You can extend most houses in Windsor, but a few hundred of them need permission for almost any change. Over three hundred buildings are listed. Only one conservation area covers this patch. Neighbours file planning applications at a steady rate. The ground is barely a factor. Ordinary houses here are straightforward to extend, and listed ones are much harder.
Historic England lists 320 buildings in the area. Three are Grade I, 25 are Grade II* and 292 are Grade II. Listing covers the whole building, inside and out, so on a listed house you need listed building consent for new windows, a removed wall, a moved fireplace or a rear extension, and the council judges the effect on the historic fabric. Working without consent on a listed building is a criminal offence. In the poorer centuries, Windsor owners put fashionable new fronts on decaying houses. Doing that now would need listed building consent, and it would be refused.
One conservation area is in the immediate area, Boveney. Inside a conservation area, changes that would be permitted elsewhere can need planning permission, and demolition, some roof alterations and work to trees all face extra checks. Outside Boveney, the conservation-area rules don't apply here, though they won't help much if your house is listed.
There are two scheduled monuments in the area. Scheduling is the strictest protection there is, and it mainly matters if your land is next to one.
People do alter their homes here, and in large numbers. The Royal Borough of Windsor and Maidenhead logged 2,003 planning applications for the area between April 2024 and June 2026, 858 of them in the last 12 months. That count shows how often people apply. It doesn't show how many were approved. Windsor tried a major modernisation of its medieval centre in the 1680s and gave up because the town couldn't afford it, so the town has a long record of changing its buildings slowly.
The British Geological Survey's shrink-swell rating, for clay ground that swells when wet and shrinks when dry, reaches class 3 in Windsor at its highest. That class covers well under 1% of the area. For almost every extension, ground movement won't be a problem. A structural engineer should still confirm the foundation depth, especially near large trees.
One listed building in the area is on Historic England's Heritage at Risk register. That means it is in poor condition, and its repair may qualify for grant support and will be closely checked. It doesn't affect ordinary houses nearby.
In practice, an unlisted house outside Boveney can usually rely on permitted development for a modest rear extension or a loft conversion, within the national size limits. Anything bigger, or anything on a listed building, needs consent from the Royal Borough. Particulars that mention "period features" are describing the parts of the house you'll need permission to change. Before you offer, check whether the house is listed and whether it's in Boveney, and if you're unsure whether a project needs permission, ask the council for a lawful development certificate.
Overall, your freedom to extend in Windsor is limited. Unlisted houses are fairly easy. On the 320 listed buildings, you'll need consent for most of what you want to do, and you may not get it.