Extension plans and drawings across Harrow
Need extension plans and drawings in Harrow? We survey the house, prepare what the council needs and deal with the officers until a decision is made.
- Guide price in HarrowFrom £1,550 inc VAT
- PlanningWe find the right route for you
- Timescale2–6 weeks for drawings
- Postcode districtsHA0, HA1, HA2, HA3, HA7
Working in Harrow
Our survey diary covers Harrow, including HA0, HA1, HA2, HA3, HA7, HA9. The same team covers Wealdstone (1 mile), Wembley (2 miles), Pinner (2 miles), Northolt (3 miles), all within easy reach.
London's housing is dominated by Victorian and Edwardian terraces, many with a rear outrigger and a side return, and 1930s semis in the outer boroughs. Conservation areas are common, so the planning check comes first.
Who this service is for
- Projects that need a planning application or other approval
- Homeowners at the very start of a project
- Anyone who wants fixed designs before getting build prices
Do I need planning permission in Harrow?
In England the main routes are permitted development (ideally confirmed with a lawful development certificate, £274), larger home extension prior approval (£249, 42 days) and a householder planning application (£548, normally 8 weeks), with council fees as set from 1 April 2026.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
If the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations.
Applications are decided by the local planning authority (your district, borough or unitary council).
Design and approval fees for Harrow
Guide fees for Harrow including VAT, using our London factor of ×1.3. Council and building control charges are not included.
| Option | What it covers | Guide price |
|---|---|---|
| Essential | Measured survey and planning drawings | £1,550 – £2,900 |
| Standard | Planning drawings plus building regulations drawings | £2,850 – £4,950 |
| Premium | Full pack with structural calculations and 3D visuals | £4,400 – £7,150 |
Try the guide-price tool to see a range for your own size and finish.
Our process, step by step
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
We visit your Harrow home, measure up, talk through what you want and check the planning position.
Design and approvals
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
The build is managed from start to finish, inspected at each stage and signed off on completion.
Questions answered
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Harrow, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Do I need building regulations approval in Harrow?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Who do I contract with in Harrow?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
Can I use your drawings with another builder?
Yes. Once paid for, the drawings are yours to use for your project.
Do I need an architect?
Not necessarily. For most extensions an experienced designer or architectural technologist is enough. For listed buildings or complex sites an architect’s input can help.
Book a free site visit in Harrow
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.