Do I need an architect for a house extension in London?

While it's not a legal requirement, working with a qualified architectural designer ensures your project meets building regulations, maximises your planning approval chances, and avoids costly mistakes.

How much does it cost to hire an architect in London?

A simple rear extension design starts from £800 + VAT. Double storey extensions from £1,000 + VAT. Loft conversions from £800 + VAT. Salstan offers free consultations and fixed-fee quotes.

How long does the architectural design process take?

A typical residential project takes around 4 weeks from initial consultation to planning submission. Planning decisions usually take 8 weeks for householder applications. Technical drawings take an additional 5-7 working days after planning approval.

Do you offer a design and build service?

Yes. Salstan is a full-service, turnkey practice. We manage projects from initial concept through to completed construction, including architecture, structural engineering, and building works - all under one roof.

What areas of London do you cover?

We cover all 33 London boroughs from our offices in Park Royal and Teddington. We also work across Hertfordshire, Surrey, Essex, Kent, and other Home Counties.

Can you help if my planning application has been refused?

Yes. We regularly help clients who have received planning refusals. We review the council's reasons for refusal, redesign the scheme to address their concerns, and resubmit or lodge a formal planning appeal where appropriate.

Flat Amalgamation · Wraparound Extension · Mansard Loft

Kensal Rise House Amalgamation, Wraparound Extension & Mansard Loft

Kensal Rise, North West London

Location

Kensal Rise, North West London

Property

Victorian mid-terrace house

Project type

Amalgamation of two flats, rear wraparound extension and L-shaped mansard loft dormer

Planning

Approved first time, Hammersmith & Fulham

The House and the Brief

This Victorian mid-terrace house in Kensal Rise had been divided into two one-bedroom flats, both in very poor condition. The kitchen and bathroom were worn out, the floors were stripped back to boards and screed, and the rooms had been cut up to suit two separate homes on a road made up mostly of family houses.

Our client wanted to return the building to a single family dwelling, and to make it a generous one. The brief was to combine the two flats into one house, add a rear wraparound extension and an L-shaped loft dormer extension, and give every floor the space and head height a modern family home needs.

Planning Permission for the Amalgamation

Turning two flats back into one house needs planning permission, and councils look closely at any proposal that reduces the number of homes. We prepared a single amalgamation application that covered the change back to one dwelling together with the rear wraparound extension and the L-shaped mansard loft dormer, so the council could assess the whole scheme at once.

The case rested on the street itself. The road is made up predominantly of single family dwellings, the existing flats were small and in very poor condition, and the amalgamation would create a high-quality family home of the kind the area is short of. Hammersmith & Fulham Council granted planning permission at the first submission.

Before & After

As We Found It

Drag across each image to compare the house before and after the works.

Front of the house in Kensal Rise after the works — Front elevation

Front of the house in Kensal Rise before the works — Front elevation

Rear of the house in Kensal Rise after the works — Rear and garden

Rear of the house in Kensal Rise before the works — Rear and garden

Front reception room after the works — Front reception

Front reception room before the works — Front reception

Kitchen in the new wraparound extension after the works — Kitchen

Original kitchen before the works — Kitchen

First-floor front bedroom after the works — Front bedroom

First-floor front bedroom before the works — Front bedroom

Family bathroom after the works — Family bathroom

Original bathroom before the works — Family bathroom

Design Approach

Reconfigured from the Ground Up

Behind the front wall, the house was reconfigured almost entirely. The layout of two separate flats was taken out and the plan redrawn as one family home, which called for substantial structural work throughout.

To achieve generous head heights on every floor, we lowered the ground floor level and raised the ridge of the roof for the new loft. The house now feels taller and lighter than its Victorian footprint suggests.

At the front, the house was given back its Victorian character. The bay was restored, new white sash windows were fitted, the path was relaid in black and white geometric tiles and the boundary wall was rebuilt in yellow stock brick with black railings and a matching gate.

A Rear Wraparound Extension for Family Living

The ground floor now runs from front to back as a sequence of rooms. The bay-fronted main reception room sits at the front, followed by a dining room, then the kitchen and a second, informal living area inside the rear wraparound extension. A WC is tucked beneath the stairs.

The wraparound extension fills the side return and pushes into the garden, turning a narrow, dark rear into one wide, open room. Large rooflights bring daylight deep into the plan, and black framed bifold doors open the kitchen onto the small courtyard garden, which was retiled as part of the works. A single step marks the change in level between the original house and the extension.

A Generous First Floor

The first floor now holds a master bedroom with its own ensuite, a spacious bedroom at the rear and a large family bathroom. The bathroom is finished in fluted marble-effect tiles, with a freestanding bath, a walk-in shower and brushed brass fittings.

An L-Shaped Mansard Loft with a Raised Ridge

At roof level, an L-shaped loft dormer extension wraps over the main roof and the rear outrigger. Its faces are sloped in mansard style so that it sits comfortably among the neighbouring roofs, and the raised ridge gives full head height across the new floor.

The loft holds a child’s bedroom or study and a second master suite with its own ensuite, both lit by rooflights. French doors open onto a Juliet balcony with black metal railings, with long views across the gardens and rooftops of Kensal Rise.