Start with the shape of the building

Before you reach for the archives, stand back from the cottage and look at its overall form. The footprint of a building is often the single most revealing clue, because fashions in plan layout changed slowly but steadily over the centuries. A simple two-room cottage with a central chimney stack and a door in the middle is very different from a long, low range with a gable-end stack and an outshot at the rear.

Ask yourself what the building is trying to do. Is it symmetrical, with windows either side of a central door? That symmetry usually points to the late seventeenth century or later, when polite architecture began to influence even modest rural homes. Is it a rambling, uneven thing that seems to have grown a little at a time, each section at a slightly different angle? That organic quality often suggests a medieval or Tudor origin, with later additions bolted on as the family's fortunes or needs changed.

Walk around it twice. The front is often the most altered elevation, because that is where owners spent money and made an impression. The back, the gable ends and the roof are usually more honest.

Read the windows

Windows are among the most reliable dating tools in a stone cottage, partly because glass was expensive and fashion changed quickly. If the cottage retains any original openings, examine the stonework around them as carefully as the frames themselves.

• Mullioned windows with stone uprights between the lights are a strong indicator of the sixteenth or early seventeenth century. The mullions are usually chamfered, and the lights are tall and narrow.
• Small, square, leaded lights set into timber frames, often with a hood mould above, suggest the seventeenth century. Look for diamond or rectangular lead cames.
• Sash windows, especially with thin glazing bars and six panes over six, point to the Georgian period, roughly 1700 to 1830. The stone reveals around them are usually flat rather than chamfered.
• Plain, wide-paned sashes or simple casements with no glazing bars belong to the Victorian and Edwardian eras, or to later replacements.

Be cautious here. Windows are the first thing to be replaced, and a stone cottage may have had three or four sets over its lifetime. Look at the stone jambs rather than the timber. A straight, square reveal cut cleanly into the wall is likely original; a ragged opening patched with brick or cement is probably a later insertion.

Study the roof and its line

The roofline tells you how the cottage was built and how it has been altered. A steep pitch, often around 45 to 55 degrees, is typical of thatch, which needs a sharp angle to shed water. If a cottage was originally thatched and later re-roofed in slate or stone, the pitch may have been reduced, and the walls may have been raised with an extra course or two of stone to accommodate the new covering.

Look for the ghost of an earlier roof. A straight joint running up a gable end, or a band of different stonework just below the eaves, often marks a heightening. Chimney stacks are another giveaway. A massive stack built into the wall, especially one with a wide base and a clustered top, is usually older than a slender stack standing at the gable end. Multiple stacks on a small cottage suggest a later division of rooms, or a rebuilding of the hearth.

Also look at the eaves. A shallow overhang with exposed rafter ends, sometimes with decorative mouldings, is a good sign of a timber-framed or early stone building. Tight, flat eaves are usually later.

Examine the stonework itself

Stone is local by necessity. Before canals and railways made heavy materials cheap to move, cottages were built from whatever lay within a few miles, so identifying the stone can anchor you to a place and sometimes to a date.

• Irregular rubble with thick, wide mortar joints often indicates an early building, perhaps fifteenth to seventeenth century. The mortar was lime, soft and breathable, and it has usually weathered back.
• Coursed rubble, where stones are roughly sorted into horizontal bands, suggests the seventeenth or eighteenth century, when builders became a little more orderly.
• Squared and dressed stone, with neat ashlar blocks and thin joints, points to the eighteenth century or later, or to a house built for someone with money.
• Brick quoins at the corners, or brick patching around openings, often date from the eighteenth or nineteenth century, when brick became affordable.

Run your hand over the wall. Big, flattish, roughly shaped stones with a pronounced batter at the base are a strong hint of an early origin, sometimes medieval. Look out for putlog holes too: small square gaps left in the stonework where scaffolding poles once sat. They are usually original and can survive for centuries.

Look for the little things

Details are where the real pleasures lie, and they often outlast the grand gestures. A chamfered beam over a fireplace, a stopped run of moulding on a stone lintel, a small blocked opening that once lit a stair, or a bread oven bulging into an outside wall all speak to a working life. Tally marks, masons' marks and carved dates, though rare, are worth hunting for on quoins and lintels.

None of this replaces the written record, and you should treat every clue as a hypothesis rather than a fact. But a careful walk around the outside, a notebook and a torch will give you a sound framework. Take that framework to the archives, and the documents will have something solid to argue with.