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.
Newham overview
House Extensions in Newham
Stratford regeneration continues to drive refurbishment and repair demand across converted and new-build stock alike. Newham falls well within the East 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 Newham, that local knowledge means fewer surprises once work is on site and a team that already understands the borough's typical property stock.
Newham's housing stock is a mix of eras rather than one dominant type. Older neighbourhoods away from the Stratford core still have Victorian and Edwardian terraces, along with inter-war and post-war housing, much of it converted into flats over the decades. Around Stratford itself, the picture is different: large-scale new-build apartment blocks have gone up since the Olympic regeneration began, alongside conversions of older industrial and commercial buildings into residential use. This mix means work in the borough spans everything from traditional repair and repointing on period terraces to snagging and remedial work on newer builds, plus the specific issues that come with converting non-residential buildings into homes. For a contractor, this variety matters: a Victorian terrace and a five-year-old conversion flat fail in different ways and need different approaches. Owners and landlords in Newham are as likely to be dealing with settlement cracks in a new block as damp in an old one, so it helps to work with a contractor who isn't only set up for one type of property.
The continued regeneration around Stratford has kept refurbishment and repair demand high across Newham, and that demand isn't limited to new-build. Converted properties, some created during earlier waves of development, are now old enough to need attention themselves, while newer stock often surfaces defects and snagging issues in the first few years. For homeowners and landlords, this means the borough has a steady flow of work but also a busy trade, and finding a contractor with availability can take longer than in quieter areas. Landlords managing flats in converted or new-build blocks tend to deal with a narrower set of recurring issues, plasterwork, minor leaks, finishing snags, while owner-occupiers in older terraces further from the centre are more likely to need broader repair or refurbishment work. Given how much building activity the regeneration has brought to the area, it's worth getting quotes early and being clear about timescales, since demand can affect how quickly work gets scheduled. Property type also affects who you need: not every firm working in Newham is equally comfortable across period terraces and modern conversions.
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 Newham and the wider East London area
Signs to look for
Do you need house extensions in Newham?
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
A previous quote priced the job without mentioning a structural engineer, a soil or trial pit assessment, or a Party Wall Act process - on a terraced or semi-detached house that usually means the price is wrong or incomplete
There's visible evidence of a botched earlier extension on the property - a cold stripe of mould along a roof-to-wall junction, a damp patch where a patio's built up against the original wall - and you need it diagnosed and corrected as part of any new work
How the work is handled in Newham
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 Newham
How quickly can Lian start rear, side-return, wraparound and two-storey house extensions with structural engineering and Party Wall compliance in Newham?
Newham is part of our regular 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 Newham?
Yes. Newham falls within the area Lian Construction serves across Greater London.
Is it harder to book a contractor in Newham because of all the regeneration work going on?
It can be, particularly for firms already stretched by the volume of activity in and around Stratford. We'd suggest getting quotes and lining up work earlier than you might elsewhere, especially if your job isn't urgent. It's also worth checking a contractor can actually take on the work in your timeframe before committing, rather than assuming availability.
What if my extension is close to a public sewer or drain?
Building Regulations Part H4 requires a build-over agreement from the water company (usually Thames Water in London) if your foundation footprint is within 3m of a public sewer or 1m of a public lateral drain, separate from your Building Control approval. Many Victorian and Edwardian terraces have drain runs under the rear garden that aren't obvious from the surface, so we commission a CCTV drainage survey at the design stage to catch this before foundations are priced, not after excavation starts - discovering a clash mid-dig usually means redesigning the foundation or diverting the drain partway through the job.
What causes damp or mould in a new extension after it's built?
The two most common causes both show up after handover: cold bridging at the junction where the new roof or wall meets the original house, which appears as mould or condensation along the junction after the first winter if insulation continuity wasn't maintained through the detail, and a bridged damp-proof course, where the new floor slab or render against the original wall isn't lapped correctly with the existing DPC, letting damp track up internally regardless of how well the rest of the build was done.
How much does forming the structural opening between the house and extension cost?
A structural opening with an RSJ steel beam typically costs £1,800-£4,500+ on top of the extension build itself, depending on the span, whether padstones or additional support are needed, and the condition of the existing wall once opened up. This is priced separately from the extension shell because it depends on structural engineer calculations specific to your wall, not a standard rate - jobs priced against a guessed beam size often need reworking once Building Control reviews the calculations, which costs more than getting it right the first time.
Talk to Lian Construction about Newham
Send the site address in Newham, photos if available, and the house extensions work you need. We can review the scope and arrange the next step.