors for smaller and mid-sized jobs can be steady rather than sparse, so landlords and homeowners are often weighing up contractors on reliability and turnaround time as much as price. Getting quotes early and being clear about scope tends to help avoid delays, especially for landlords working to a fixed window between tenants.
Typical house extensions prices in London
Item
Typical range
Single-storey rear extension (per m²)
£3,000–£5,000
Side-return / wraparound extension (per m²)
£4,500–£5,500
Two-storey extension (per m²)
£2,800–£4,200
Structural opening / RSJ steel beam
£1,800–£4,500+
General London market guidance, not a fixed quote — actual pricing depends on a site survey. Full breakdown: cost guide.
Permitted Development or Full Planning Permission
Most single-storey rear extensions in London fall under the Town and Country Planning (General Permitted Development) (England) Order 2015, which allows a rear extension up to 3m deep for a terraced or semi-detached house, or 4m for a detached house, without a full planning application, subject to height and eaves limits. Go beyond that, up to 6m for a terrace/semi or 8m for a detached house, and you need prior approval under the Larger Home Extension Scheme, which runs as a lighter-touch neighbour consultation process through the council rather than a full application, with a statutory determination period of around six weeks. Side extensions have tighter limits under permitted development, generally single-storey and no wider than half the original house width, which is why most side-return jobs on terraces get combined into a full planning application alongside the rear element instead of trying to split the two. Conservation areas, and Article 4 Directions that specific boroughs apply on top of them, can remove permitted development rights for extensions entirely, meaning even a modest single-storey rear addition needs a full application with an 8-week (or longer, for larger schemes) decision timeline. We check this at the first site visit against your specific borough's local plan and any conservation area or Article 4 status before pricing, because the planning route affects the programme more than the build itself does.
Building Control: Full Plans or Building Notice
Separately from planning permission, every extension needs Building Control sign-off under the Building Regulations 2010, and there are two routes to get it: a Full Plans application, where detailed drawings and structural calculations are submitted and formally approved before work starts, typically taking 5-8 weeks; or a Building Notice, where you can start on site as little as 2 days after submission but without prior approval of the design, meaning any problems get picked up on site inspections instead of on paper beforehand. For a straightforward single-storey rear extension with a well-understood structural opening, a Building Notice can be the faster, lower-friction route. For anything with more structural or ground-condition risk - a side-return with underpinning, a two-storey addition, unusual soil conditions, or a design close to the boundary - we generally recommend Full Plans, because getting the steel sizing and foundation design checked and approved before you dig avoids a stop-work order mid-excavation if Building Control isn't satisfied. Part A covers structural stability, Part L sets the thermal performance targets for the new walls, roof, windows and doors and caps how much of the extension's floor area can be glazed, and Part H4 requires water company approval for any foundation within 3m of a public sewer. We decide the route with you at the design stage based on the specific job, not as a default answer.
Structural engineer sizes every steel beam and padstone before we price the job, catching problems Building Control would otherwise reject laterOne team runs the structural engineer, Building Control application and Party Wall Act 1996 process together rather than as three separate chasesWe advise Full Plans versus Building Notice based on your specific job's risk, not a default answerRegular coverage of Ealing and the wider West London area
Signs to look for
Do you need house extensions in Ealing?
You've outgrown a two- or three-bed Victorian/Edwardian terrace or ex-council flat, but moving in Zone 2-4 London would cost more in stamp duty and fees than extending the current property
You're relying on a side-return, alley or awkward rear garden as dead storage space rather than usable floor area
A growing or multi-generational household needs an extra bedroom or bathroom that a two-storey extension could add above a ground-floor extension
You've had conflicting advice about whether your project needs full planning permission, prior approval, or falls under permitted development, and nobody's checked your borough for an Article 4 Direction or conservation area status
How the work is handled in Ealing
Step 1Initial site visit and measured survey of the existing house, boundary lines, drainage runs and nearby trees, checked against permitted development limits and the borough's conservation area / Article 4 status
Step 2Design and route decision - permitted development, Larger Home Extension Scheme prior approval, or full planning permission
Step 3Structural engineer appointed to size steel beams, padstones and foundations and produce calculations for Building Control
Step 4Building Control application submitted - Full Plans (formal approval in 5-8 weeks) or Building Notice (start in 2 days, no prior sign-off) - decided on the specific job's structural and ground-condition risk
Step 5Party Wall etc. Act 1996 notices served on affected neighbours where a shared wall or nearby excavation applies, run in parallel with Building Control rather than after it
Step 6CCTV drainage survey and, where needed, a build-over agreement application to the water company before foundations are dug
Step 7Groundworks - trial pits, foundation excavation and pour sized to the actual ground conditions and agreed depth
Step 8Structural steel installed and the opening formed between the existing house and new extension, with temporary propping as needed
Step 9Superstructure built with particular attention to insulation continuity at the wall-to-roof and wall-to-existing-house junctions
Step 10Windows, doors and roof glazing fitted to current Part L standards, followed by first-fix electrics and plumbing
Step 11Building Control inspections at foundations, DPC/membrane, drainage and insulation stages, through to completion certificate
Step 12Second fix, decoration and snagging, confirming the new damp-proof membrane is properly lapped with the original house's DPC before ground levels are finished
Questions
House Extensions questions in Ealing
How quickly can Lian start rear, side-return, wraparound and two-storey house extensions with structural engineering and Party Wall compliance in Ealing?
Ealing is part of our regular West 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 Ealing?
Yes. Ealing falls within the area Lian Construction serves across Greater London.
How much notice do you need for a home extension or loft conversion in Ealing?
It varies with the size of the job and whether planning permission or building control sign-off is needed, which can add weeks to the timeline before work even starts. As a rough guide, it's sensible to get in touch a few months ahead if you're hoping to start at a particular time of year, so there's room for design, approvals and scheduling.
Is a two-storey extension cheaper per square metre than a single-storey one?
Often, yes - a two-storey side or rear extension typically costs roughly £2,800-£4,200/m², lower than a single-storey extension's £3,000-£5,000/m², because the foundation and roof, the two most expensive elements of any extension, are shared across double the floor area. Total project cost is still higher overall, commonly £120,000-£200,000+, but the cost per square metre of usable space is generally better value.
Do I need a structural engineer for my extension?
Yes, for any load-bearing opening or new foundation - a structural engineer sizes the steel beam or RSJ, specifies padstones and bearings, and designs the foundation to suit your ground conditions, producing the calculations Building Control requires for sign-off. Pricing a job off a guessed beam size instead of a calculated one is one of the most common reasons a knock-through opening gets rejected once Building Control inspects it, which then costs time and money to correct mid-build.
Why do you need a soil report or trial pits before pricing the foundation?
A trial pit and soil assessment tells the structural engineer what the foundation actually needs to bear on, which matters enormously on London clay because it shrinks and swells with moisture content, particularly near trees, hedges or where a tree has recently been removed. Skipping this step and defaulting to a standard strip foundation depth can mean the foundation is too shallow for the actual ground conditions, leading to cracking once nearby vegetation changes the soil's moisture balance, sometimes years after completion. It's a modest upfront cost compared to underpinning a foundation that's already failed.
Talk to Lian Construction about Ealing
Send the site address in Ealing, photos if available, and the house extensions work you need. We can review the scope and arrange the next step.