Harrow · London · North West London
House Extension & Loft Conversion
Architectural Designers in London & Harrow
Firstly, we are a Harrow-based architectural design studio specialising in house extensions, loft conversions, and planning permission. Additionally, our team provides full principal designer support across London and North West London.
- Experienced Architectural Designers
- Fixed-fee proposals
- Free consultation
What We Do
Four services,
one seamless journey.
Firstly, every project runs under one roof — with one point of contact and one fixed fee. Additionally, we handle everything from the first measured survey to the final building-control sign-off. No handoffs, no surprises.
Rear Extensions
For example, our house extension architectural designers design light-filled kitchens, garden rooms and open-plan living spaces. Consequently, every extension respects both your home's character and Harrow Council's planning policies.
Explore serviceLoft Conversions
Furthermore, whether you need a dormer, hip-to-gable, mansard or rooflight conversion, we turn unused roof space into a bedroom, study or master suite — without losing head height.
Explore servicePlanning Permission
Moreover, we prepare drawings, forms, council liaison and appeals. As a result, we know exactly what Harrow Council expects — and how to secure planning permission without wasted months.
Explore servicePrincipal Designer
Ultimately, our CDM 2015 compliance, risk management and construction-phase oversight keep your project safe, legal and on programme. In other words, we look after every detail from start to finish.
Explore serviceHowever, if you're not sure which service you need, simply tell us about the house — we'll tell you what's possible.
Book a Free Consultation
The Studio
A Harrow studio,
built on local knowledge.
We are a Harrow-based architectural design studio offering four core services — rear extensions, loft conversions, planning permission and Principal Designer support. Every project begins with listening: how do you want to live, and what is the site telling us?
From there we handle everything — measured surveys, planning drawings, structural coordination and construction oversight. Highly experienced, deeply familiar with Harrow Council's planning policies, and trusted by homeowners across London and North West London.
- Experienced Architectural Designers
- Local planning expertise
- Fixed-fee proposals
- End-to-end support
Selected Work
Recent projects,
quietly transformed.
For instance, here is a snapshot of what we've delivered across Harrow and North West London — rear extensions, loft conversions and full-house refurbishments. Every project is planning approved, built beautifully, and lived in daily.
View all projects
How We Work
Five steps,
one clear journey.
From the first phone call to the final sign-off, you always know exactly where your project stands — what's happening now, what's next, and what it costs. However, there is no jargon, no black boxes, and no surprises.
Discovery & Feasibility
First, we hold a free consultation — either by phone or on site. We listen to how you want to live, review your property's constraints, and give you an honest view of what's achievable.
Week 1
Measured Survey
Next, we visit your home and record every dimension, level and boundary. This is the foundation every drawing is built on — accuracy now saves weeks later.
Week 2
Concept Design
Meanwhile, we prepare sketch layouts, 3D visuals and material palettes. We present two or three options, then refine the one you love — until it feels exactly right.
Weeks 3–6
Planning & Approvals
Subsequently, we handle the full planning application, including drawings, forms and council liaison. We manage the submission and respond to any queries through to approval.
Weeks 7–18
Technical Design & Build
Finally, we manage building regulations, structural coordination and construction oversight. We stay involved on site until the last snag is closed — and the keys are yours.
Weeks 19–40
Ready to start step one? The first conversation is free — and there's no obligation.
Book a Free ConsultationWhat Clients Say
Trusted by homeowners
across North West London.
Most of our work comes from people who heard about us from a neighbour, a friend, or a builder we've worked with for years. As a result, we've built a reputation for honest advice across Harrow and North West London. Here's what a few of them had to say.
Questions, Answered
The things homeowners
ask us first.
Straight answers to the questions we hear most — planning, cost, timelines and everything in between. However, if yours isn't here, the team is one call away.
Do I need planning permission for a rear extension?
Many rear extensions fall under Permitted Development — meaning no formal planning application is needed, provided they meet the rules on depth, height, materials and proximity to boundaries. Generally, single-storey rear extensions can go up to 3–6 metres depending on your property type.
However, if your plans exceed those limits, or your property is in a conservation area, listed, or has had previous extensions, you'll need a full householder application. We check this during the free consultation and tell you honestly which route applies.
How long does planning permission take?
Harrow Council's statutory determination period is 8 weeks for householder applications. In practice, most of ours are decided within 6–10 weeks from submission.
Before submission, allow 3–5 weeks for us to prepare the drawings, forms and supporting documents. Additionally, if a pre-application enquiry is worthwhile — usually for more complex or borderline schemes — add another 4–6 weeks for the council's response.
How much does a rear extension or loft conversion cost?
Our design fees are confirmed in a fixed-fee proposal once we've seen your property — agreed in writing before any work starts. It covers the measured survey, concept design, planning drawings and the planning submission.
Build costs are separate and paid directly to your contractor. They depend on the size, structure and finish you choose, so rather than publish a generic range, we'll give you a realistic estimate for your specific property once we've seen it.
What's the difference between planning permission and building regulations?
Planning permission is about whether you're allowed to build it — how it affects neighbours, the street scene and the local area. It's granted by the council's planning department.
Building Regulations are about how it's built — structural safety, fire resistance, insulation, drainage, ventilation. These are separate approvals, checked by a Building Control body. Furthermore, they are required regardless of whether planning permission is needed.
Do you manage the build, or just provide the drawings?
Our core service is design and planning — measured survey, drawings, planning submission and building regulations. Most clients then appoint a contractor directly.
If you'd like us to stay involved through construction, we offer Principal Designer support under CDM 2015 — reviewing the site, coordinating risk and checking the work matches the drawings. It's optional, but recommended for larger or more complex projects.
Which areas do you cover?
We're based in Harrow and work across North West London — including Pinner, Stanmore, Northwood, Kenton, Wealdstone, Ruislip, Wembley and Edgware.
Meanwhile, we also take on selected projects in surrounding boroughs. If you're outside our usual radius, get in touch — for the right project we'll travel.
Do I need a Principal Designer under CDM 2015?
CDM 2015 applies to any project with more than one contractor — which includes almost every domestic extension and loft conversion. The role of Principal Designer was introduced to make sure design-stage risks are identified, managed and handed over cleanly to the builder.
For a domestic client, the duties usually fall to the principal contractor if you don't appoint a Principal Designer in writing. Consequently, we offer this role directly and can take it on from the first conversation.
How do I get started?
Book a free consultation — by phone or on site. We'll ask a few questions about the property, what you're hoping to do, and roughly what budget you have in mind. Ultimately, you'll leave the call with a clear view of what's achievable and what it's likely to cost.
If you'd like to proceed, we'll send a fixed-fee proposal in writing within 2 working days. Nothing is billable until you approve it.