Extension plans and drawings in Portishead
We prepare extension plans and drawings for homes in Portishead, as a stand-alone service or as the first stage of a design and build project.
- Guide price in PortisheadFrom £1,200 inc VAT
- PlanningWe find the right route for you
- Timescale2–6 weeks for drawings
- Postcode districtsBS20
Working in Portishead
Postcode districts we cover around Portishead include BS20. We also work in nearby Nailsea (3 miles), Clevedon (5 miles), Keynsham (13 miles), Weston-super-Mare (13 miles).
Kingswood, in Gloucestershire, is roughly 11 miles from Portishead and also on our list. South West homes range from terraced streets in the cities to stone cottages and bungalows in the countryside, and conservation areas are common in historic centres.
Fees in Portishead
Guide fees for Portishead including VAT, using our South West England factor of ×1.02. Council and building control charges are not included.
| Option | What it covers | Guide price |
|---|---|---|
| Essential | Measured survey and planning drawings | £1,200 – £2,250 |
| Standard | Planning drawings plus building regulations drawings | £2,200 – £3,900 |
| Premium | Full pack with structural calculations and 3D visuals | £3,450 – £5,650 |
Try the guide-price tool to see a range for your own size and finish.
What is included
- 3D views to check the look and the light (full pack)
- Measured survey of the house and garden
- Planning drawings: existing and proposed plans and elevations, site and location plans
- Structural calculations from an engineer (full pack)
- Two or three layout options to compare
- Building regulations drawings and specification
Will the council need to approve it?
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.
In a conservation area, national park, National Landscape, the Broads or a World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
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.
Building over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
Applications are decided by the local planning authority (your district, borough or unitary council).
What happens next
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
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
Fixed written price
We confirm the build price in writing, based on the approved drawings and the finishes you have chosen.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Questions answered
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Portishead, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Who do I contract with in Portishead?
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.
Will my neighbours in Portishead be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
How much do extension plans cost?
Our design packs range from about £1,200 to £5,650 including VAT, from planning drawings only to a full pack with building regulations drawings, structural calculations and 3D views. Council fees are separate.
Can I use your drawings with another builder?
Yes. Once paid for, the drawings are yours to use for your project.
Book a free site visit in Portishead
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.