Yes, for most homes in Theale, and the post-war streets are the easiest. Only a few dozen buildings are listed. Most of them line the old main road. The bigger constraint is the ground under the house, not the planning office. For a buyer planning a kitchen extension, Theale causes fewer problems than its history suggests.
Historic England lists 28 buildings in and around Theale. One is Grade I, none is Grade II*, and the other 27 are Grade II. Listing covers the whole building, inside and out, so replacement windows, a new staircase or a knocked-through wall all need listed building consent. Carrying out works without it is a criminal offence, and saying you didn't know is no defence. Most of these buildings are along the High Street, where the Georgian and Victorian frontages survive. The High Street itself is described as a conservation area, so anyone buying there should check the designation with the council before sketching a rear extension.
There is one scheduled monument in the area. That is the strictest level of protection, and it only matters if your land sits beside it.
The neighbours clearly extend. From April 2024 to June 2026 there were 1,437 planning applications in the Theale area, 632 of them in the last twelve months. That is a place busy with loft conversions, side returns and rear extensions. It doesn't tell you how many were approved, and nobody should assume yours will go through because your neighbour's did. It does show that people here extend their homes all the time.
Every postcode in Theale sits in class 3 for shrink-swell on the geological survey's hazard scale. Shrink-swell ground swells when wet and shrinks when dry, and it moves foundations when it does. It is not a reason to walk away. It does mean an extension here needs foundations designed for the ground, possibly deeper than a builder would dig by default, and a structural engineer's view before the quote is agreed. Trees near the footprint are worth mentioning to that engineer. A builder who says the ground is fine without having dug a trial hole is guessing.
Most of Theale's post-war semis and terraces sit outside the listed stock. For those homes, many modest single-storey rear extensions and loft conversions can proceed under permitted development, the national rules that allow some work without a full application. Anything larger, or anything on a listed building or in a conservation area, goes through the council. Check the specific property with West Berkshire Council before you exchange, not after the architect has sent the invoice.
Theale gives a homeowner a good deal of freedom to extend. Heritage rules only bite on the old High Street, and for everywhere else the real question is the foundations rather than permission.