Building and Extending in Test Valley

Test Valley is a Borough of considerable variety — from the market towns of Andover and Romsey to the chalk stream villages of the Test and Anton valleys, and the quieter countryside that sits between them. It is also a planning area with its own specific designations and policies that bear directly on what is possible, whether you are extending an existing home or building a new one. Understanding them early makes the process considerably more straightforward.

This guide covers both: the planning rules that apply to extensions and alterations, and the routes available to clients who want to build a new home within the Borough.

New build homes in Test Valley

The Test Valley Adopted Local Plan (2011–2029) takes a settlement-led approach to new residential development. This means that the principle of new housing is generally supported within the boundaries of the Borough's defined settlements — Andover, Romsey, and the network of villages identified in the settlement hierarchy — but is significantly more restricted in the open countryside between them.

Within settlement boundaries, a new home is supportable in principle, subject to design quality, compliance with local plan policy, and the character of the immediate setting. The Local Plan identifies a hierarchy of settlements — from the main urban areas down through market towns, local service centres, and rural villages — and the level of new development considered appropriate broadly reflects where each settlement sits in that hierarchy. A plot within the settlement boundary of Stockbridge or Kings Somborne will be assessed differently from one in a smaller hamlet with no defined boundary.

Outside settlement boundaries, in the open countryside, new residential development is not permitted as a matter of course. The same national framework that protects rural Hampshire more broadly applies here — the NPPF's strong presumption against new housing in the countryside, combined with Test Valley's own local plan policies for rural areas. There are, however, three established routes available.

The first is a replacement dwelling — where an existing home is demolished and replaced with a new one. Test Valley's local plan permits replacement dwellings in the countryside where the new home is not materially larger than the one it replaces, is not overbearing in the landscape, and does not introduce a built form or material character that would be out of keeping with its rural setting. The principle of residential use is already established, which lowers the planning risk considerably compared to a genuinely new dwelling.

The second is rural workers' housing — where there is a demonstrated operational need for an agricultural, horticultural, or forestry worker to live at or immediately adjacent to their place of work. The evidential bar is high: the business must be established and financially viable, the functional need for on-site accommodation must be convincingly argued, and the dwelling will typically be subject to an agricultural occupancy condition that ties it to the rural enterprise in perpetuity.

The third is a Paragraph 80 application under the NPPF — an isolated dwelling in the countryside of truly exceptional architectural quality. This route is demanding in its evidential requirements and involves a design review process that adds considerably to the programme. It is not suitable for every site or every client, but for the right project in the right location it offers a genuine route to building a home of real distinction in the Test Valley countryside.

What Test Valley looks for in new build design reflects the character of the Borough's landscape and settlement pattern. The chalk geology defines the traditional palette — red and warm-brown brick, flint with brick detailing, clay plain tile and natural slate, limewash and render — and new buildings are expected to demonstrate an honest engagement with these materials rather than imposing a character from elsewhere. Contemporary design is accepted where the quality is demonstrable and the design argument is coherent. The approach that works best in Test Valley is one that takes the landscape and the vernacular seriously, finds the contemporary expression that belongs in that place, and makes that argument clearly in the application.

Extending an existing home

Do you need planning permission?

The starting point for any extension project is understanding whether planning permission is required at all. Permitted Development (PD) rights allow homeowners to extend without a full planning application, within nationally set limits on size, height, and position. Under current rules, permitted development typically allows single and double-storey rear extensions, side extensions, and loft conversions, subject to specific dimensional thresholds.

However, a significant proportion of Test Valley properties sit in areas where permitted development rights are reduced or removed entirely, and assuming your project falls within PD without checking is one of the more common and costly mistakes clients make.

Conservation areas

Test Valley has 36 Conservation Areas, covering parts of Andover and Romsey as well as a number of villages including Stockbridge, Abbotts Ann, Longparish, Chilbolton, and the Wallops. Within them, works that would be permitted development elsewhere frequently require full planning permission. External cladding, side-facing windows visible from a public road, alterations to front-facing rooflights, and changes to window or door materials affecting the character of the property all require consent in a conservation area. Where an Article 4 Direction has also been applied — removing permitted development rights further — virtually any external alteration triggers a planning requirement.

Before any design work begins, the first step is to check whether your property sits within a Conservation Area boundary. Test Valley Borough Council maintains Conservation Area Appraisals for each designation — documents that set out the character, significance, and design priorities for that area. These are directly relevant to how a planning application will be assessed and should inform the design from the outset.

Residential Areas of Special Character

Test Valley has a designation called Residential Areas of Special Character (RASC), protected under Policy E4 of the Adopted Local Plan. These are specific neighbourhoods — primarily in Andover, Romsey, and Chilworth — defined by low-density housing, generous plots, and mature planting. The Council actively protects this character from being eroded by overdevelopment, and the primary test applied is whether an extension would overwhelm the relationship between the dwelling and its garden.

In practice, this means that a large footprint addition — even one that is well-designed in its own right — can be refused in a RASC if it reduces the openness of the site to a degree that changes its essential character. Wraparound extensions deserve particular attention here: they are popular because they reorganise ground-floor living effectively, but in a RASC or Conservation Area they require careful handling of massing and composition. A design that reads as two subordinate additions rather than one dominant intervention tends to fare considerably better.

Policy COM11 and Policy E1

When full planning permission is required, two policies from the Test Valley Adopted Local Plan are most directly relevant. Policy COM11 covers extensions to dwellings in the countryside; Policy E1 sets the design quality standard across the Borough. Both share a central principle: the extension must be proportionate and subordinate to the original building. The detailed design tests that flow from this include the relationship of scale and massing, the appropriateness of the roof form, the consistency of the material palette, the proportions of windows and openings, and the impact on neighbouring properties in terms of daylight, outlook, and privacy.

Officers will assess these things on a case-by-case basis, and the quality of the design argument matters. A well-prepared planning application — with a clear design and access statement, accurate drawings, and a response to the specific constraints of the site and its context — puts the LPA in a position to support the proposal. A poorly prepared one invites conditions, amendments, and delays.

Materials

The Test Valley vernacular is specific, and it is worth understanding before making design decisions. The traditional material palette of the area reflects the chalk geology and river landscape that define it: red and warm-brown hand-made facing brick, flint used in panels with brick quoins and lacing, natural clay plain tile or natural slate for roofing, and occasionally wheat-reed thatch in the more rural village settings.

This does not mean that every extension or new build must replicate a historic building. Contemporary approaches — dark-stained timber, standing seam zinc, carefully detailed black steel — can be accepted in Test Valley where the design argument for their use is clearly and convincingly made. What tends not to work is material selection that sits in an uncertain middle ground: bricks in yellow, grey, or pink tones are explicitly identified as non-native to the region; concrete roof tiles are routinely flagged as a suburbanising influence in rural and village contexts. The cleaner the material logic, the stronger the application.

What does it cost?

Build costs across Hampshire have remained elevated since 2022. As a general guide for 2026:

Extensions: A good quality standard finish sits at approximately £2,800 to £3,400 per square metre. A high specification finish with considered detailing and premium materials sits at £3,500 to £4,200 per square metre. A project with fine joinery, structural glazing, stone finishes, and complex roof forms will typically run at £4,500 per square metre and above.

New builds: One-off architect-designed homes in Test Valley are typically delivered at £3,200 to £4,000 per square metre for a well-specified build, rising to £4,500 to £5,500 per square metre and above for ambitious contemporary homes with high-quality materials, bespoke joinery, and complex structural arrangements. External works, landscaping, and infrastructure connections are additional costs that are easy to underestimate at the outset and worth budgeting for early.

Professional fees — architect, structural engineer, and where required, a planning consultant or heritage specialist — typically add 12 to 15% of the build cost. Projects in Conservation Areas or RASCs, or new builds in sensitive rural locations requiring pre-application discussions, sit toward the upper end of that range.

The planning fee for a standard householder application is currently £548. A full planning application for a new dwelling is calculated on a per-dwelling basis at £610. Building Regulations consent is required separately for all structural work.

The value of early planning advice

The projects that proceed most smoothly are those where the planning strategy is established before the design is fixed. For extensions, this means knowing whether your property sits in a Conservation Area or RASC before a design direction is committed to. For new builds, it means understanding the settlement boundary position of your site and the realistic planning route available before any significant design resource is invested.

We work with clients across Test Valley — Andover, Romsey, Stockbridge, and the surrounding villages — on extensions, renovations and new build projects, from initial feasibility through planning and into delivery on site. If you are thinking about what might be possible and want an honest early view, we would be glad to hear from you. Get in touch.