Yes, in almost every case. The area carries 24 listed buildings. There are no conservation areas inside the town footprint. Three scheduled monuments sit on the edges. The post-war estates that make up most of the place are being extended one rear conservatory at a time, and nobody is stopping them.
The listed-building register for the area runs to 24 entries. Twenty-one sit at grade two, the standard level of statutory protection. Three are at grade two star, the higher tier that flags a building of more than special interest. None reach grade one, which is reserved for buildings of exceptional importance. Most of the listings cover churches, forts and a handful of named period buildings: the churches of St Faith, St Thomas-a-Becket, and St Peter and St Paul, the forts at Purbrook and Widley, and country-house listings including Wymering Manor, Warblington Castle, Rookwood, The Elms, and the Staunton Memorial. None of the listings sit on the post-war housing stock that fills most of Waterlooville's streets, because that stock is too young and too ordinary to qualify. If you own a listed building here, you already know it. The consent process is then a question of working with the council and the historic-environment authorities on every external change, every internal change above a minor threshold, and every set of windows.
In practice this is one of the freer corners of southern England for altering a home. The absence of any conservation area inside the town footprint is the headline fact, because conservation areas, more than listings, are what catches most owners elsewhere on the south coast. A typical front-door replacement, window upgrade, single-storey rear extension, loft conversion or render job goes ahead under permitted development rights, without an application to the council. The thresholds for needing full planning permission are the standard national ones: a side extension over a certain height, a front extension forward of the building line, anything that exceeds the permitted depth limits at the rear, or anything visible from a designated landscape, of which the town has none. The three scheduled monuments are archaeological sites at the edges, not buildings anyone lives in, and they constrain only their own footprints. The architecture of the town is therefore being shaped, slowly, by what permitted development allows, not by what the historic-environment authorities prevent.
Freedom to extend in Waterlooville is real, but unevenly distributed. Most homes can be added to under permitted development; a small number of listed buildings cannot be touched without consent. The town will not test your patience with planners often, but the few addresses where it does will test it thoroughly.