Large Single-Storey Extension and Loft Conversion in Shenfield

Large Single-Storey Extension and Loft Conversion in Shenfield, Brentwood

We designed and managed a large single-storey rear extension and loft conversion for a detached property in Shenfield, Brentwood, Essex.

Project Overview

The project centres on a rear extension with a modern double-gabled roof, plus a loft conversion adding a new double bedroom. We handled the architectural design, planning permission, structural engineering, and building regulations from the first sketch through to construction.

A Project That Came Through Recommendation

This one came about because of a neighbour a few doors down, whose own project we’d worked on previously, a job that combined a single-storey extension, a double-storey extension, and a rear dormer all at once. Seeing that finished was apparently enough to convince the family here to give us a call.

We really value this kind of recommendation. A significant amount of our work comes from previous clients and completed projects nearby, and it’s always a good sign when a homeowner has seen a neighbour’s finished project and wants something similarly well thought through for their own home.

A Naturally Light Single-Storey Extension

Natural light was the priority behind every major design decision on this project. The roof itself does a lot of the work here: we chose a double-gabled shape and set two glazed sections into it, sitting directly over the sliding doors below. It gives the whole rear elevation a confidently modern look while pulling far more daylight into the room than a standard roofline ever could.

Below the gables, four aluminium sliding panels run floor to ceiling, so the new kitchen, dining, and living space opens straight onto the garden rather than being separated from it by a wall of brick. Six roof windows are worked into the design too, each one positioned to reach the parts of the extension furthest from the doors. Between the roof windows, the glazed gables, and the full-height sliding glass, there’s genuinely nowhere in the room that feels dim, whatever time of day it is.

Project Highlights

A closer look at the key features, finishes and practical improvements that bring the completed space together.

Open-Plan Kitchen, Dining and Living Space

Before the extension went up, the kitchen, dining, and sitting areas at the back of the house were all fairly boxed off from one another. Knocking that layout together was the whole point of the project; the family wanted one room they could actually live in together, not three small ones they kept drifting between.

The new kitchen sits around a large island, which has quickly become where most of the actual living happens: homework, breakfast, people gathering while dinner's on. A single wood floor was laid across the whole footprint, so there's no visual break between where the kitchen ends and the dining or living zones begin. With the sliding doors open, that same floor effectively continues out onto the patio, which is exactly the connection the family wanted between the new room and the garden.

The Bootility Room

One of the most practical parts of the design is what the client calls the bootility room, a combined boot room and utility space, tucked off to one side and reached through its own separate door rather than through the kitchen. Anyone coming in from the garden lands there first, so wet coats, dirty trainers, and the general clutter of family life never actually make it as far as the new open-plan space.

It's not the part of the house anyone shows off first, and it was never meant to be. But it's the sort of room that ends up mattering more than the design brief ever suggested it would, long after the excitement of the new kitchen has settled down.

Loft Conversion and Bespoke Bedroom

Upstairs, the loft became a large double bedroom, a straightforward brief on paper, but the clients wanted one thing a standard loft conversion doesn't usually offer: a freestanding bathtub, sitting openly within the bedroom itself rather than tucked behind an en-suite door. It's a design choice that came up early in the process and stayed in every version of the drawings after that.

Together, the new bedroom and the ground-floor extension have significantly increased the usable space in the property, without the clients needing to move house to get it.

Planning Permission in Shenfield and Brentwood

Shenfield falls under Brentwood Borough Council for planning purposes, so that’s where this application went. Given the scale of what was being proposed- a large extension plus a loft conversion- this was never going to be a permitted development project. A full planning application was the only route available.

We put the drawings together and ran the whole application on the clients’ behalf, from the first design sketch through to the decision letter. Once that decision came back approved, the project could move into the technical drawings needed for building control and, eventually, onto site. For anyone else in Shenfield weighing up a similar project, getting a proper read on the planning position before committing to a design is time well spent.

Building Regulations and Structural Engineering

Once the architectural and planning work was complete, we moved on to building regulations and structural engineering, a genuinely separate stage, and one first-time clients often assume is already covered once planning’s been granted. It isn’t. Planning is really a judgement call on whether the development belongs where it’s proposed; building regulations are about whether it’s actually put together safely and correctly once work starts.

Brentwood’s building control team checked the work against the Building Regulations as it progressed, inspecting the build at each of the key stages. On our side, we’d already produced the technical drawings and structural calculations they needed to do that job properly, and the approval that followed was granted without a single amendment requested.

Services Provided

We provided the full design service for this project, including:

Architectural plans and design
Planning permission
Building regulation drawings
Structural engineering
Building regulation approval
Support through the process from design through to construction

Design took roughly two weeks from start to finish. Structural engineering and building regulations added another two weeks on top of that. Once everything was signed off, we helped the clients find a reliable, vetted builder to actually carry out the construction.

Project Costs

The professional fees for this project were:

Service	Cost
Architectural plans	£2,095
Building regulations	£1,995
Structural engineering	£2,495
Total professional fees (inc. VAT)	£6,585
Build cost	Approx. £175,000 + VAT

On top of the professional fees, the construction itself- the extension, the loft conversion, and the wider internal changes to the house- came in at roughly £175,000 plus VAT.

Considering a House Extension in Shenfield or Brentwood?

Got something similar in mind for your own home in Shenfield or Brentwood- an extension, a loft, or a bit of both? We’d talk you through the design work, sort the planning side of things, cover the structural engineering and building regs, then put you in touch with a builder we trust once it’s all signed off. A free Discovery Call is the easiest place to start.

Frequently asked questions

How much does a house extension cost in Shenfield?

For this Shenfield project, total professional fees (architectural plans, building regulations, and structural engineering) came to £6,585 including VAT, and the build cost was approximately £175,000 plus VAT for a large single-storey extension, loft conversion, and internal alterations. Costs vary by project size and specification; we provide a realistic estimate for your own property during a free Discovery Call.

Do I need planning permission for an extension in Shenfield?

It depends on the scale of the project. For this Shenfield extension and loft conversion, the size of the works meant a full planning application was required rather than the project falling under permitted development. Planning permission was granted the first time. We assess the correct route for every project before any design work begins.

Who is the planning authority for Shenfield?

Brentwood Borough Council is the local planning authority responsible for Shenfield. All planning applications and building control matters for properties in Shenfield are handled through Brentwood Borough Council, including householder extensions, loft conversions, and alterations.

How long does a house extension take in Brentwood?

On this Shenfield project, design took around two weeks, with structural engineering and building regulations adding roughly two more weeks on top. Both the planning application and the building regulations approval went through without needing amendments. Timelines shift depending on project size and how straightforward the planning application turns out to be.

Project Summary

Project	Shenfield, Brentwood, Essex
Local authority	Brentwood Borough Council
Property	Detached house
Works	Large single-storey rear extension + loft conversion + internal alterations
Design	Modern double-gabled extension with extensive glazing
Architectural process	Approximately 2 weeks
Structural engineering & building regulations	Approximately 2 weeks
Planning approval	First time
Building regulations approval	First time
Professional fees	£6,585 including VAT
Build cost	Approximately £175,000 + VAT

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