St Agnes is a large village on the north Cornish coast between Perranporth and Porthtowan, about eight miles from Truro. Its history as a mining centre is still visible everywhere, from the engine houses at Wheal Coates and Chapel Porth to the old miners' cottages that line the steep streets down to Trevaunance Cove. That history, together with the dramatic coastline and St Agnes Beacon, shapes how building work needs to be planned.
This guide covers what to think about before starting building work in St Agnes and nearby villages such as Mithian, Mount Hawke and Porthtowan. It is general guidance only, so always check the position for your own property with Cornwall Council.
Planning considerations in St Agnes
Several designations can apply to homes in and around the village:
Conservation area: the historic core of St Agnes is a designated conservation area. Permitted development rights are reduced, and changes such as cladding, render, roof alterations, replacement windows and work to boundary walls can need planning permission.
Cornwall National Landscape: the coast and Beacon around St Agnes fall within the Cornwall National Landscape (formerly the Cornwall AONB), where the size, materials and visibility of new work are looked at closely.
World Heritage Site: the St Agnes mining district is part of the Cornwall and West Devon Mining Landscape World Heritage Site. Proposals within it are assessed for their effect on the historic mining landscape.
Listed buildings: engine houses, chapels and a number of older homes are listed, and almost any alteration to a listed building may need listed building consent.
Neighbourhood plan: St Agnes parish has its own neighbourhood development plan, used alongside the Cornwall Local Plan when applications are decided. Read its policies, including any on housing and design, before you plan anything.
Our guide to building in an AONB or conservation area explains what these designations mean in practice, and our listed building renovation guide covers consent.
Old mine workings and ground conditions
The ground around St Agnes has been mined for centuries, and old shafts, adits and shallow workings are found across the parish, sometimes in gardens or under existing buildings. Before buying a property, extending it or building something new, a mining search is strongly advisable, and further ground investigation may be recommended if the search or the site suggests a risk. Foundations may need to be designed with this in mind.
Some houses in the area built between the 1900s and 1950s may also contain mundic concrete, made with mine waste aggregate. Mortgage lenders often ask for a mundic test on concrete-block homes of this age. Our guides to building on old mining land and mundic block homes explain what to check, and our groundworks and foundations service covers the work itself.
Cornwall also has higher natural radon levels than most of the UK, so new homes and extensions may need radon protection. See our guide to radon protection.
The kinds of homes you find in St Agnes
Housing in the parish broadly falls into a few groups:
Miners' cottages and terraces: stone or rendered homes with solid walls, slate roofs and small rooms, many on steep streets with little outside space.
Victorian and Edwardian villas: larger houses built as the village grew, often with bay windows and decorative details.
Later housing and bungalows: twentieth-century homes on the edges of the village and in Mount Hawke and Goonbell, which often have more room to extend.
Coastal homes and holiday lets: properties near Trevaunance Cove and Porthtowan that face the full Atlantic weather.
Older solid-wall homes generally need breathable materials and careful detailing. Our guides to damp in Cornish homes, insulating solid-wall stone houses and renovating an old Cornish cottage explain why.
Steep streets, access and coastal weather
Many roads in St Agnes are steep and narrow, particularly down towards Trevaunance Cove, and parking can be tight. Deliveries may need smaller vehicles, skips and scaffolding on the highway normally need a permit from Cornwall Council, and sloping gardens may need stepped foundations or retaining walls. Our guide to retaining walls and sloping sites covers this.
Close to the cliffs, salt spray and wind-driven rain are hard on render, roofs, windows and metal fixings. Our guide to weatherproofing coastal homes covers suitable materials.
Common building projects in St Agnes
The projects we are most often asked about in villages like St Agnes include:
Sympathetic renovations of miners' cottages, including repointing, re-rendering in lime and damp repairs. See our stone, rendering and lime work service.
Extensions and loft conversions on homes outside the historic core. See our home extension service and loft conversions guide.
Holiday let upgrades between seasons; see our holiday let renovation guide.
Garden offices and studios where a plot allows. See our garden offices service.
Older terraces often share walls with neighbours, so the Party Wall Act may apply; see our Party Wall Act guide. Old roofs and outbuildings can also be home to bats, so read our guide to bat surveys and building work.
Planning and Building Regulations
With several overlapping designations, it is sensible to check before designing any external change. Our guide to planning permission in Cornwall explains the process, and Cornwall Council offers pre-application advice for more complex schemes. Building Regulations approval is a separate requirement, and our Building Regulations guide explains how Building Control works.
Frequently asked questions
Is St Agnes in a World Heritage Site?
The St Agnes mining district is one of the areas that make up the Cornwall and West Devon Mining Landscape World Heritage Site. Check Cornwall Council's mapping for your address.
Do I need a mining search in St Agnes?
For buying, extending or building in the St Agnes area, a mining search is strongly advisable because of the area's long mining history. Your solicitor or a specialist can arrange one.
Do you cover St Agnes?
Yes. We work across the whole of Cornwall, including St Agnes, Mithian, Mount Hawke, Porthtowan and the villages between Truro and the north coast.
Planning building work in St Agnes? Talk to us
Cornish Building Company works throughout mid and north Cornwall. See our pages for builders in Truro and builders in Newquay, our guide to building work in Perranporth, our property renovation service, and the full list of areas we cover. Call us on 01208 816991 or contact us to talk through your project.
