Begin With the Building, Not the Mood Board

Old coastal cottages are seductive. Thick walls, weathered stone, a view of the sea and a price tag that looks almost reasonable until you lift a corner of carpet. Before you choose paint colours or order a new kitchen, spend your first money on knowledge. Commission a full building survey rather than the cheapest mortgage valuation, and if you can, find a surveyor who knows period coastal stock — stone, cob, clunch, timber frame, brick with lime render. Each behaves differently, and generic advice often does more harm than good.

Ask the surveyor to look specifically at the things that go wrong by the sea:

• Roof structure, fixings and the condition of chimney stacks, which take the brunt of the wind.
• Embedded timber — lintels, wall plates and beam ends — where rot hides behind plaster.
• External ground levels, drainage runs and gullies, since water pooling against a wall is the most common cause of damp.
• Long-term coastal change. Check flood risk and shoreline management information held by your local authority before you commit, not after.

Confirm too whether the cottage is listed or sits in a conservation area. That single fact determines what you can change, how long it will take, and whether you need listed building consent before a single window is touched.

Damp Comes First — Always

Nothing else you do will hold if the building is wet. Coastal cottages face wind-driven rain, salt-laden air and high humidity, and they usually have several small leaks rather than one dramatic one. Work through the obvious culprits before you consider anything invasive: blocked or undersized gutters, cracked downpipes, failed mortar joints, leaking chimney flashings, and ground levels that have crept up over the decades to sit above the internal floor.

Be sceptical of the quick fix. Injecting a chemical damp-proof course into a solid stone or cob wall rarely solves the problem and can trap moisture where you least want it. Traditional walls are designed to breathe: they absorb water and release it. Cement render, plastic paint and gypsum plaster all seal the surface and push damp inward. Repairs should use lime mortar, lime plaster and breathable paints so the wall can dry in the same direction it always has.

Salt is the coastal complication. Salt drawn into the wall from sea spray and ground water sits in the plaster and pulls moisture out of the air, so a wall can feel damp even when there is no leak. This is usually treated with repeated poulticing to draw the salt out, or by removing contaminated plaster and replacing it with a sacrificial lime mix that can be renewed later.

Insulate and Heat With Care

Once the building is dry, insulation is the highest-value improvement you can make — but it must not trap moisture. On solid walls, avoid impermeable boards fixed directly to the inside face. Breathable options such as wood fibre, hemp-lime, cork and sheep's wool work with the wall rather than against it, though they are thicker, so you lose some floor area.

Lofts are the easiest win; aim for at least 270mm of insulation and keep the eaves ventilation clear. Suspended timber floors can be insulated from below, but never block the air bricks — cross-ventilation under the floor is what keeps the joists dry. Draught-proofing gives a surprising amount of comfort for very little money, and secondary glazing is usually the sensible route for original sash or casement windows, keeping the character and the planning officer happy.

If you are considering a heat pump, plan for it early. It will want a well-insulated envelope and larger radiators or underfloor heating, and the pipework is far cheaper to run before the floors and walls are finished. Equally, do not seal a cottage airtight. Old buildings need controlled ventilation — trickle vents, extract fans or a mechanical system with heat recovery — to keep humidity down and condensation at bay.

Protecting the Fabric From the Weather

The exterior takes a beating, so treat it as a system rather than a set of separate jobs. On the roof, check that slates or tiles are correctly fixed against wind uplift, that fixings are corrosion-resistant, and that mortar is lime-based rather than brittle cement. Fit oversized gutters and downpipes where you can, keep them clear, and check them after every winter storm.

On the walls, retain lime render and repoint with lime mortar matched to the original. Keep external ground levels at least 150mm below the internal floor, and make sure paving falls away from the building. French drains and soakaways help in heavy rain, but only if they discharge somewhere sensible. Plant salt-tolerant hedging as a windbreak rather than a solid fence, which simply shifts the pressure elsewhere.

Permissions, Order of Work and Budget

Listed building consent, conservation area rules and Article 4 directions can all remove the permitted development rights you assumed you had. Speak to the conservation officer early — they are usually far more helpful at the start of a project than at the end. In flood-risk areas, consider resilience measures: raised sockets, hard floors, breathable wall finishes and a sensible place to move valuables.

Sequence the work properly: survey, strip out and make watertight, structural repairs, rainwater and drainage, insulation, first-fix services, plaster, second fix, decoration, then external landscaping. Give yourself a 20–25% contingency — coastal properties always hide something — and if possible, live through one winter before finalising the decorative choices. The sea will tell you what the building needs.