Mostly yes, with conditions that depend on where the house sits. Around 95 buildings in the wider parish area are listed, three at the highest grade and two at the next tier. Five conservation areas cover sections of the village and its neighbours. The dominant building stock is post-war and outside both categories, so most houses can be extended under standard planning rules. The exceptions are the period stock near St Mary's Church at the heart of Old Barnham, and the houses inside the conservation lanes of the surrounding parishes.
The listing picture is what you would expect for a parish with churches at its heart. Of the 95 listed buildings within the wider boundary, three sit at the highest grade, two at the second tier, and the remaining 90 at the third. Most of the named entries are churches, ruins, and former manor or priory buildings, including St Mary's Church, Barnham Court, the monastic ruins of Boxgrove Priory, and the parish churches of the neighbouring villages dedicated to St Andrew, St George, St Margaret, and St Mary Magdalene. Listing means consent is required before changes to anything that affects the building's character: structure, windows, door surrounds, chimneys, internal layout in many cases, and often the boundary walls and outbuildings within the curtilage. For most owners that is a one-time aggravation at the start of a project rather than an ongoing problem, but it does mean any work needs an architect comfortable with the local conservation officer's preferences and a budget that allows for the longer route through approval.
Five conservation areas sit within the village's wider boundary. The named ones are Barnham (Church Lane), Eastergate Church Lane and Square, Norton, Walberton Village and Walberton Green, and Yapton Main Road and Church Lane. A conservation area does not lock the house down the way a listing does, but it tightens what owners can do without applying for planning permission. Replacement windows, satellite dishes, painted brickwork, dropped kerbs, and side extensions that would be allowed elsewhere by default can need planning permission inside a conservation area boundary. The exact picture varies by area and by the council's own designations within each, which is one of the questions to put to a planning consultant before exchange rather than after.
In practice, what this means for most Barnham buyers is straightforward. The majority of village homes sit outside both listings and conservation areas. The dominant stock is post-war detached, semi, terrace, and bungalow, none of which carry heritage constraints. A rear extension, a loft conversion, a side return, or a small dropped kerb for off-street parking will mostly be straightforward under standard rules, subject to size limits and the usual neighbour considerations. The story changes the closer the house sits to one of the conservation lanes or to a listed neighbour. Period cottages near St Mary's Church, properties on the central conservation lanes, and any building inside the wider curtilage of a listed entry will need the slower route through the planning office.
The verdict is moderate. Most of the village stock can be extended under standard rules, with the conservation pockets and listed buildings carrying the extra consent layer that comes with their age. Plan around the heritage, do not fight it.