Carry on with our Build Phase
Same team, no re-tender.
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Design
Phase
Design with us. Build with us, or take
the drawings to your own builder.
1,750+
London extensions
since 2007
since 2007
4.4
Google Reviews
Google Reviews
SW · SE · W · NW
Design Phase
Design with us. Build with us, or take the drawings to your own builder.
SUMMARY
Our Design Phase delivers planning-ready drawings, a Building Regs pack and structural calcs for a fixed fee from £3,995 +VAT. Eight to twelve weeks, depending on the scheme and the borough. Perpetual royalty-free right to use the drawings. Carry on with our Build Phase, or take the pack to a contractor of your choice. From the 1,750+ extensions we've designed and built in London since 2007.
What you walk
away with
- Architect-drawn planning and working drawings
- Planning consent — or a refusal report with appeal options
- Building Regulations pack (Approved Documents Part A, B, L)
- Structural engineer's calculations
- Schedule of works and outline specification
- A tender pack any builder you brief can price against
How the design
phase runs
01
Initial consultation
— free, 30min
02
Site survey and measured
Drawings.
03
Concept design
rounds
04
Detailed design
and spec
05
Planning submission under
GPDO 2015 or full planning
06
Building Regs
pack
07
Tender pack
ready
08
Handover or carry
on to Build
In a conservation area or an Article 4 zone (parts of Hackney, Camden, Westminster, Lambeth, Southwark), step 5 becomes a full planning application — adds four to eight weeks. Householder planning fee in England from 2025 is £528, payable to the council.
Fixed-fee
design bundles
Loft conversion — Ready to Build
from £2,995 +VAT
Ground floor extension — Ready to Build
from £3,995 +VAT
Ground floor & loft — Ready to Build
from £4,995 +VAT
Ground floor & first floor — Ready to Build
from £5,495 +VAT
What can go wrong &
how we handle it
"What if planning gets refused?"
If the council refuses, the fee covers a refusal report and a pre-application discussion with you on the next route. Under current rules, an amended application can usually be resubmitted within 12 months at no extra council fee. Most refusals are recoverable with a redesign, not a fatal blow.
"What if the design fee creeps up?"
It doesn't. The bundle fee is contracted up front. You only pay extra if you ask us to design something outside the bundle scope — for example, adding a basement on a project quoted as a ground floor extension. Drawing amendments are unlimited within the original scope prior to submission to planning
"What if I don't want to build with you afterwards?"
You take the pack and brief your own builder. We hand over the drawings and the tender pack and that is the end of our involvement, with no claw-back fee. The design fee is independent of the build commitment.
Design with us.
Build with us, or tender
to other contractors.
Most London design & build firms ask you to commit to both phases upfront. We don't. Complete the design with us, then decide.
Take the drawings elsewhere
You own them. Here's what you'll need to brief your own builder properly.
→ Read the handover guideRecent design projects
Design Phase FAQ
Do I need planning permission for an extension in London?
Extensions in London can generally be built under Permitted Development or Full Planning Permission. When we have understood your requirements and assessed the proposed plans against the local planning framework, we will advise you which planning route will serve you best. For schemes that can be built under Permitted Development, we always recommend that a Certificate of Lawful Development is sought prior to works commencing on site — and as part of our fixed fee design service we will prepare and submit this application on your behalf.
How much does an architect cost for a London extension in 2026?
Architects in London typically charge between 10-12% of the build cost for their services. At Build Team, all our design fees are fixed-fee basis. Our Ready to Build design packages start from £2,995 +VAT for loft conversions and £3,995 +VAT for ground floor extensions. The design phase from Build Team includes everything you need to build — plans, technical drawings and full structural engineering.
What's the difference between permitted development and full planning?
Certain types of extension projects are automatically allowed under national planning rules, and you do not require a formal planning application, however we still recommend obtaining a Lawful Development Certificate from the Council. If the extension is larger or exceeds the permitted development limits, then a full planning application will need to be submitted to the Council. Our in-house Architects will advise and submit the relevant application for your scheme.
How long does planning permission take in London?
Typically, 6-8 weeks from date of validation through to determination.
Is the design fee really fixed, with no extras?
Yes, our packaged design fees are fully fixed for the scope outlined within our fee proposal. Some projects may require a Party Wall Award and / or a Build Over Agreement and this is something we will be able to advise following the Design Consultation and you can choose to bolt-on these services should you wish.
Do I own the drawings if I don't build with you?
Yes, we will issue a design completion pack at the end of the design phase with all the necessary drawings for a Contractor to build from. From a contractual perspective, whilst we retain ownership of the underlying intellectual property, we issue all clients with a royalty-free, perpetual licence to use our drawings as they so wish.
Does the design fee come off my build cost?
No - this is a separate service and is priced separately. Design and Build clients have the option to fix their build costs up front — which will be presented alongside our fixed-fee design service.
What happens if planning is refused?
We will review the reasons for refusal on your behalf and present you the options you have available. These may include a resubmission of the original planning application with amendments or submit a formal appeal.
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