Part single, part two-storey extensions in Waltham Abbey

Useful details for planning a part single, part two-storey extension in Waltham Abbey.

Postcode districts: EN9
County / area: Essex, England
Price region: East of England
Guide price: £74,000–£102,000 (£2,060–£2,830 per m²)
Approval route: It may be permitted development if it goes no more than 3 m beyond the original rear wall (counting any single-storey part) and stays 7 m from the rear boundary; otherwise it needs planning permission.
Nearest towns: Waltham Cross (1.4 miles), Cheshunt (1.4 miles), Enfield Lock (1.5 miles)
Distance to Southend-on-Sea: about 32.5 miles
First visit: Free, no obligation

About a part single, part two-storey extension

A part single, part two-storey extension is an extension where the ground floor is wider or deeper than the floor above, so only part of it rises to two storeys. It usually gives a large kitchen or living area with roof lights below and one bedroom or bathroom above. It is often a good way to add space while limiting the effect on neighbours.

We cover postcode district EN9 in and around Waltham Abbey, along with neighbouring Waltham Cross, Cheshunt and Enfield Lock.

What it costs in Waltham Abbey

Most of the cost of a part single, part two-storey extension is set by its size and specification. For Waltham Abbey and the rest of the East of England, our guide is £2,060–£2,830 per m² including VAT, so about £74,000–£102,000 for a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total). The fastest way to a firmer number is a free site visit, after which we price the design stage in writing.

Spec	Per m²	A 6 m × 4 m ground floor and a first floor over half of it (36 m² in total)
Essential	£1,900–£2,610 per m²	£68,000–£94,000
Standard	£2,060–£2,830 per m²	£74,000–£102,000
Premium	£2,470–£3,400 per m²	£89,000–£122,500

Planning and building regulations in Waltham Abbey

In England, the extension can only be permitted development if it goes no more than 3 m beyond the original rear wall and stays at least 7 m from the rear boundary, with matching materials and roof pitch. We check the whole design against the rules, including the 50% garden coverage limit. If any part fails, or extends beyond a side wall on two floors, you need planning permission, costing £548 (or £575 for applications made from 8 December 2026).

Approval in England: Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.

Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.

Design points for Waltham Abbey homes

Light into the kitchen

The single-storey part is the place for roof lights or a lantern, which bring daylight deep into the plan. In England, glazing is normally limited to 25% of the new floor area plus any windows removed, unless calculations show the house still performs, so we plan the balance early.

Structure at the step

The first-floor wall above often sits over the new open-plan space, so it needs a steel beam or frame to carry it. Loads come down at different points than in a full two-storey design, and the engineer sizes the foundations to suit each part.

How we'd run your project

Understand the brief
At your home in Waltham Abbey we agree what you need: bedroom count, bathroom, kitchen space, and how much garden you want to keep.
Drawings and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering Waltham Abbey.
Price it properly
Once the engineer's calculations are in, we fix the build price in writing, with a clear list of what's included.
Build it
The new structure goes up first, then we open into the house, finish inside and get the completion certificate.

Questions about part single, part two-storey extensions in Waltham Abbey

Which postcodes do you cover around Waltham Abbey?

We cover Waltham Abbey (EN9) and nearby places including Waltham Cross, Cheshunt and Enfield Lock, plus the rest of Essex. The first site visit is free.

How much does a part single, part two-storey extension cost in Waltham Abbey?

Our guide for the East of England, which covers Waltham Abbey, is £2,060–£2,830 per m² including VAT. A typical project with a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total) comes to about £74,000–£102,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

How long does a part single, part two-storey extension take?

Allow 4 to 8 weeks for survey and design, then the approval period (councils should decide householder applications within 8 weeks of validation), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.

Can the single-storey part be deeper than the two-storey part?

With planning permission, yes, and that is often the point of the design: the ground floor projects further into the garden while the first floor stays back from neighbours. Under permitted development, the depth limits for extensions of more than one storey can apply to the whole extension, so we confirm which route applies before drawings are finalised.

Can I add roof lights to the single-storey part?

Yes. Roof lights or a lantern over the single-storey part are one of the main reasons to choose this design, as they light the middle of a deep kitchen. In England they count towards the Part L glazing allowance, normally 25% of the new floor area plus windows removed, so we balance them with the rear doors.

Nearby

We also cover places near Waltham Abbey, including:

Other extensions in Waltham Abbey

All two-storey extension services in Waltham Abbey · Part single, part two-storey extensions across Essex

Book a free site visit in Waltham Abbey and we'll tell you what's possible, what approvals you need and what the design stage would cost.