Loft Conversions
Turning the space under your roof into a bedroom, bathroom or study — designed so the new floor feels like it was always part of the house.
- Feasibility study
- Structural calculations
- Building control drawings
- Party wall notices
Our Services
Four services.
One seamless process.
Every stage of your build.
From the first sketch to the final sign-off, everything under one roof — loft conversions, rear extensions, planning permission and Principal Designer support. No juggling contractors. No gaps between stages. Just a clear path from idea to finished home.
Our Services
Four services · One continuous process
What we do
Four services,
one seamless journey.
From the first measured survey to the final building-control sign-off — everything under one roof. One point of contact. One fixed fee. No handoffs. No surprises.
Whether you need one service or all four, the standard is the same — drawings clear enough for a builder to work from, drawings clear enough for a council to approve.
Rear Extensions
Opening the back of the house to the garden — full-width glazing, side-return, wrap-around or two-storey, engineered for light.
- Measured survey
- Concept & materials
- Structural openings
- Threshold details at 1:5
Planning Permission
Full applications, lawful development certificates and prior approval notices — prepared, submitted and managed through to the decision.
- Planning & site drawings
- Design & access statement
- Council submission
- Discharge of conditions
Principal Designer
CDM 2015 Principal Designer duties for domestic projects — health and safety coordination from pre-construction to completion.
- Pre-construction information
- Construction phase plan
- Site visits & coordination
- H&S file on completion
Not sure which you need?
Tell us about the project — we'll tell you honestly which services apply, and which you can skip.
How We Work
From first call to keys in hand.
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The first call
You tell us about your house. We listen more than we talk. Forty minutes later, you know what's possible.
Free · Week 1 -
The first sketch
You see your house on paper for the first time. Two or three layouts, tested against how you actually live.
Weeks 2–5 -
The waiting
The council has your drawings. We handle the back-and-forth. You get on with your life.
Weeks 6–14 -
The full set
Every detail drawn. Every question answered before your builder thinks to ask it. Nothing improvised on site.
Weeks 8–16 -
The first day on site
You meet your builder. Work begins. Whenever a question comes up — it's already in the drawings.
Build starts
Same five moments every project — a loft, an extension, or the whole back of the house. The only thing that changes is the house.
Start with a conversationWhat You Receive
Every project, drawn in full.
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01
Measured survey
Week 1A two-hour visit to your home. Every wall, door, window and level noted and drawn to scale.
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02
Existing plans
Week 2Accurate as-built drawings of the house you actually own — the baseline every design decision sits on.
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03
Concept layouts
Weeks 3–5Two or three schemes for how the space could work. Tested against how you live — not just how the room is shaped.
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04
3D visuals
Weeks 5–6Axonometric or interior renders of the chosen scheme, so you see the space before a brick is laid.
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05
Planning application pack
Week 6Site plan, elevation drawings, design and access statement — the full submission, prepared in our hands.
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06
Structural coordination
Weeks 8–10A structural engineer appointed by us, coordinated with the drawings so the openings work before they're built.
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07
Building control drawings
Weeks 10–12The compliance set — insulation values, structural notes, means of escape. Everything your inspector needs to sign off.
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08
Construction details at 1:5
Weeks 12–14Thresholds, roof junctions, lintels and party walls — drawn at the scale your builder actually works at.
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09
Site support throughout
Build durationSite queries answered, details clarified, health and safety coordinated — from first day to final sign-off.
All nine, every project — no hidden extras, no surprise invoices. Just a complete file, drawn for the people who'll build it.
Book a Free ConsultationCommissioning Us
No packages. No tiers.
Just a scope that fits the project.
We don't sell fixed plans. Every commission is shaped after the first conversation — around what your project actually needs, not a menu we've pre-written. Some clients want the drawings only; others want us on site until the last nail. Both are fine.
What you want to manage
Some clients bring their own builder and run the build. Others hand the whole thing to us. Both work — we scope accordingly.
What planning requires
Whether permission is needed, and how involved the application is, changes what we prepare and how long it takes.
What the structure asks
A rear window sits very differently to a two-storey extension. Openings, load paths and party walls all shift the scope.
How long we stay
Drawings only, drawings through to approval, or drawings to the end of the build. Entirely your call — and priced on that basis.
Tell us about the project — we'll tell you honestly which shape it takes, and what that costs.
Book a Free ConsultationQuestions, Answered
The things homeowners
ask us first.
Straight answers to the questions we hear most — planning, cost, timelines and everything in between. 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. Single-storey rear extensions can often go up to 3–6 metres depending on your property type.
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. 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 fixed and quoted upfront — typically £2,500–£5,500 depending on scope, covering measured survey, concept design, planning drawings and the planning submission.
Build costs are separate and paid directly to your contractor. As a rough London guide, expect £2,400–£3,200 per m² for a rear extension and £45,000–£75,000 for a typical loft conversion. We'll give you a realistic range once we've seen the property.
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. They're separate approvals, checked by a Building Control body, and 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.
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. 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. 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.
