House extensions, loft conversions and refurbishments in London. One team, end to finish — from architect to painter. No handoffs between designer, structural engineer and builder.
Structural openings, steel beams, load-bearing walls — the engineering as much as the finish. From architect's drawing to final coat, one accountable team throughout. We work with a network of 120+ vetted trade specialists across London, and build the right team for your project.
Rear, side-return, wrap-around. More space, more light, added value.
Dormer, hip-to-gable, mansard. Turn dead roof space into a real floor.
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Structural work, joinery, plastering, decorating. Full renovations done properly.
Explore refurbishment →
Answer a few questions, get an indicative range. We confirm the real number on site.
Choose the service that best matches your project.
Estimate to the nearest half metre — we'll confirm exact dimensions on site.
Nothing here is locked in.
If you're not sure, we're glad to advise at your site visit.
This has the biggest effect on the final specification and price.
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Your phone number and email are required so we can send the full breakdown and follow up about a site visit.
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Thank you, —. We've noted your details against —. A member of Trinity will call within one working day to arrange a free, no-obligation site visit.
We handle design, planning and party wall agreements in-house. No gaps, no delays, no surprises on site.
“A good extension. It looks like it was always there.” Trinity — Design Principle
Same seven steps on every job. You always know what happens next.
You contact us and we talk through the project you have in mind, on-site or over a call.
We prepare a project proposal from your architectural drawings, or a bespoke design created in-house with our architects.
Once you're happy with the quote, we confirm scope, programme and payment structure in writing.
We liaise with building control and party wall surveyors to get every consent in place before work starts.
Trades booked and sequenced in advance. No delays, no downtime on site.
We manage every stage of the build from start to finish, against a bespoke project plan built for your home.
Final sign-off and certification from all relevant authorities, backed by our 10-year warranty.
Every project begins with how the space will be lived in, not just how it will look.
Skilled tradespeople, managed in-house, held to the same standard on every job.
Fixed price in writing, one named project manager, and a 10-year warranty behind every build.
Two decades converting lofts, extending homes and refurbishing properties across London. Every job gets a fixed-price agreement, a named project manager — Constantine Timotaru — and building control and party wall matters handled for you, not left for you to chase.
We carry full public liability insurance and back every build with a 10-year structural warranty. No subcontractor handoffs, no surprise invoices.
Everyone has the right to go home safely to their families every day. We hold our people, subcontractors and sites to that standard without exception.
10% deposit, then five further payments tied to completed milestones — foundations, structure, first fix, second fix, completion. You get dated photos of each finished stage before that payment is due, and we hold back the final 10% until snagging is signed off. You're never paying for work that hasn't happened yet.
Extensions, conversions and refurbishments across London. Full case studies on request.
Planning rules, costs and design — written to actually answer the question.
Permitted development limits, when you need full planning, and how party wall agreements fit in.
Read guide → CostsReal ranges by borough and finish level, and where the money actually goes.
Read guide → Loft ConversionsHeadroom, cost and planning differences between the main loft conversion types.
Read guide → Building RegsWhen you need one, how long it takes, and what happens if a neighbour objects.
Read guide → DesignA straight comparison for London terraces and semis.
Read guide → TimelineRealistic timelines from first drawing to final sign-off, stage by stage.
Read guide →Sample posts — connect a CMS or add real articles here.
“Every trade was managed for us — we never had to chase anyone. The extension finished on the date we were given at the start.”
Private Residence, Highgate“They handled building control and the party wall agreement without us lifting a finger. The finish is exactly what we asked for.”
Private Residence, Clapham“A genuinely design-led team — they suggested changes to the layout that made the whole extension work better than our original plan.”
Private Residence, ChiswickSample quotes — swap for real reviews.
Tell us about your project. We call back within one working day — same project manager from quote to completion.