House extensions & alterations

Two storey and first floor extensions

Extra bedrooms and bathrooms over new or existing ground floor space, designed to sit comfortably with the house and its neighbours.

Get a free quoteFrom £600 for homeowners

Why two storey extensions always need careful design

Two storey and first floor extensions almost always need a householder planning application, and they are judged more closely than single storey work because they affect neighbours' daylight, outlook and privacy and are visible from the street. Councils across Berkshire expect side extensions to be set back from the front wall and set down from the main ridge, to keep a gap to the boundary at first floor level, and to avoid a terracing effect where houses are close together. Rear extensions are tested against the 45 degree line from the nearest neighbouring window.

Our approach

We start with the constraints: the plot width, the position of neighbouring windows, the roof form and any trees. We then draw options, often two or three, so the client can see the trade offs between floor area and planning risk before one is chosen. Brickwork, render, tiles and window proportions are matched to the house, and side facing windows are obscure glazed where privacy matters. For more complex schemes we add 3D visuals so the client and the case officer can see the finished house.

What we have delivered

The projects below include a two storey side extension in Longworth refined to meet a 25 degree daylight line, a first floor front extension to a lodge within the curtilage of a listed building in Binfield, and two storey extensions to a care home in Sandhurst. Each one was drawn and submitted by us, with the supporting statements prepared in house.

Planning constraints we check

Two storey and first floor extensions are judged closely on their bulk and their effect on neighbours, so the local plan, the council's design guide and the daylight tests shape the design from the first sketch.

Local Plan policies: Reading Borough Local Plan 2019 (CC7 design, CC8 amenity, H9 house extensions, H11 garden land); Wokingham Core Strategy CP3 and the Managing Development Delivery Local Plan (TB06 garden land); the Bracknell Forest Local Plan; West Berkshire Local Plan Review 2023 to 2041 (SP7 design quality); Spelthorne Core Strategy and Policies DPD 2009 (EN1); Slough Core Strategy and saved Local Plan policies; and the National Planning Policy Framework.
Design guidance: The Wokingham Borough Design Guide SPD, Reading's Residential Conversions SPD and design guidance, the Slough Residential Extensions Guidelines SPD and the Bracknell Forest Design SPD, which set rules on scale, roof form, materials, set backs and separation distances.
Neighbour amenity: Daylight and outlook tested with the 45 and 25 degree methods in BRE 209 (Site layout planning for daylight and sunlight), overlooking distances, overshadowing and the effect of new windows on neighbours' privacy.
Heritage: Listed buildings and conservation areas under the Planning (Listed Buildings and Conservation Areas) Act 1990 and NPPF chapter 16, with heritage statements where needed.
Trees: Tree Preservation Orders and conservation area trees, root protection areas, and tree surveys, arboricultural impact assessments and protection plans to BS5837:2012 where building works come close to trees.
Ecology and biodiversity: Bat and nesting bird checks under the Conservation of Habitats and Species Regulations 2017, preliminary roost assessments where roofs or old buildings are affected, and Biodiversity Net Gain under the Environment Act 2021 with the statutory biodiversity metric (householder applications are exempt).
Flood risk and drainage: The Environment Agency flood map (Flood Zones 1 to 3), site specific flood risk assessments, the sequential test for new homes in higher risk zones, and sustainable drainage (SuDS) for surface water.
Highways and parking: The council's parking standards, access and visibility splays, Manual for Streets, refuse and delivery vehicle access, cycle storage and, for larger schemes, transport statements.
Green Belt, landscape and the Thames Basin Heaths: Green Belt tests on proportionate extensions and replacement buildings, National Landscape settings, and Thames Basin Heaths SPA mitigation (SANG and SAMM contributions) for new homes within 5km.
Community Infrastructure Levy: CIL liability under the Community Infrastructure Levy Regulations 2010 for new homes and extensions over 100 square metres, with self build and residential extension exemptions claimed before work starts.

Prices from£600 fee for the full package of documentation for our homeowner planning service

Fixed fee agreed before we start. Council application fees are paid separately. New dwellings, conversions, appeals and consultancy are quoted per project.

Questions

Can a two storey extension be permitted development?

Only in limited cases. A two storey rear extension can be permitted development if it is no deeper than 3 metres and at least 7 metres from the rear boundary, with matching materials and no side windows that overlook. Two storey side extensions always need planning permission.

Will my neighbour's daylight stop the extension?

Not usually, if it is designed properly. We check the 45 degree and 25 degree daylight tests at the start, and shape the depth and roof of the extension so it passes.

10 projects