Yes, and with unusually little standing in the way. No conservation area covers the town. Nothing in the area is listed at the top grade. The old buildings that do carry protection sit out in the surrounding villages, quietly getting on with being old. Extending a house here is a negotiation about your neighbour's light and your own budget, not about a planning officer's feelings towards a doorway.
Across the area there are 40 listed buildings: none at grade one, two at grade two star and 38 at grade two. Listing is the constraint that actually bites, because it applies to the whole building rather than the bit facing the street, and it catches internal work as readily as a rear extension. Anyone buying one of those 40 is in a different world from anyone buying a house built this century, and the difference shows up in consent timescales, in materials, and in the number of people who get an opinion. For everyone else in the town, that list is a curiosity rather than a constraint.
Volume is the better evidence than policy, and there is plenty of it. The planning record for this area carries 1,070 applications between April 2024 and June 2026, with 458 of those in the last twelve months. People here are extending, converting, glazing and reconfiguring at a steady clip, which is what happens when a town fills up with families who bought the house that fitted and then had another child. Outcomes are a separate question and the record does not support any claim about them, so treat the number as proof of appetite rather than proof of success.
In practice, the split is the usual one. A modest rear extension, a loft conversion or a garden room on a house often falls under permitted development and needs a lawful development certificate rather than a full application. Anything larger, anything to the front, and anything on a flat needs a proper application. The particular trap on new estates is the original consent: conditions attached when the site was approved can strip out permitted development rights that would apply anywhere else, and covenants in the title can add another layer on top. Both are worth reading before the architect is, because neither turns up in the estate agent's description.
Freedom to alter your home is genuinely one of Cranbrook's strengths. The heritage protection sits elsewhere, the planning department is dealing with a busy modern town rather than a museum, and the main thing standing between you and a bigger kitchen is the paperwork attached to your own deeds.